https://doi.org/10.1177/1071100720950715

Foot & Ankle International® 1 –3© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950715journals.sagepub.com/home/fai

Letter to the Editor

Adult-acquired flatfoot deformity (AAFD) represents a pathology in orthopedic foot and ankle surgery that we all commonly see, yet in many different forms. Our experience has grown over the years thanks to the research and clinical experience and great insights of authors from all over the world. However, with the onset of new surgical techniques, technology, and imaging modalities, the understanding of the details of this complex pathology has grown exponen-tially. Despite these advances, it is often confusing not only when to decide to operate but also which procedures to per-form, how much correction to achieve, and even what to call the condition itself.

With that background in mind, we embarked upon a project starting at the beginning of 2019 to bring together a group of experts to help collectively answer some of the doubts we have and potentially resolve some of the differ-ences in opinion many have about treating AAFD. The rationale to bring a group together was to share and build from a collective larger number of years of experience from experts around the country and world. We all have our ideas about the physical exam, imaging, and treatment. The liter-ature also lacks a more formal and uniform agreement on terminology and clinical and surgical algorithms. In addi-tion, literature reviews are limited by the nature of their study design, and it can take years to advance the field in this fashion. We therefore sought to guide ourselves and colleagues in a more immediate fashion. We also followed the precedent set by our colleagues to form consensus group statements in the area of ankle cartilage injuries and muscu-loskeletal infection.1,2

With this in mind, 2 of us (C.C.N., S.J.E.) performed a literature search to identify experts in the field of AAFD. In the spring of 2019, we performed this search via PubMed and selected a group of 9 experts in the field who had a minimum of 10 peer-reviewed publications in impactful journals reporting on various aspects of the assessment and treatment of AAFD. Not surprisingly, these individuals are well known in the field and have taught us through their publications and presentations at meetings, and all have at one point been faculty at orthopedic foot and ankle fellow-ship programs. We chose the specific number of individuals (9) to provide a wide array of thoughts from thinkers from different parts of the country and world with varied training backgrounds. We chose an odd number of members to break potential ties when the time for consensus voting began.

The group met in person on November 2, 2019, at the Hospital for Special Surgery (HSS) in New York, New York. The location was chosen given the relative ease of travel for members coming from across the country and world. All travel and hotel costs were paid individually by the participants. Each member was asked to give a talk in his relative area of expertise within AAFD, based largely upon previously published translational and clinical research. Each talk was 10 minutes long, followed by a dis-cussion of approximately 1 hour. The meeting was recorded by audio in its entirely, and research assistants took written notes throughout. For each talk, we generated a small series of consensus statements that could help us synthesize useful guidelines and summarize current thinking in the field. The topic of gastrocnemius/Achilles tightness, although cer-tainly important in the pathophysiology of the collapsing flatfoot, was not chosen given its controversial nature, the difficultly to reach consensus, and the lack of data to sup-port consensus statement rationale. Two weeks after the meeting, the consensuses statements were sent out to all 9 members for voting. The vote for each statement consisted of agree or disagree. The strength of each consensus state-ment voted was based on the percentage of approval: unani-mous (100%), strong (higher than 75%), and weak (in between 50% and 75%). Once the final statements were selected, each member was asked to write a summary man-uscript with the rationale to support the statements related to his talk based on the previous group discussion, clinical experience, and literature support. Each manuscript was then sent out to all other members of the group for com-ments and editing. Once finalized, the body of work was submitted to Foot & Ankle International for peer review.

We hope that you learn as much as we did from reading these manuscripts, statements, and rationales. There are many questions that are still left unanswered. We attempted to point out clearly where there is agreement and were future work is needed to come to consensus. We believe that this is an important first start. Perhaps as important as anything, we propose a new terminology and classification that is simple yet clinically meaningful. We recommend calling this condition progressive collapsing foot defor-mity (PCFD). Throughout the manuscript, when conven-tional radiographs are mentioned, we decided to capitalize and underline the word WEIGHTBEARING to repeatedly emphasize the importance of obtaining weightbearing

950715 FAIXXX10.1177/1071100720950715Foot & Ankle Internationalde Cesar Netto et aleditorial2020

Editorial: Expert Consensus on Adult-Acquired Flatfoot Deformity

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imaging when evaluating patients. We also are including a glossary of controversial terminology to help better define and bring uniformity to some of the definitions that we use. We found that different words can be used to describe the same concept and that have regional and historical bases. It was difficult to come to consensus with some of this termi-nology also given the precedent in the literature.

We hope you are all safe during difficult times of COVID-19 crisis.

Take care!

Glossary: Nomenclature Describing PCFD

As noted above, the consensus group advocated for the use of the term progressive collapsing flatfoot deformity (PCFD) instead of adult-acquired flatfoot deformity (AAFD) for various reasons. Taking the word adult out allows us to include younger patients without a history of congenital foot disorder or coalition in the treatment algo-rithm for this pathology. The term progressive describes the natural history of the disorder. We have favored col-lapsing over flatfoot since many patients with a flat arch do not have pathology or pain. The use of foot deformity denotes that this is not just routine foot care but rather a true pathology that will help combat insurance denials that claim that “flatfoot” is routine foot care. It is only when the “arch” progresses on to collapse that it becomes a problem. We have used this terminology throughout the rationale statements.

Abduction

Abduction describes the position of the forefoot as being in a laterally deviated position with respect to the hindfoot. Typically, the forefoot is laterally deviated due to the navic-ular rotating in eversion around the curved surface of the talar head. Abduction deformity can also occur in the mid-foot or forefoot joints (through the naviculocuneiform or tarsometatarsal joints) due to ligament instability or osteo-arthritis causing lateral deviation of the midtarsal or meta-tarsal bones.

Foot Pronation and Supination

Pronation and supination are terms used to describe the weightbearing posture of the foot in its normal base of standing with both feet on the ground. These terms can also be used to describe the direction of motion, as during the midstance phase of gait when the fully loaded foot dynami-cally “pronates” to allow the dissipation of weightbearing forces of walking and the same foot then “supinates”

during late-stance phase to lock the transverse tarsal joint to provide a stable midfoot during toe-off phase of gait.

Pronation of the foot is characterized by deviation of the foot in 3 planes of motion, including subtalar joint eversion (hindfoot valgus), ankle joint plantarflexion (talus is plan-tarflexed), and forefoot abduction (lateral deviation of navicular around the curved talar head), allowing the medial arch of the foot to be closer to the floor.

Supination of the foot is characterized by deviation of the foot in 3 planes of motion, including subtalar joint inversion (hindfoot varus), ankle joint dorsiflexion (talus is dorsi-flexed), and forefoot adduction (medial deviation of the navicular around the curved talar head), allowing the medial arch of the foot to be raised away from the floor. The term supination will describe the static position of the “cavus foot” in weightbearing stance. It can also be used to describe the dynamic “supination” motion that occurs in the normal foot during late-stance phase of gait when inversion of the foot stabilizes the transverse tarsal joint during heel rise.

Forefoot Varus (aka Forefoot Supination)

Forefoot varus is not to be confused with the term supination, which applies to the entire foot. Varus of the forefoot is exam-ined with the hindfoot held in a neutral “reference” position relative to the tibia and then the forefoot is viewed as being rotated in the coronal plane around the central axis of the foot toward the midline (or varus) direction. The first ray is visu-alized as being elevated above the fifth metatarsal (in the coronal plane) and can be characterized as only the first ray being elevated with the lesser rays plantigrade, or the entire forefoot may be rotated into varus (ie, global forefoot varus).

Forefoot varus may be further characterized by the degree of flexibility of the deformity when the examiner pushes cephalad on the plantar aspect of the fifth metatarsal head while holding the hindfoot in the neutral “reference” position. If the forefoot varus is correctible with this maneu-ver, it is termed flexible forefoot varus. If it does not correct, the deformity is determined to have some component of fixed deformity. In the literature, depending the publication and author, the words forefoot supination and forefoot varus may be used to express the same concept.

Hindfoot Valgus

Valgus refers to the lateral deviation of the hindfoot away from the midline of the body when viewing the heels of a patient from behind, either clinically or radiographically. Radiographically, the distance of the weightbearing surface of the calcaneus from the anatomical axis of the tibia is typically described, but an angle of the calcaneus might be considered as well. As described in a number of the rationale

de Cesar Netto et al 3

statements, ideal radiographic hindfoot position and clinical hindfoot position might not always be the same.

Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation,

University of Iowa, Iowa City, IA, USAEmail: cesar-netto@uiowa.edu

Jonathan T. Deland, MDHospital for Special Surgery, New York, NY, USA

Scott J. Ellis, MD, Hospital for Special Surgery, New York, NY, USA

Acknowledgments

We thank David B. Thordarson and Jeffrey Johnson for helping to put together the glossary and nomenclature definitions. We also acknowledge the crucial work of Katrina E. Bang and Jonathan Day, research assistants of, respectively, the University of Iowa and the Hospital for Special Surgery, for helping us to record and keep the track of all information discussed. We also thank Paragon 28 and TriMed for the support with food and beverages during the 2 days of the consensus meeting.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

References

1. Aiyer A, Raikin S, Parvizi J. 2018 International consensus meeting on musculoskeletal infection: findings of the Foot and Ankle Work Group. Foot Ankle Int. 2019;40(1)(suppl):1S.

2. Murawski CD, Hogan MV, Thordarson DB, Stone JW, Ferkel RD, Kennedy JG. Editorial. Foot Ankle Int. 2018;39(1)(suppl):1S-2S.

https://doi.org/10.1177/1071100720950722

Foot & Ankle International® 1 –6© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950722journals.sagepub.com/home/fai

Topical Review

950722 FAIXXX10.1177/1071100720950722Foot & Ankle InternationalMyerson et alresearch-article2020

Classification and Nomenclature: Progressive Collapsing Foot Deformity

Mark S. Myerson, MD1, David Thordarson, MD2, Jeffrey E. Johnson, MD3 , Beat Hintermann, MD4, Bruce J. Sangeorzan, MD5, Jonathan T. Deland, MD6, Lew C. Schon, MD7,8,9,10, Scott J. Ellis, MD6 , and Cesar de Cesar Netto, MD, PhD11

AbstractRecommendation: The historical nomenclature for the adult acquired flatfoot deformity (AAFD) is confusing, at times called posterior tibial tendon dysfunction (PTTD), the adult flexible flatfoot deformity, posterior tibial tendon rupture, peritalar instability and peritalar subluxation (PTS), and progressive talipes equinovalgus. Many but not all of these deformities are associated with a rupture of the posterior tibial tendon (PTT), and some of these are associated with deformities either primarily or secondarily in the midfoot or ankle. There is similar inconsistency with the use of classification schemata for these deformities, and from the first introduced by Johnson and Strom (1989), and then modified by Myerson (1997), there have been many attempts to provide a more comprehensive classification system. However, although these newer more complete classification systems have addressed some of the anatomic variations of deformities encountered, none of the above have ever been validated. The proposed system better incorporates the most recent data and understanding of the condition and better allows for standardization of reporting. In light of this information, the consensus group proposes the adoption of the nomenclature “Progressive Collapsing Foot Deformity” (PCFD) and a new classification system aiming at summarizing recent data published on the subject and to standardize data reporting regarding this complex 3-dimensional deformity.Level of Evidence: Level V, consensus, expert opinion.Consensus Statements Voted:CONSENSUS STATEMENT ONE: We will rename the condition to Progressive Collapsing Foot Deformity (PCFD), a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot varus.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT TWO: Our current classification systems are incomplete or outdated.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT THREE: MRI findings should be part of a new classification system.Delegate vote: agree, 33% (3/9); disagree, 67% (6/9); abstain, 0%.(Weak negative consensus)CONSENSUS STATEMENT FOUR: Weightbearing CT (WBCT) findings should be part of a new classification system.Delegate vote: agree, 56% (5/9); disagree, 44% (4/9); abstain, 0%.(Weak consensus)CONSENSUS STATEMENT FIVE: A new classification system is proposed and should be used to stage the deformity clinically and to define treatment.Delegate vote: agree, 89% (8/9); abstain, 11% (1/9).(Strong consensus)

Keywords: flatfoot, adult acquired flatfoot deformity, AAFD, classification flatfoot, progressive collapsing foot deformity, PCFD, rupture posterior tibial tendon (PTT)

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Rationale

Classification Systems

The clinical applicability of any classification system depends to a large extent on its usefulness in planning treat-ment, and it is with this goal in mind that any system should be developed. The purpose is ultimately to make treatment decisions more rational and individualized to each patient’s particular anatomic pathology. An ideal classification sys-tem should also be reproducible, understandable by all sur-geons, provide a prognosis, and also allow researchers to more effectively share data.

In 1989, Johnson and Strom proposed a 3-stage classifica-tion associated with dysfunction and ultimate rupture of the posterior tibial tendon calling it PTTD, and which was based on the condition of the PTT, the position of the hindfoot, and flexibility of the deformity (Table 1).7 In this article, a fourth stage was alluded to as a fixed rigid valgus deformity associ-ated with arthritis of the ankle requiring a TTC arthrodesis, and in 1997 this was formally added by Myerson as a stage IV deformity.8 The latter was subsequently divided in a revised classification by Bluman and Myerson into IV-A associated with supple tibiotalar valgus, and IV-B associated with rigid deformities.2 It was also recognized by these authors that a valgus deformity of the tibiotalar joint caused by a rupture of the deltoid ligament is not necessarily associ-ated with a rupture of the posterior tibial tendon (PTT). The latter modified classification system is the one that was voted most used by the experts in our study group.

In the 1997 manuscript, Myerson incorrectly described this as a “continuum of PTT dysfunction” noting that “any grading or staging system of this dysfunction is somewhat arbitrary.”8 The stages of deformity in any classification system do not exist on a continuous spectrum because pro-gression is not linear and may affect different regions of the foot and ankle with or without a rupture of the PTT. Deformity may, for example, include the tarsometatarsal (TMT) joints, the naviculocuneiform (NC) joints, and may be associated with a rupture or attenuation of the plantar fascia, the spring, and/or the deltoid ligament in the absence of a PTT rupture.5

Furthermore, it is accepted that stage I disease with no deformity regardless of the pathology of the PTT may never progress to stage II, and similarly, a stage II may not progress to a stage III deformity.1,10,14 This has implications for treatment, which the surgeon should base on the contin-ued presence of pain despite adequate nonoperative care, and not because a more advanced stage may develop. The only exception to this may be a stage IV-A deformity that can be treated with joint sparing procedures prior to inevi-tably progressing to a stage IV-B associated with ankle joint arthritis.

Since Johnson and Strom’s initial 1989 classification and the modification by Myerson in 1997,7,8 an increas-ingly complex combination of deformities of the midfoot, hindfoot, and ankle has been recognized in association with dysfunction and rupture of the PTT, not addressed by these classifications. More importantly, those classification sys-tems did not describe variations, for example, the wide array of treatment options for the flexible foot deformity. Recognizing this wide variation in mobility of the medial column, abduction of the foot, and forefoot varus, Bluman et al2 introduced a revised classification scheme in 2007 (Table 2). These authors took the original Johnson and Strom classification for flatfoot deformity and revised it into a system encompassing the various presentations seen within each stage, with the most obvious expansion dealing with stage II disease. Table 2 summarizes the classification of Bluman et al, including pertinent findings and sugges-tions for treatment for each of the described stages.

It is recognized, however, that the classification by Bluman et al is also limited and does not sufficiently describe nor include the anatomic and sufficient radio-graphic details of deformity. Parsons et al reported their results of treating stage II deformity with a modified Cobb technique and a calcaneus osteotomy, and introduced a modification to the Johnson classification by focusing on the extent of varus of the midfoot and forefoot.9 They believed that stage II covers a wide spectrum of deformity ranging from a mobile hindfoot, midfoot, and forefoot to a later stage where a fixed varus deformity in the midfoot and forefoot is present, either correctible or fixed, and greater or

1Department of Orthopedic Surgery, University of Colorado School of Medicine, 12631 East 17th Avenue, B202, Aurora, CO 80045, USA.2Cedars-Sinai Medical Center, Los Angeles, CA, USA3Washington University School of Medicine, MO, USA4Kantonspital Baselland, Liestal, Switzerland5University of Washington, Seattle, WA, USA6Hospital for Special Surgery, New York, NY, USA7Mercy Medical Center, Baltimore, MD, USA8New York University Grossman School of Medicine, New York, NY, USA9Johns Hopkins School of Medicine, Baltimore, MD, USA 10Georgetown School of Medicine, Washington, DC, USA11Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA

Corresponding Author:Cesar de Cesar Netto, University of Iowa, Department of Orthopaedics and Rehabilitation, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City-IA, 52242, USA. Email: cesar-netto@uiowa.edu

Myerson et al 3

Table 1. Johnson and Strom Classification, 1989.7

VariableStage I

mild, medial painStage II

moderate, medial painStage III

severe, medial, and lateral pain

ExaminationSwelling and tenderness

Mild swelling and tenderness along PTT

Moderate swelling and tenderness along PTT

Not much swelling but markedtenderness along PTT

Heel-rise test Mild weakness Marked weakness Marked weakness‘‘Too many toes’’ sign Absent Present PresentDeformity Absent Present (flexible) Present (fixed)Pathologic features Normal tendon length

paratendinitisElongated with

longitudinal tearsDisrupted with visible tears

Images No changes Gross deformity Deformity and diffuse arthritic changesTreatment Conservative, tenosynovectomy FDL transfer Triple arthrodesis

Abbreviations: FDL, flexor digitorum longus; PTT, posterior tibial tendon.

Table 2. Bluman et al Classification, 2007.2

Stage Substage Most characteristic clinical findingsMost characteristic radiographic findings Treatment

1 A Normal anatomyTenderness along PTT

Normal Immobilization, NSAIDs, cryotherapyOrthosesTenosynovectomy±Systemic disease-specific pharmacotherapy

B Normal anatomyTenderness along PTT

Normal Immobilization, NSAIDs, cryotherapyOrthosesTenosynovectomy

C Slight HF valgusTenderness along PTT

Slight HF valgus Immobilization, NSAIDs, cryotherapyOrthosesTenosynovectomy

II A1 Supple HF valgusFlexible forefoot varusPossible pain along PTT

HF valgusMeary line disruptionLoss of calcaneal pitch

OrthosesMedial displacement calcaneal osteotomyTAL or Strayer and FDL transfer if deformity

corrects only with ankle plantarflexion A2 Supple HF valgus

Fixed forefoot varusPossible pain along PTT

HF valgusMeary line disruptionLoss of calcaneal pitch

OrthosesMedial displacement calcaneal osteotomy and

FDL transferCotton osteoectomy

B Supple HF valgusForefoot abduction

HF valgusTalonavicular uncoveringForefoot abduction

OrthosesMedial displacement calcaneal osteotomy and

FDL transferLateral column lengthening

C Supple HF valgusFixed forefoot varusMedial column instabilityFirst-ray dorsiflexion with HF correctionSinus tarsi pain

HF valgusFirst TMT joint plantar

gapping

Medial displacement calcaneal osteotomy and FDL transfer

Cotton osteotomy or medial column fusion

III A Rigid HF valgusPain in sinus tarsi

Subtalar joint space lossHF valgusAngle of Gissane sclerosis

Custom bracing if not operative candidateTriple arthrodesis

B Rigid HF valgusForefoot abductionPain in sinus tarsi

Subtalar joint space lossHF valgusAngle of Gissane sclerosisForefoot abduction

Custom bracing if not operative candidateTriple arthrodesis ± lateral column

lengthening

IV A Supple tibiotalar valgus Tibiotalar valgusHF valgus

Surgery for HF valgus and associated deformityDeltoid reconstruction

B Rigid tibiotalar valgus Tibiotalar valgusHF valgus

TTC fusion or pantalar fusion

Abbreviations: FDL, flexor digitorum longus; HF, hind foot; NSAIDs, nonsteroidal anti-inflammatory drugs; PTT, posterior tibial tendon; TAL, tendo-Achilles lengthening; TMT, tarsometatarsal; TTC, tibiotalocalcaneal.

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less than 15 degrees. The focus on varus had already been covered to a large extent by the Bluman classification2; however, Parsons et al believed that a more advanced stage II disease may be associated with a mobile and correctable hindfoot, where resting forefoot varus may not be correct-able.9 They concluded that it would be advantageous to address the deformity operatively before this later phase of fixed severe forefoot varus was reached, but recognized that this would have to be confirmed by further studies. As stated already above, because disease is not on a continuum, the latter statement would be difficult to prove.

The midfoot has received more attention in recent clas-sifications. Richter and Zech focused on the midfoot, spe-cifically noting the TMT angles that were defined to be negative for abduction in the anteroposterior radiograph and for dorsiflexion on the lateral radiographs.11 They pro-posed a TMT Index that was defined as the sum of the anteroposterior and lateral TMT angles. They believed that the function of the PTT did not highly correlate with joint stiffness because they found collapsed flat feet that were not stiff, and stiff feet without any rupture of the PTT. A more recent classification system, also with a focus on the mid-foot, was introduced by Raikin et al10 called the RAM clas-sification, which divided the AAFD deformity into the individual components involved in the disease process. These authors maintained the original grade I to III system as well as the (a) and (b) subclassification introduced by Bluman et al,2 but applied these separately to the rearfoot (R), ankle (A), and midfoot (M). They noted that varus and abduction most commonly occurs at the transverse tarsal joints, and that this deformity may also develop from the midfoot. It still remains unclear, however, if collapse and

varus of the midfoot, whether at the naviculocuneiform (NC) and TMT articulations, occurs as a primary deformity or secondary to the chronic hindfoot deformity and rupture or attenuation of the secondary stabilizers of the arch. This classification system may be useful for a surgeon who is not familiar with treatment algorithms but does not change the need to evaluate each deformity individually because the ankle, hindfoot, and midfoot must always be assessed inde-pendently of each other.

Finally, it is unclear whether the entity classified by Johnson and Strom as stage I PTTD ought to be included in the description of PCFD. It is not clear what this stage refers to, nor does stage I disease inevitably progress to stage II, and frequently, this is a stable process associated with minor tendon inflammation and/or degeneration.14 In our consen-sus group, the most important finding of stage I disease was the presence of PTT pain (5/9, 56%), followed by gastroc-nemius tightness and mild hindfoot valgus (2/9, 22%). Some felt that there was no valid description of stage I dis-ease, and only 56% (5/9) felt that there was some indication for surgery in this stage. The surgeries that were indicated were a gastrocnemius recession, PTT debridement, and cal-caneus osteotomy (5/9, 55%), followed by a medial cunei-form osteotomy, PTT tenosynovectomy, and arthroereisis (1/9, 11%).

Grading a patient according to any classification system requires a thorough history and physical examination, but also weightbearing conventional radiographic evaluation, which could also include more modern technology such as weightbearing computed tomography (WBCT) scan.

The expert consensus group agreed that a new classifica-tion system should be proposed (Table 3). This

Table 3. Consensus Group Classification of Progressive Collapsing Foot Deformity.

Stage of the deformity

Stage I (flexible) Stage II (rigid)

Types of deformity (classes – isolated or combined)

Deformity type/location Consistent clinical/radiographic findings

Class A Hindfoot valgus deformity Hindfoot valgus alignmentIncreased hindfoot moment arm, hindfoot alignment angle,

foot and ankle offsetClass B Midfoot/forefoot abduction

deformityDecreased talar head coverageIncreased talonavicular coverage anglePresence of sinus tarsi impingement

Class C Forefoot varus deformity/medial column instability

Increased talus–first metatarsal anglePlantar gapping first TMT joint/NC jointsClinical forefoot varus

Class D Peritalar subluxation/dislocation Significant subtalar joint subluxation/subfibular impingementClass E Ankle instability Valgus tilting of the ankle joint

Abbreviations: NC, naviculocuneiform; TMT, tarsometatarsal.

Myerson et al 5

new classification scheme is presented and is based on the flexibility, and the type and location of deformity only, and therefore does not include the original stage I disease state. It is based on deformities that are either flexible (stage I) or rigid (stage II) and further described by adding 1 or more (isolated or combined) types of present deformities (classes A-E):

Presented below are examples of how the classification may be used:

•• A 53-year-old woman patient presents with a flat-foot, and on clinical examination, the hindfoot and midfoot are flexible (stage 1). The hindfoot is in val-gus (A), flexible forefoot varus is present (C), and there is no abduction deformity of the forefoot or peritalar instability. On weightbearing radiographs, there is slight valgus deformity of the ankle joint that is reducible on clinical examination (E): This defor-mity would be classified as 1ACE.

•• A 34-year-old woman presents with a flatfoot defor-mity. On clinical examination, the hindfoot is flexible (1A), and when reducing the subtalar joint into a neu-tral position, there is fixed forefoot supination of 25 degrees present (2C). There is considerable pain in the sinus tarsi and under the tip of the fibula indicating peritalar subluxation (1D). The ankle is stable both on clinical examination and on weightbearing radio-graphs: This deformity would be classified as 1AD2C.

•• A 64-year-old man presents with a painful flatfoot. On clinical examination, the hindfoot is in valgus and the subtalar joint is rigid to manipulation (2A). There is instability at the first tarsometatarsal joint with gapping on the lateral weightbearing radio-graph, but the medial column is not rigid nor is there any fixed forefoot varus (1C). There is abduction of the forefoot that cannot be reduced (2B) but no sinus tarsi impingement to indicate severe peritalar insta-bility either clinically or on weightbearing radio-graphs. The ankle is stable both on clinical examination and on weightbearing radiographs: This deformity would be classified as 2AB1C.

Terminology

Over the years, our understanding of the biomechanics of the medial longitudinal arch and development of the flat-foot (currently termed the adult-acquired flatfoot deformity [AAFD] because of the various causes of the flatfoot in addition to the PTT rupture) has evolved. Numerous inves-tigators have since proposed variations of Johnson and Strom’s system in an effort to encompass the expanded spectrum of AAFD and its associated deformities.2,7,8,10 All continue to maintain their system’s overall structure and

the PTTs central role in the development of the deformity but have added new subclassifications. These alternate, more comprehensive systems increasingly acknowledge the involvement of the midfoot in the development of the AAFD, while noting the progressive effect of a dysfunc-tional PTT on the rearfoot and subsequently the ankle.

However, the anatomy of the flexible AAFD includes far more than a rupture of the PTT, most importantly the spring and deltoid ligaments,5 specifically the articular support provided by the sling effect of the spring ligament to the TN joint, which must be evaluated and always be taken into consideration when evaluating any AAFD. The relevance of the spring ligament has been neglected with respect to descriptive terminology and not included in classification systems over the decades.3,4,6,13 The first to recognize the potential for this instability was Johnson in 1989 in a sim-plistic illustration that highlighted the shifts of the navicular and calcaneus around a fixed talus.7 The term peritalar subluxation (PTS) should be attributed to Hansen and col-leagues, who detailed the anatomic and biomechanical changes that take place in the hindfoot leading to the flat-foot.12 Dorsal translation of the navicular relative to the talus occurs with a wedge-shaped opening on the plantar surface of the TN joint, and this, coupled with uncovering of the head of the talus secondary to lateral subluxation of the navicular on the talus, has led to the introduction of the term dorsolateral PTS of the foot to describe the abnormal biplanar relationship between the talus and the navicular resulting from dysfunction or rupture of the PTT.12

The consensus group has recommended renaming the condition to Progressive Collapsing Foot Deformity (PCFD), a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and mid-foot varus. We use the words progressive and collapsing because they give a better idea of the worsening and evolving nature of the complexity of this 3D deformity. This will avoid the misleading and underestimated nature of prior terminology. It does not include the use of the term posterior tibial tendon, because the tendon itself is not the problem. It is also preferable not to use acquired flatfoot as the terminology, because a lot of people are born with flatfeet and are never symptomatic, and the flat-tening of the arch is only one of the 3-dimensional compo-nents of the deformity.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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ORCID iDs

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

References

1. Abousayed MM, Tartaglione JP, Rosenbaum AJ, Dipreta JA. Classifications in brief: Johnson and Strom Classification of Adult-acquired Flatfoot Deformity. Clin Orthop Relat Res. 2016;474(2):588-593.

2. Bluman EM, Title CI, Myerson MS. Posterior tibial tendon rupture: a refined classification system. Foot Ankle Clin. 2007;12(2):233-249, v.

3. Brodell JD Jr, MacDonald A, Perkins JA, Deland JT, Oh I. Deltoid-Spring ligament reconstruction in adult acquired flat-foot deformity with medial peritalar instability. Foot Ankle Int. 2019;40(7):753-761.

4. Deland JT. The adult acquired flatfoot and spring ligament complex. Pathology and implications for treatment. Foot Ankle Clin. 2001;6(1):129-135, vii.

5. Deland JT, de Asla RJ, Sung IH, Ernberg LA, Potter HG. Posterior tibial tendon insufficiency: which ligaments are involved? Foot Ankle Int. 2005;26(6):427-435.

6. Gazdag AR, Cracchiolo A 3rd. Rupture of the posterior tibial tendon. Evaluation of injury of the spring ligament and clini-cal assessment of tendon transfer and ligament repair. J Bone Joint Surg Am. 1997;79(5):675-681.

7. Johnson KA, Strom DE. Tibialis posterior tendon dysfunc-tion. Clin Orthop Relat Res. 1989;239:196-206.

8. Myerson MS. Adult acquired flatfoot deformity: treatment of dysfunction of the posterior tibial tendon. Instr Course Lect. 1997;46:393-405.

9. Parsons S, Naim S, Richards PJ, McBride D. Correction and prevention of deformity in type II tibialis posterior dysfunction. Clin Orthop Relat Res. 2010;468(4):1025-1032.

10. Raikin SM, Winters BS, Daniel JN. The RAM classification: a novel, systematic approach to the adult-acquired flatfoot. Foot Ankle Clin. 2012;17(2):169-181.

11. Richter M, Zech S. Lengthening osteotomy of the calca-neus and flexor digitorum longus tendon transfer in flexible flatfoot deformity improves talo-1st metatarsal-Index, clini-cal outcome and pedographic parameter. Foot Ankle Surg. 2013;19(1):56-61.

12. Toolan BC, Sangeorzan BJ, Hansen ST Jr. Complex recon-struction for the treatment of dorsolateral peritalar sublux-ation of the foot. Early results after distraction arthrodesis of the calcaneocuboid joint in conjunction with stabilization of, and transfer of the flexor digitorum longus tendon to, the mid-foot to treat acquired pes planovalgus in adults. J Bone Joint Surg Am. 1999;81(11):1545-1560.

13. Van Boerum DH, Sangeorzan BJ. Biomechanics and patho-physiology of flat foot. Foot Ankle Clin. 2003;8(3):419-430.

14. Wake J, Martin K. Posterior tibial tendon endoscopic debride-ment for stage I and II posterior tibial tendon dysfunction. Arthrosc Tech. 2017;6(5):e2019-e2022.

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Topical Review

950732 FAIXXX10.1177/1071100720950732Foot & Ankle InternationalThordarson et alresearch-article2020

Consensus for the Indication of Lateral Column Lengthening in the Treatment of Progressive Collapsing Foot Deformity

David Thordarson, MD1, Lew C. Schon, MD2,3,4,5, Cesar de Cesar Netto, MD, PhD6 , Jonathan T. Deland, MD7, Scott J. Ellis, MD7 , Jeffrey E. Johnson, MD8 , Mark S. Myerson, MD9, Bruce J. Sangeorzan, MD10, and Beat Hintermann, MD11

AbstractRecommendation: Progressive collapsing foot deformity (PCFD) is a complex 3D deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot supination. Although a medial displacement calcaneal osteotomy can correct heel valgus, it has far less ability to correct forefoot abduction. More severe forefoot abduction, most frequently measured preoperatively by assessing talonavicular coverage on an anteroposterior (AP) weightbearing conventional radiographic view of the foot, can be more effectively corrected with a lateral column lengthening procedure than by other osteotomies in the foot. Care must be taken intraoperatively to not overcorrect the deformity by restricting passive eversion of the subtalar joint or causing adduction at the talonavicular joint on simulated AP weightbearing fluoroscopic imaging. Overcorrection can lead to lateral column overload with persistent lateral midfoot pain. The typical amount of lengthening of the lateral column is between 5 and 10 mm.Level of Evidence: Level V, consensus, expert opinion.CONSENSUS STATEMENT ONE: Lateral column lengthening (LCL) procedure is recommended when the amount of talonavicular joint uncoverage is above 40%. The amount of lengthening needed in the lateral column should be judged intraoperatively by the amount of correction of the uncoverage and by adequate residual passive eversion range of motion of the subtalar joint.Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9).(Strong consensus)CONSENSUS STATEMENT TWO: When titrating the amount of correction of abduction deformity intraoperatively, the presence of adduction at the talonavicular joint on simulated weightbearing fluoroscopic imaging is an important sign of hypercorrection and higher risk for lateral column overload.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT THREE: The typical range for performing a lateral column lengthening is between 5 and 10 mm to achieve an adequate amount of talonavicular coverage.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, reconstruction, osteotomy, Evan’s osteotomy, lateral column lengthening, LCL, progressive collapsing foot deformity, PCFD

Rationale

Lateral column lengthening (LCL) has been used in progres-sive collapsing foot deformity (PCFD) surgery for abduction deformity at the talonavicular joint. It is uncommonly per-formed in isolation but is often used with other PCFD correc-tive procedures which will be covered in other sections of this consensus statement. The question of which corrective procedures are required to achieve an optimal operative result

for a specific patient with a given deformity has not been answered. Although many decisions are made intraopera-tively about the specific procedures to be performed, preop-erative clinical and weightbearing conventional radiographic evaluation can help to determine if an LCL would be appro-priate in the operative correction of a deformity.

A careful clinical evaluation with appropriate history and physical examination is an important starting point. Clinically, the visible severity of the forefoot abduction can

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be helpful in determining if someone may benefit from an LCL. As with all the reconstructive options, the deformity must be flexible in order to consider a corrective rather a fusion type of operation. Severity of the deformity is par-ticularly important. The most severe deformities have a greater likelihood of being stiff or, if they are flexible, sur-gery can still fail to adequately correct the abduction and/or plantarflexion deformity of the TN joint.

In general, although the severity of the deformity and amount of foot abduction is evident on clinical examination, most surgeons use weightbearing conventional radiographic parameters to help guide their decision making. Many different radiographic measures have been described. Consistent with previous authors, we agree that the talonavicular coverage angle on an anteroposterior (AP) weightbearing view of the foot is most helpful.22 The consensus is consistent with studies on LCL indications.4,23 Other measures of a PCFD that have been discussed regarding the necessity for an LCL include the lateral incongruency angle, AP talar–first metatarsal angle, and talar–second metatarsal angle.1,14,25 Although lateral weight-bearing radiographs of the foot are important for assessing the degree of talonavicular (TN), naviculocuneiform (NC), and first tarsometatarsal (TMT) plantar sagging, in general none of these measures impact the necessity for an LCL. LCL can in some feet correct the plantar TN sag but in others not be as effective in correcting the sagittal plane component of the deformity. With a mild to moderate TN sag, LCL will often give adequate correction in the sagittal plane, but with severe plan-tarflexion, inadequate correction is likely. Surgeons are cau-tioned that if the patient does not apply full weight to the foot during image acquisition and does not let the arch sag, conven-tional weightbearing radiographs can cause the surgeon to underestimate the deformity. This should be checked particu-larly if the images do not match the clinical deformity. Weightbearing Saltzman axial heel views and ankle radiographs are also important for fully assessing a PCFD,21 but they do not influence the decision to perform an LCL. Advanced imaging studies such as weightbearing CT scans and MRI have a role in evaluating ACFD but likewise generally do not influence the decision whether an LCL is indicated.

In general, LCL procedures are lengthening osteotomies of the anterior or midportion of the calcaneus. Although

distraction arthrodesis of the calcaneocuboid joint has been described, it does lead to more stiffness because of fusion of a hindfoot joint and has a higher rate of nonunion.13,18 The most commonly performed osteotomy is the Evan lengthen-ing osteotomy performed parallel and slightly more than 1 cm posterior to the calcaneocuboid joint.1,18,19 Other oste-otomies described include the central Hintermann9,15 and central/step-cut Vander Griend osteotomies.5,10 Each of these osteotomies have advocates and none has been found to be consistently more successful than the others.23 In gen-eral, the literature supports that each osteotomy is designed to achieve the same goal of successfully lengthening the calcaneus to correct the deformity as much as possible.

Our consensus group most often uses a pre-shaped allograft wedge for the osteotomy, which avoids the morbid-ity of autograft and allows one to use trial wedges while sequentially lengthening through the osteotomy to maximize the chances for an ideal graft size.7 Some studies have shown similar union rates with auto- vs allograft, with some sur-geons still preferring autograft.6,11,24 Other surgeons have used trabecular metal wedges with similar good outcomes to allograft.12

Performing the correct amount of lengthening is a critical portion of the operation.1,3,4 The amount will vary for each case but the range of ideal graft size in our consensus group was 5-10 mm. A pin distractor can be placed across the oste-otomy and opened gradually to allow for correction of the forefoot abduction. The ideal amount of correction is assessed both visually and with a simulated AP weightbear-ing fluoroscopic view. Once an ideal amount of correction has been achieved, passive hindfoot motion, especially ever-sion, should be assessed. It is the opinion of the majority of surgeons in this group that if it is significantly restricted, then the amount of distraction at the osteotomy site needs to be decreased until the passive eversion is relatively unre-stricted. Overcorrection will lead to a higher rate of lateral column pain and increased lateral foot pressures with a higher rate of patient dissatisfaction.2,8,20 When using precut allograft or metallic wedges, trial wedges are available to get the most accurate size measurement of the actual wedge to be implanted. Most surgeons agree internal fixation should be used to stabilize the graft in the form of screws or plates.

1Cedars-Sinai Medical Center, Los Angeles, CA, USA2Mercy Medical Center, Baltimore, MD, USA3New York University Grossman School of Medicine, New York, NY, USA 4Johns Hopkins School of Medicine, Baltimore, MD, USA 5Georgetown School of Medicine, Washington, DC, USA6Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA7Hospital for Special Surgery, New York, NY, USA8Washington University School of Medicine, St. Louis, MO, USA9Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA10University of Washington, Seattle, WA, USA11Kantonspital Baselland, Liestal, Switzerland

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Thordarson et al 3

Although many studies have been published on the opera-tive management of ACFD, almost all of them appropriately report on combinations of procedures used to correct this complex deformity. This feature of the ACFD literature makes it difficult to separate the contributions of the various components of each surgery to the final outcome. However, the literature does support that LCL has a much higher rate of failure with overcorrection either radiographically, that is, adduction of the forefoot, or if it results in limited hindfoot eversion. Conversely, the best results are achieved when the deformity is fully corrected16,17; that is, aim for ideal radio-graphic correction but be prepared to accept less than perfect alignment if it leads to stiffness in eversion.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

References

1. Chan JY, Greenfield ST, Soukup DS, Do HT, Deland JT, Ellis SJ. Contribution of lateral column lengthening to cor-rection of forefoot abduction in stage IIb adult acquired flat-foot deformity reconstruction. Foot Ankle Int. 2015;36(12): 1400-1411.

2. Conti MS, Chan JY, Do HT, Ellis SJ, Deland JT. Correlation of postoperative midfoot position with outcome following reconstruction of the stage II adult acquired flatfoot defor-mity. Foot Ankle Int. 2015;36(3):239-247.

3. Conti MS, Deland JT, Ellis SJ. Stage IIB flatfoot reconstruction using literature-based equations for heel slide and lateral column lengthening. Tech Foot Ankle Surg. 2017;16(4):153-166.

4. Deland JT. Adult-acquired flatfoot deformity. J Am Acad Orthop Surg. 2008;16(7):399-406.

5. Demetracopoulos CA, Nair P, Malzberg A, Deland JT. Outcomes of a stepcut lengthening calcaneal osteotomy for adult-acquired flatfoot deformity. Foot Ankle Int. 2015;36(7):749-755.

6. Dolan CM, Henning JA, Anderson JG, Bohay DR, Kornmesser MJ, Endres TJ. Randomized prospective study comparing tri-cortical iliac crest autograft to allograft in the lateral col-umn lengthening component for operative correction of adult acquired flatfoot deformity. Foot Ankle Int. 2007;28(1):8-12.

7. Ellis SJ, Williams BR, Garg R, Campbell G, Pavlov H, Deland JT. Incidence of plantar lateral foot pain before and after the use of trial metal wedges in lateral column lengthen-ing. Foot Ankle Int. 2011;32(7):665-673.

8. Ellis SJ, Yu JC, Johnson AH, Elliott A, O’Malley M, Deland J. Plantar pressures in patients with and without lateral foot pain after lateral column lengthening. J Bone Joint Surg Am. 2010;92(1):81-91.

9. Ettinger S, Mattinger T, Stukenborg-Colsman C, et al. Outcomes of Evans versus Hintermann calcaneal lengthening osteotomy for flexible flatfoot. Foot Ankle Int. 2019;40(6):661-671.

10. Griend RV. Lateral column lengthening using a “Z” osteotomy of the calcaneus. Tech Foot Ankle Surg. 2008;7(4):257-263.

11. Grier KM, Walling AK. The use of tricortical autograft ver-sus allograft in lateral column lengthening for adult acquired flatfoot deformity: an analysis of union rates and complica-tions. Foot Ankle Int. 2010;31(9):760-769.

12. Gross CE, Huh J, Gray J, Demetracopoulos C, Nunley JA. Radiographic outcomes following lateral column lengthening with a porous titanium wedge. Foot Ankle Int. 2015;36(8): 953-960.

13. Grunander TR, Thordarson DB. Results of calcaneocuboid distraction arthrodesis. Foot Ankle Surg. 2012;18(1):15-18.

14. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis WH, Manoli A 2nd. Symposium: Adult acquired flatfoot deformity. Foot Ankle Int. 2011;32(1):95-111.

15. Hintermann B, Valderrabano V, Kundert HP. Lateral column lengthening by calcaneal osteotomy combined with soft tissue reconstruction for treatment of severe posterior tibial tendon dysfunction. Methods and preliminary results [in German]. Orthopade. 1999;28(9):760-769.

16. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc-tion. Foot Ankle Clin. 2017;22(3):613-624.

17. Iossi M, Johnson JE, McCormick JJ, Klein SE. Short-term radiographic analysis of operative correction of adult acquired flatfoot deformity. Foot Ankle Int. 2013;34(6):781-791.

18. Kitaoka HB, Kura H, Luo ZP, An KN. Calcaneocuboid distraction arthrodesis for posterior tibial tendon dysfunc-tion and flatfoot: a cadaveric study. Clin Orthop Relat Res. 2000;381:241-247.

19. Mosier-LaClair S, Pomeroy G, Manoli A 2nd. Operative treatment of the difficult stage 2 adult acquired flatfoot defor-mity. Foot Ankle Clin. 2001;6(1):95-119.

20. Oh I, Imhauser C, Choi D, Williams B, Ellis S, Deland J. Sensitivity of plantar pressure and talonavicular alignment to lateral column lengthening in flatfoot reconstruction. J Bone Joint Surg Am. 2013;95(12):1094-100.

21. Saltzman CL, el-Khoury GY. The hindfoot alignment view. Foot Ankle Int. 1995;16(9):572-576.

22. Sangeorzan BJ, Mosca V, Hansen ST Jr. Effect of calcaneal lengthening on relationships among the hindfoot, midfoot, and forefoot. Foot Ankle. 1993;14(3):136-141.

23. Saunders SM, Ellis SJ, Demetracopoulos CA, Marinescu A, Burkett J, Deland JT. Comparative outcomes between step-cut lengthening calcaneal osteotomy vs traditional evans oste-otomy for stage IIB adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(1):18-27.

24. Vosseller JT, Ellis SJ, O’Malley MJ, et al. Autograft and allograft unite similarly in lateral column lengthening for adult acquired flatfoot deformity. HSS J. 2013;9(1):6-11.

25. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of the adult acquired flatfoot deformity. Curr Rev Musculoskelet Med. 2013;6(4):294-303.

https://doi.org/10.1177/1071100720950734

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Topical Review

Consensus Statements Voted

1. CONSENSUS STATEMENT 1—The following WEIGHTBEARING conventional radiographs (CRs) are considered mandatory by the consensus group in the assessment of progressive collapsing foot deformity (PCFD) patients: anteroposterior (AP) foot, AP or mortise ankle, lateral foot. The consensus group also strongly recommends a hind­foot alignment view when available.Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%(Unanimous, Strongest Consensus)

2. CONSENSUS STATEMENT 2—If WEIGHT­BEARING computed tomography (CT) imaging available, the consensus group strongly recommends its use for surgical planning of PCFD patients.Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%(Unanimous, Strongest Consensus)

3. CONSENSUS STATEMENT 3—The presence of important WEIGHTBEARING CR/WEIGHT­BEARING CT findings to be assessed includes sinus

tarsi impingement, increased valgus inclination of the posterior facet of the subtalar joint, subluxation of the subtalar joint at the posterior and/or middle facet, and subfibular impingement.

950734 FAIXXX10.1177/1071100720950734Foot & Ankle Internationalde Cesar Netto et alreview-article2020

1Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA2Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA3Hospital for Special Surgery, New York, NY, USA4Kantonspital Baselland, Liestal, Switzerland5Washington University School of Medicine, St. Louis, MO, USA6University of Washington, Seattle, WA, USA7Mercy Medical Center, Baltimore, MD, USA8New York University Grossman School of Medicine, New York, NY, USA 9Johns Hopkins School of Medicine, Baltimore, MD, USA 10Georgetown School of Medicine, Washington, DC, USA11Cedars-Sinai Medical Center, Los Angeles, CA, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Consensus for the Use of Weightbearing CT in the Assessment of Progressive Collapsing Foot Deformity

Cesar de Cesar Netto, MD, PhD1 , Mark S. Myerson, MD2, Jonathan Day, MS3 , Scott J. Ellis, MD3 , Beat Hintermann, MD4, Jeffrey E. Johnson, MD5 , Bruce J. Sangeorzan, MD6, Lew C. Schon, MD7,8,9,10, David Thordarson, MD11, and Jonathan T. Deland, MD3

AbstractRecommendation: There is evidence that the use of WEIGHTBEARING imaging aids in the assessment of progressive collapsing foot deformity (PCFD). The following WEIGHTBEARING conventional radiographs (CRs) are necessary in the assessment of PCFD patients: anteroposterior (AP) foot, AP or mortise ankle, and lateral foot. If available, a hindfoot alignment view is strongly recommended. If available, WEIGHTBEARING computed tomography (CT) is strongly recommended for surgical planning. When WEIGHTBEARING CT is obtained, important findings to be assessed are sinus tarsi impingement, subfibular impingement, increased valgus inclination of the posterior facet of the subtalar joint, and subluxation of the subtalar joint at the posterior and/or middle facet.Level of Evidence: Level V, consensus, expert opinion.

Keywords: adult-acquired flatfoot deformity, AAFD, flatfoot, reconstruction, weightbearing CT, peritalar subluxation, PTS, progressive collapsing foot deformity, PCFD

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Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%(Unanimous, Strongest Consensus)

Rationale

WEIGHTBEARING conventional radiographs (CR) have been the mainstay of evaluating progressive collapsing foot deformity (PCFD), with several validated radiographic measurements described for its assessment and staging.6,26,30 In a blinded comparison of standing anteroposterior (AP) and lateral CR measurements, Younger et al30 demonstrated that several radiographic parameters, including talar–first metatarsal angle (Meary’s angle) and talonavicular (TN) coverage angle,27 can reliably and consistently differentiate between patients with symptomatic PCFD deformity and controls.30 In another study by Arangio et al,3 it was deter­mined that the lateral­medial cuneiform distance measured on lateral WEIGHTBEARING CR is a useful parameter that assesses severity of a flattened arch, with PCFD patients having a significantly flatter arch (11.04 mm) compared to healthy controls (18.38 mm). The authors concluded that decreased lateral­medial cuneiform distance is a strong indicator of PCFD. Furthermore, Sensiba et al28 demon­strated strong to almost perfect interobserver reliability for radiographic parameters made on WEIGHTBEARING CR AP (talar–second metatarsal angle), lateral (talar–first meta­tarsal angle, medial cuneiform/fifth metatarsal distance), and hindfoot alignment view (tibial/calcaneal displacement, calcaneal angulation), highlighting the usability and repro­ducibility of these measurements.

Several studies have also demonstrated the association between WEIGHTBEARING CR correction and improved patient­reported outcomes. One such study by Conti et al10 demonstrated that the cuneiform articular angle (CAA) on WEIGHTBEARING lateral CR significantly correlates with postoperative clinical outcomes. The authors found that patients with a CAA of greater than or equal to −2 degrees (mild plantarflexion) had superior patient­reported outcomes compared to patients with less than –2 degrees (moderate plantarflexion). In another study assessing hind­foot alignment correction on hindfoot alignment view, investigators not only demonstrated that a postoperative hindfoot moment arm (HMA) of 0 to 5 mm varus correlates with a clinically straight heel but also concluded that this correction results in the greatest improvement in patient­reported outcomes.9 Given the results of these studies, the expert consensus is that WEIGHTBEARING CRs are man­datory in the assessment of PCFD patients and that the min­imal assessment needed is composed of the following WEIGHTBEARING CRs: AP foot, AP or mortise ankle, and lateral foot. The consensus group also strongly recom­mends a hindfoot alignment view if available. Having these 3 or 4 WEIGHTBEARING CR incidences would allow adequate radiographic assessment as well as the calculation of most of the measurements usually used in the staging and

preoperative evaluation of PCFD patients. A list of the results of a survey regarding the most commonly used WEIGHTBEARING CR measurements performed by the consensus experts is presented in Figure 1. However, the recommended mandatory ones by the expert consensus group are the ones presented in Consensus Statement 1.

While WEIGHTBEARING CRs remain the gold standard given their availability and affordability, multiplanar imaging such as conventional computed tomography (CT) and WEIGHTBEARING CT offers several unique advantages, including improved spatial resolution that allows a multiplanar 3­dimensional assessment, minimizing rotational and posi­tional bias, as well as bony superimposition.4,5,11 In addition, studies have demonstrated the reliability and reproducibility of using WEIGHTBEARING CT in the evaluation of PCFD, highlighting its ability to better quantify structural deformity compared to CR and nonweightbearing (NWB) images.15­17,20,23,31 One such study prospectively compared 19 mea­surements taken on WEIGHTBEARING CT and nonweight­bearing in patients with flexible PCFD and concluded that while there was substantial intra­ and interobserver reliability in both modalities, WEIGHTBEARING CT images demon­strated a significantly better ability to detect severity of bony derangement in PCFD patients compared to nonweightbearing CT.16 In another study comparing radiographic measurements between WEIGHTBEARING CT and WEIGHTBEARING CR in patients with PCFD vs healthy controls, Haleem et al21 demonstrated that WEIGHTBEARING CT is more sensitive than CR in detecting significant deformity, including Meary’s angle and talonavicular coverage angle in PCFD patients. The authors concluded that WEIGHTBEARING CT is therefore a more informative tool for evaluating PCFD in the physiologic WEIGHTBEARING position compared to CR. Kunas et al22 have also demonstrated that when compared to conventional nonweightbearing CT, WEIGHTBEARING CT was more accurate in demonstrating pronounced deformity and increased hindfoot valgus in PCFD patients, since it shows the bone rela­tionship with the foot under physiological standing load. When comparing conventional CT and WEIGHTBEARING CT, Kunas et al22 have demonstrated that specifically on PCFD patients, WEIGHTBEARING CT imaging proved to be corre­lated more strongly with markers of the deformity than conven­tional CT by revealing more pronounced hindfoot valgus. The authors concluded that conventional nonweightbearing CT scans could be used to assess PCFD but not as a surrogate of WEIGHTBEARING CT, with possible underestimation of the deformity.22

One of the most important aspects of PCFD that has become much clearer and more easily and directly assessed with the advent of WEIGHTBEARING CT is the coronal plane hindfoot component of the deformity, previously described as peritalar subluxation (PTS),29 where there is an external rotation, eversion, and abduction deformity of the foot underneath the talus through the triple joint complex. Multiple parameters associated with the severity of PTS were described and investigated in the literature. One very good

de Cesar Netto et al 3

example is the presence of sinus tarsi and subfibular impinge­ments. In a study of symptomatic PCFD patients with lateral hindfoot pain, Malicky et al24 demonstrated that WEIGHTBEARING CT reliably characterizes the presence of sinus tarsi impingement and subfibular impingement, which could potentially explain the presence of lateral symp­toms. They also reported a unique and important finding that all patients with subfibular impingement also had concurrent sinus tarsi impingement. The opposite findings, subfibular impingement in patients with sinus tarsi impingement, were not mandatory and much less frequent, providing an idea of chronology and that subfibular impingement could be a marker of more pronounced deformity. The authors finally concluded that the WEIGHTBEARING CT findings were consistent with lateral hindfoot pain in symptomatic PCFD and would correlate with indirect CR evidence of lateral impingement such as cysts and sclerosis in the sinus tarsi and subfibular areas.24 In a similar study comparing PCFD with and without lateral hindfoot pain, Ellis et al19 demonstrated that lateral hindfoot pain was associated with significant sub­talar joint degeneration, especially at the posterior facet. However, with closer independent evaluation of the presented images for posterior facet joint degeneration, it is easy to notice that rather than demonstrating intra­articular degenera­tion, the images show clear signs of extra­articular involve­ment, consistent with sinus tarsi impingement. The authors

also showed a trend toward increased frequency of subfibular impingement in PCFD patients, with good to excellent intra­ and interobserver reliability.19 The authors concluded empha­sizing the utility of WEIGHTBEARING CT in reliably assessing causes for lateral pain in PCFD patients.

Another WEIGHTBEARING CT parameter extensively investigated as a factor influencing the diagnosis and the sever­ity of PTS in PCFD patients is related to the subtalar joint anatomy. In a novel and landmark study by Colin et al,8 the investigators used WEIGHTBEARING CT to characterize the physiologic weightbearing morphology of the subtalar joint in asymptomatic individuals. They demonstrated that in the nor­mal anatomy of the posterior facet of the subtalar joint, the articular facet becomes progressively more angulated into a valgus position from anterior to posterior along its longitudinal length, when measured by the subtalar vertical angle (SVA—angle between the talar posterior facet of the subtalar joint and a vertical line perpendicular to the floor). The authors con­cluded that WEIGHTBEARING CT was an effective imaging modality for assessing the joint’s morphology, demonstrating a standard baseline threshold of normal anatomy, with implica­tions for surgical planning in reconstructive hindfoot surgery. Following that study, Apostle et al2 determined that symptom­atic PCFD patients demonstrated an increased innate valgus orientation of the posterior facet of the subtalar joint when assessed by the subtalar joint axis (STJA), which takes into

Figure 1. Most commonly used conventional radiographic measurements for the assessment of progressive collapsing foot deformity (PCFD) according to consensus votes from experts (total of 9 expert opinions), with percentage of votes. AP, anteroposterior; TMTJ, tarsometatarsal joint.

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consideration 2 landmarks within the talar bone (angulation between the talar posterior facet of the subtalar joint and the talar dome measured in coronal plane WEIGHTBEARING CT images). Subsequently, Probasco et al25 demonstrated that the alignment of the posterior facet of the subtalar joint could be reliably assessed on coronal WEIGHTBEARING CT using 2 angles: an angle between the inferior facet of the talus and the horizontal floor (inftal­hor), as well as an angle between infe­rior and superior facets of the talus (inftal­suptal), respectively similar to SVA and STJA. The authors found that when com­pared to controls, patients with PCFD had increased valgus inclination of the subtalar joint. While controls exhibited a varus orientation at the anterior aspect of the posterior facet, which progressively went into valgus at the central and poste­rior aspects of the joint, PCFD patients maintained a valgus orientation of the posterior facet throughout. A follow­up study by Cody et al7 demonstrated that not only do the inftal­hor and inftal­suptal angles show increased valgus orientation of the subtalar joint in PCFD patients, but more important, these WEIGHTBEARING CT angles significantly and positively correlate with multiple PCFD WEIGHTBEARING CR mea­surements, including TN coverage angle, talar–first metatarsal angle, calcaneal pitch, and medial column height. Specifically, the authors demonstrated that a inftal­suptal angle threshold of 17 degrees or more would significantly differentiate PCFD patients from controls, with this cutoff value of innate valgus angulation of the subtalar joint potentially representing an important risk factor for progressive deformity. In addition, this finding serves as a potential tool to guide treatment by identifying patients who could possibly benefit from early reconstructive surgery.

The severity of PTS in PCFD patients has also being inves­tigated by direct assessment of the overlap/subluxation of the articular facets using coronal plane WEIGHTBEARING CT images. In a landmark study by Ananthakrisnan et al,1 the authors demonstrated significantly decreased overlap in the anterior/middle and posterior facets of the subtalar joint when comparing PCFD and controls. The amount of subluxation was more pronounced in the anterior/middle facet than in the poste­rior facet. Following that study, the literature mostly focused on the severity of PTS measured at the posterior facet, with Ferri et al20 reporting the amount of lateral subluxation of the calca­neus at the posterior facet of the subtalar joint in millimeters. They found that only patients with PCFD demonstrated signifi­cant subluxation (26.6% of PCFD patients, with a mean dis­placement of 7 mm), with none of the control patients presenting with signs of PTS. More recently, de Cesar Netto et al14 empha­sized the role of the middle facet of the subtalar joint as possibly a more accurate indicator of PTS and symptomatic PCFD. The authors reported reliable assessment of PTS at the middle facet, showing that an incongruence angle greater than 8.4 degrees and a subluxation of more than 17.9% are highly accurate diag­nostic tools in symptomatic PCFD and potentially represent early findings of PCFD. The assessment of PTS in PCFD patients using the middle facet of the subtalar joint was also shown to demonstrate more severe deformity when compared

to the use of the posterior facet.18 Middle facet subluxation was found to be more pronounced than the subluxation of the poste­rior facet by an average of almost 18% in PCFD patients, sug­gesting that the middle facet may provide an earlier and more pronounced marker of progressive PTS in PCFD patients.

The use of WEIGHTBEARING CT semiautomatic multi­planar measurements has also been recently demonstrated to be a reliable and more complete isolated measurement to evaluate the 3­dimensional (3D) components of the PCFD.12,13 The use of the Foot and Ankle Offset (FAO),23 which measures the relationship between the position of the foot tripod (weightbearing points of the first and fifth meta­tarsal heads as well calcaneal tuberosity) in relation to the center of the ankle joint (most proximal and central point of the talar dome), was shown to be slightly more reliable than traditional manual PCFD measurements and to represent in a single measurement different components of the 3D defor­mity.13 More specifically, almost 80% of the changes in FAO measurements would be explained by variations in the hind­foot moment arm (HMA) (P < .00001), subtalar horizontal angle (P < .00001), talonavicular coverage angle (P = .00004), and forefoot arch angle (P = .0001).13 The same measurement was also shown to be a reliable and sensitive tool for assessment of preoperative PCFD as well as postop­erative correction, with patients demonstrating both signifi­cant improvement in FAO as well as patient­reported outcomes following PCFD reconstructive surgery.12 However, no direct correlation was found between postoper­ative improvements of FAO and patient­reported outcomes.

Given the combined results of these studies, the expert consensus opinion is to obtain WEIGHTBEARING CT images of the foot and ankle if available for surgical plan­ning prior to PCFD reconstruction, especially to assess early and pronounced findings of hindfoot deformity and PTS, including increased FAO, presence of sinus tarsi impinge­ment, subfibular impingement, increased valgus inclination of the posterior facet of the subtalar joint, and subluxation of the subtalar joint at the posterior and/or middle facet.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti­cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000­0001­ 6037­0685

Jonathan Day, MS, https://orcid.org/0000­0003­1106­3042

Scott J. Ellis, MD, https://orcid.org/0000­0002­4304­7445

Jeffrey E. Johnson, MD, https://orcid.org/0000­0003­2055­ 9998

de Cesar Netto et al 5

References

1. Ananthakrisnan D, Ching R, Tencer A, Hansen ST, Jr., Sangeorzan BJ. Subluxation of the talocalcaneal joint in adults who have symptomatic flatfoot. J Bone Joint Surg Am. 1999;81(8):1147­1154.

2. Apostle KL, Coleman NW, Sangeorzan BJ. Subtalar joint axis in patients with symptomatic peritalar subluxation compared to normal controls. Foot Ankle Int. 2014;35(11):1153­1158.

3. Arangio GA, Wasser T, Rogman A. Radiographic comparison of standing medial cuneiform arch height in adults with and without acquired flatfoot deformity. Foot Ankle Int. 2006;27(8):636­638.

4. Barg A, Amendola RL, Henninger HB, Kapron AL, Saltzman CL, Anderson AE. Influence of ankle position and radio­graphic projection angle on measurement of supramalleo­lar alignment on the anteroposterior and hindfoot alignment views. Foot Ankle Int. 2015;36(11):1352­1361.

5. Baverel L, Brilhault J, Odri G, Boissard M, Lintz F. Influence of lower limb rotation on hindfoot alignment using a conven­tional two­dimensional radiographic technique. Foot Ankle Surg. 2017;23(1):44­49.

6. Chadha H, Pomeroy G, Manoli A II. Radiologic signs of uni­lateral pes planus. Foot Ankle Int. 1997;18(9):603­604.

7. Cody EA, Williamson ER, Burket JC, Deland JT, Ellis SJ. Correlation of talar anatomy and subtalar joint alignment on weightbearing computed tomography with radiographic flat­foot parameters. Foot Ankle Int. 2016;37(8):874­881

8. Colin F, Horn Lang T, Zwicky L, Hintermann B, Knupp M. Subtalar joint configuration on weightbearing CT scan. Foot Ankle Int. 2014;35(10):1057­1062.

9. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal posi­tion of the heel following reconstruction of the stage II adult­acquired flatfoot deformity. Foot Ankle Int. 2015;36(8):919­927.

10. Conti MS, Garfinkel JH, Kunas GC, Deland JT, Ellis SJ. Postoperative medial cuneiform position correlation with patient­reported outcomes following cotton osteotomy for reconstruction of the stage II adult­acquired flatfoot defor­mity. Foot Ankle Int. 2019;40(5):491­498.

11. Dagneaux L, Moroney P, Maestro M. Reliability of hind­foot alignment measurements from standard radiographs using the methods of Meary and Saltzman. Foot Ankle Surg. 2019;25(2):237­241.

12. Day J, de Cesar Netto C, Nishikawa DRC, et al. Three­dimensional biometric weightbearing CT evaluation of the operative treatment of adult­acquired flatfoot deformity. Foot Ankle Int. 2020;41(8):930­936.

13. de Cesar Netto C, Bang K, Mansur NS, et al. Multiplanar semi­automatic assessment of foot and ankle offset in adult acquired flatfoot deformity. Foot Ankle Int. 2020;41(7):839­848.

14. de Cesar Netto C, Godoy­Santos AL, Saito GH, et al. Subluxation of the middle facet of the subtalar joint as a marker of peritalar subluxation in adult acquired flatfoot deformity: a case­control study. J Bone Joint Surg Am. 2019;101(20):1838­1844.

15. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible adult acquired flatfoot deformity: comparison between weight­bear­ing and non­weight­bearing measurements using cone­beam computed tomography. J Bone Joint Surg Am. 2017;99(18):e98.

16. de Cesar Netto C, Shakoor D, Dein EJ, et al. Influence of investigator experience on reliability of adult acquired flat­foot deformity measurements using weightbearing computed tomography. Foot Ankle Surg. 2019;25(4):495­502.

17. de Cesar Netto C, Shakoor D, Roberts L, et al. Hindfoot align­ment of adult acquired flatfoot deformity: a comparison of clinical assessment and weightbearing cone beam CT exami­nations. Foot Ankle Surg. 2019;25(6):790­797.

18. de Cesar Netto C, Silva T, Li S, et al. Assessment of posterior and middle facet subluxation of the subtalar joint in progres­sive flatfoot deformity [published online June 26, 2020]. Foot Ankle Int.

19. Ellis SJ, Deyer T, Williams BR, et al. Assessment of lat­eral hindfoot pain in acquired flatfoot deformity using weightbearing multiplanar imaging. Foot Ankle Int. 2010;31(5):361­371.

20. Ferri M, Scharfenberger AV, Goplen G, Daniels TR, Pearce D. Weightbearing CT scan of severe flexible pes planus deformities. Foot Ankle Int. 2008;29(2):199­204.

21. Haleem AM, Pavlov H, Bogner E, Sofka C, Deland JT, Ellis SJ. Comparison of deformity with respect to the talus in patients with posterior tibial tendon dysfunction and controls using multiplanar weight­bearing imaging or conventional radiography. J Bone Joint Surg Am. 2014;96(8):e63.

22. Kunas GC, Probasco W, Haleem AM, Burket JC, Williamson ERC, Ellis SJ. Evaluation of peritalar subluxation in adult acquired flatfoot deformity using computed tomography and weightbearing multiplanar imaging. Foot Ankle Surg. 2018;24(6):495­500.

23. Lintz F, Welck M, Bernasconi A, et al. 3D biometrics for hindfoot alignment using weightbearing CT. Foot Ankle Int. 2017;38(6):684­689.

24. Malicky ES, Crary JL, Houghton MJ, Agel J, Hansen ST Jr, Sangeorzan BJ. Talocalcaneal and subfibular impingement in symptomatic flatfoot in adults. J Bone Joint Surg Am. 2002;84(11):2005­2009.

25. Probasco W, Haleem AM, Yu J, Sangeorzan BJ, Deland JT, Ellis SJ. Assessment of coronal plane subtalar joint alignment in peritalar subluxation via weight­bearing multiplanar imag­ing. Foot Ankle Int. 2015;36(3):302­309.

26. Saltzman CL, Brandser EA, Berbaum KS, et al. Reliability of standard foot radiographic measurements. Foot Ankle Int. 1994;15(12):661­665.

27. Sangeorzan BJ, Mosca V, Hansen ST Jr. Effect of calcaneal lengthening on relationships among the hindfoot, midfoot, and forefoot. Foot Ankle. 1993;14(3):136­141.

28. Sensiba PR, Coffey MJ, Williams NE, Mariscalco M, Laughlin RT. Inter­ and intraobserver reliability in the radio­graphic evaluation of adult flatfoot deformity. Foot Ankle Int. 2010;31(2):141­145.

29. Toolan BC, Sangeorzan BJ, Hansen ST Jr. Complex recon­struction for the treatment of dorsolateral peritalar sublux­ation of the foot: early results after distraction arthrodesis of the calcaneocuboid joint in conjunction with stabilization of, and transfer of the flexor digitorum longus tendon to, the mid­foot to treat acquired pes planovalgus in adults. J Bone Joint Surg Am. 1999;81(11):1545­1560.

30. Younger AS, Sawatzky B, Dryden P. Radiographic assess­ment of adult flatfoot. Foot Ankle Int. 2005;26(10):820­825.

31. Zhang Y, Xu J, Wang X, et al. An in vivo study of hindfoot 3D kinetics in stage II posterior tibial tendon dysfunction (PTTD) flatfoot based on weight­bearing CT scan. Bone Joint Res. 2013;2(12):255­263.

https://doi.org/10.1177/1071100720950738

Foot & Ankle International® 1 –4© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950738journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted

1. CONSENSUS STATEMENT—Subtalar joint fusion should be considered in the treatment of deformities where the subtalar joint is arthritic and stiff or where there is severe peritalar subluxation/dislocation (subtalar joint subluxation/dislocation, subfibular impingement).

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%

(Unanimous, Strongest Consensus)2. CONSENSUS STATEMENT—In the correction of

the forefoot varus component of progressive collaps-ing foot deformity (PCFD), naviculocuneiform (NC) joint fusion should be considered when the NC joint is arthritic and symptomatic and/or when there is sig-nificant sagittal plane sagging of the NC joint.

950738 FAIXXX10.1177/1071100720950738Foot & Ankle InternationalHintermann et alresearch-article2020

1Kantonspital Baselland, Liestal, Switzerland2Hospital for Special Surgery, New York, NY, USA3Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA4Washington University School of Medicine, St. Louis, MO, USA5Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA6University of Washington, Seattle, WA, USA7Cedars-Sinai Medical Center, Los Angeles, CA, USA8Mercy Medical Center, Baltimore, MD, USA9New York University Grossman School of Medicine, New York, NY, USA10Johns Hopkins School of Medicine, Baltimore, MD, USA 11Georgetown School of Medicine, Washington, DC, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Consensus on Indications for Isolated Subtalar Joint Fusion and Naviculocuneiform Fusions for Progressive Collapsing Foot Deformity

Beat Hintermann, MD1, Jonathan T. Deland, MD2, Cesar de Cesar Netto, MD, PhD3 , Scott J. Ellis, MD2 , Jeffrey E. Johnson, MD4 , Mark S. Myerson, MD5, Bruce J. Sangeorzan, MD6, David Thordarson, MD7, and Lew C. Schon, MD8,9,10,11

AbstractRecommendation: Peritalar subluxation represents an important hindfoot component of progressive collapsing foot deformity, which can be associated with a breakdown of the medial longitudinal arch. It results in a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and pronation. Loss of peritalar stability allows the talus to rotate and translate on the calcaneal and navicular bone surfaces, typically moving medially and anteriorly, which may result in sinus tarsi and subfibular impingement. The onset of degenerative disease can manifest with stiffening of the subtalar (ST) joint and subsequent fixed and possibly arthritic deformity. While ST joint fusion may permit repositioning and stabilization of the talus on top of the calcaneus, it may not fully correct forefoot abduction and it does not correct forefoot varus. Such varus may be addressed by a talonavicular (TN) fusion or a plantar flexion osteotomy of the first ray, but, if too pronounced, it may be more effectively corrected with a naviculocuneiform (NC) fusion. The NC joint has a curvature in the sagittal plane. Thus, preserving the shape of the joint is the key to permitting plantarflexion correction by rotating the midfoot along the debrided surfaces and to fix it. Intraoperatively, care must be also taken to not overcorrect the talocalcaneal angle in the horizontal plane during the ST fusion (eg, to exceed the external rotation of the talus and inadvertently put the midfoot in a supinated position). Such overcorrection can lead to lateral column overload with persistent lateral midfoot pain and discomfort. A contraindication for an isolated ST fusion may be a rupture of posterior tibial tendon because of the resultant loss of the internal rotation force at the TN joint. In these cases, a flexor digitorum longus tendon transfer is added to the procedure.Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, peritalar instability, subtalar fusion, naviculocuneiform fusion, subfibular impingement, progressive collapsing foot deformity, PCFD

2 Foot & Ankle International 00(0)

Delegate Vote: Agree: 89% (8/9), Disagree: 0%; Abstain 11% (1/9)(Strong Consensus)

Rationale

Subtalar (ST) fusion has been used in PCFD surgery in advanced stages of deformity, mostly including the talona-vicular (TN) and the calcaneocuboid (CC) joints (eg, triple arthrodesis).12,21,23,24,32 More recently, to preserve motion in the lateral column, double arthrodesis has been advo-cated for the operative treatment of more advanced stages of PCFD.4,26,31,38 The rationale in both the triple and dou-ble fusion is that the ST fusion provides hindfoot correc-tion and stability, whereas the TN fusion corrects the forefoot supination and abduction. However, there is little evidence in the literature whether TN fusion does suffi-ciently address the breakdown of the medial arch and the forefoot supination associated with hindfoot peritalar sub-luxation (PTS) in PCFD. In cadaveric studies, a double arthrodesis (ST and TN fusion) was able to fully correct the deformity, but no indications were made regarding res-toration of the medial arch.29 By assessing the dynamic plantar pressure distribution in 16 feet after ST and TN fusion, force transmission of the midfoot was increased, whereas push-off force was decreased, as compared with healthy feet.33 Apparently, a fusion at the TN joint in addi-tion to ST fusion may work if the main pathology is PTS, but it may have a limited effect on restoration of the medial longitudinal arch and forefoot pronation when the defor-mity is mainly caused by collapse of the medial column structures of the midfoot associated with PTS. With stiff-ening of the hindfoot, the breakdown of medial arch may even increase as a result of subsequent overload due to stress transfer to the adjacent nonfused joints. Theoretically, an extension of the ST and TN fusion to the naviculocu-neiform (NC) joint may be the solution to correct the over-all deformity.2 However, extensive surgical exposure is required, and debridement of navicular bone carries with it fear of devascularization. Fixation is also very challenging for this rather small joint.

In PCFD, a controversial concept is the notion that its origin of the deformity can be distal to the hindfoot joints due to breakdown of the medial longitudinal arch.14 Posterior tibial tendon (PTT) function may be preserved or not. Therefore, a careful clinical evaluation with appropri-ate history and physical exam is an important starting point. Clinically, the visible severity of flattening of the medial longitudinal arch and the forefoot abduction in combination with hindfoot valgus are hallmarks of this disorder.10 The diagnosis can further be confirmed by the first-ray raise sign when the hindfoot pronation and valgus position are passively corrected.16 While in most instances, the medial longitudinal arch can easily be corrected manually if the

foot is unloaded, the valgus and pronation deformity of the hindfoot may be or may be not correctable.

In general, while the severity of the deformity and amount of breakdown of the medial arch are evident on clinical exam, most surgeons use radiographic parameters to help guide their decision making. Many different radio-graphic measures have been described.39 The consensus of our group was that the talar–first metatarsal angle, in both lateral and anteroposterior (AP) views, and the talonavicu-lar uncoverage angle on an AP view of the foot are most helpful. Other measures of a PCFD that have been discussed regarding the necessity for reconstruction of the medial arch include the AP lateral incongruency angle15,37,39 and the talocalcaneal overlap on lateral WEIGHTBEARING radiographs of the foot.3 The lateral view also serves for assessing the degree of sagging of the TN, NC, and first tarsometatarsal (TMT) joints, which may have an impact regarding the necessity and the location of medial column stabilization and ST fusion procedures. While the Saltzman axial heel views and ankle radiographs are important for fully assessing PCFD, they do not influence the decision to perform a ST and NC fusion.

With the introduction of WEIGHTBEARING computed tomography (WBCT) scans, a more detailed analysis of the subtalar joint and hindfoot positioning during loading has become possible, and thus it has a significant role in evalu-ating PCFD, especially with respect to decision making for a ST fusion. An increased subluxation among the patients with PCFD of 56% was reported vs 13% among the con-trols at the anterior and middle facets and 30% vs 11% at the posterior facet.1 Currently, the middle facet is used as an isolated marker for PTS, with a mean subluxation (uncover-age) of approximately 45% in symptomatic patients with PCFD and 5% among controls.8 Measurement of the amount of linear subluxation of the subtalar joint at the posterior facet in the coronal plane has also been proposed to indicate PTS,7,9,30 but it was found to be less reliable.9 Lateral sub-luxation was reported to cause sinus tarsi and subfibular impingement.27 The consensus of our group was that PCFD patients with severe PTS (marked subtalar joint subluxation and subfibular impingement) should be considered for ST fusion. Pain secondary to degenerative disease and stiffness at the subtalar joint are also an indication for ST fusion. There is a consensus of our group that there is need for a ST fusion as the primary measure to address severe PTS as well as rigid/arthritic subtalar joints.

Isolated ST repositional arthrodesis for moderate to severe PCFD was found to produce excellent correction of the hindfoot.22,25,36 It is generally accepted that, with an incompetent medial arch, an additional medial column sta-bilizing procedure will be necessary to address the com-plex deformity.2,3,16,35 To date, most surgeons rely on fusion at the TN site or even include the CC joint in the belief that this is mandatory for correction of significant

Hintermann et al 3

forefoot abduction and uncoverage of the talar head. However, the concept of using an NC fusion instead TN fusion was reported to be successful in correcting and sta-bilizing the forefoot.34,35 With the hypothesis that attenua-tion of the medial supporting structures of the foot results in the progression of the PCFD, Miller28 was the first to propose correction of the medial alignment of the foot by fusion of the medial column, specifically, a fusion of the NC and first TMT joints. In addition to the medial column fusion, he performed an advancement of the PTT complex as an osteoperiosteal flap. His theory that progression of PCFD results from extreme flexibility of the midtarsal joints was supported by others,5,6,11,17,20 all of whom have used an NC fusion as the key procedure. Although the above procedures were described primarily for use in the pediatric or adolescent flatfoot, similar principles can be used in PCFD.

While many studies have been published on the surgical management of PCFD, almost all of them appropriately report on combinations of procedures used to correct this complex deformity. This feature of the PCFD literature makes it difficult to separate the contributions of the various components of each surgery to the final outcome. However, the literature does provide evidence that the best results are achieved when the deformity is fully corrected.18,19 Although the literature is still sparse, the concept of adding an NC fusion to the ST fusion has apparently the capability to correct and stabilize the complex deformity in advanced stages of PCFD in both the flexible or fixed condi-tion.5,11,17,20,28 Thus, there was a consensus of our group that NC joint fusion should be considered in the arthritic and symptomatic joints, as well as when significant sagittal plane sagging of the NC joints is present.

Because PTS results in greater subluxation in the ante-rior than in the posterior ST joint,1 a medial approach to the ST joint makes it easier and more effective for the sur-geon to reposition the talus on the top of calcaneus.2,13 It also allows for the tightening of the medial capsule and deltoid ligament complex and to debride and/or tighten the PTT or, if incompetent, to do a flexor digitorum longus (FDL) tendon transfer. Two to 3 screws are usually neces-sary to provide the stability needed at the ST fusion site against translational and rotational forces.13 While pre-serving the TN joint with its capsule, the NC joint can be exposed by lengthening the medial incision distally. The NC joint can be distracted over 2 K-wires, and after debridement to subchondral bone, the K-wires can be used as joysticks to plantarflex the first ray and to apply com-pression force at the fusion site.13 Beside screw fixation, a medioplantar tension band plate can ensure optimal stabil-ity.2,13 Even though prior literature has reported important nonunion rates of NC joint fusions,20,28,34 using this

surgical technique, union of both joints was found in 32 of 34 cases; a nonunion occurred in only 1 case at the ST joint and in 1 case at the NC fusion site, but the patient remained asymptomatic.35 The low nonunion rate could potentially be explained by a protective effect of the ST fusion stability to the fusion site at the NC joint, possibly decreasing the mechanical overload in this joint, even with early weightbearing as tolerated being allowed immedi-ately postoperatively. In 15 cases (44%), an additional medial sliding osteotomy of the calcaneus was performed to achieve the required correction of hindfoot alignment, and in 5 cases (14.7%), an FDL tendon transfer was done. Radiographically, all angles of interest were found to be corrected significantly, and there was no loss of correction observed after 2 years.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

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2. Barg A, Brunner S, Zwicky L, Hintermann B. Subtalar and naviculocuneiform fusion for extended breakdown of the medial arch. Foot Ankle Clin. 2011;16(1):69-81.

3. Benink RJ. The constraint-mechanism of the human tarsus: a roentgenological experimental study. Acta Orthop Scand Suppl. 1985;215:1-135.

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7. Cody EA, Williamson ER, Burket JC, Deland JT, Ellis SJ. Correlation of talar anatomy and subtalar joint alignment on

4 Foot & Ankle International 00(0)

weightbearing computed tomography with radiographic flat-foot parameters. Foot Ankle Int. 2016;37(8):874-881.

8. de Cesar Netto C, Godoy-Santos AL, Saito GH, et al. Subluxation of the middle facet of the subtalar joint as a marker of peritalar subluxation in adult acquired flatfoot deformity: a case-control study. J Bone Joint Surg Am. 2019;101(20):1838-1844.

9. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible adult acquired flatfoot deformity: comparison between weight-bearing and non-weight-bearing measurements using cone-beam computed tomography. J Bone Joint Surg Am. 2017;99(18):e98.

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23. Kadakia AR, Haddad SL. Hindfoot arthrodesis for the adult acquired flat foot. Foot Ankle Clin. 2003;8(3):569-594, x.

24. Kelly IP, Easley ME. Treatment of stage 3 adult acquired flatfoot. Foot Ankle Clin. 2001;6(1):153-166.

25. Kitaoka HB, Patzer GL. Subtalar arthrodesis for posterior tibial tendon dysfunction and pes planus. Clin Orthop Relat Res. 1997;345:187-194.

26. Knupp M, Schuh R, Stufkens SA, Bolliger L, Hintermann B. Subtalar and talonavicular arthrodesis through a single medial approach for the correction of severe planovalgus deformity. J Bone Joint Surg Br. 2009;91(5):612-625.

27. Malicky ES, Crary JL, Houghton MJ, Agel J, Hansen ST Jr, Sangeorzan BJ. Talocalcaneal and subfibular impingement in symptomatic flatfoot in adults. J Bone Joint Surg Am. 2002;84(11):2005-2009.

28. Miller OL. A plastic flat foot operation. J Bone Joint Surg. 1927;9(1):84-91.

29. O’Malley MJ, Deland JT, Lee KT. Selective hindfoot arthrod-esis for the treatment of adult acquired flatfoot deformity: an in vitro study. Foot Ankle Int. 1995;16(7):411-417.

30. Probasco W, Haleem AM, Yu J, Sangeorzan BJ, Deland JT, Ellis SJ. Assessment of coronal plane subtalar joint alignment in peritalar subluxation via weight-bearing multiplanar imag-ing. Foot Ankle Int. 2015;36(3):302-309.

31. Rohm J, Zwicky L, Horn Lang T, Salentiny Y, Hintermann B, Knupp M. Mid- to long-term outcome of 96 corrective hindfoot fusions in 84 patients with rigid flatfoot deformity. Bone Joint J. 2015;97B(5):668-674.

32. Sangeorzan BJ, Smith D, Veith R, Hansen ST Jr. Triple arthrodesis using internal fixation in treatment of adult foot disorders. Clin Orthop Relat Res. 1993;294:299-307.

33. Schuh R, Salzberger F, Wanivenhaus AH, Funovics PT, Windhager R, Trnka HJ. Kinematic changes in patients with double arthrodesis of the hindfoot for realignment of pla-novalgus deformity. J Orthop Res. 2013;31(4):517-524.

34. Seymour N. The late results of naviculo-cuneiform fusion. J Bone Joint Surg Br. 1967;49(3):558-559.

35. Steiner CS, Gilgen A, Zwicky L, Schweizer C, Ruiz R, Hintermann B. Combined subtalar and naviculocuneiform fusion for treating adult acquired flatfoot deformity with medial arch collapse at the level of the naviculocuneiform joint. Foot Ankle Int. 2019;40(1):42-47.

36. Stephens HM, Walling AK, Solmen JD, Tankson CJ. Subtalar repositional arthrodesis for adult acquired flatfoot. Clin Orthop Relat Res. 1999;365:69-73.

37. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of the adult acquired flatfoot deformity. Curr Rev Musculoskelet Med. 2013;6(4):294-303.

38. Wachter JD, Knupp M, Beat H. Double-hindfoot arthrodesis through a single medial approach. Techn Foot Ankle Surg. 2007;6(4):237-242.

39. Younger AS, Sawatzky B, Dryden P. Radiographic assess-ment of adult flatfoot. Foot Ankle Int. 2005;26(10):820-825.

https://doi.org/10.1177/1071100720950739

Foot & Ankle International® 1 –3© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950739journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted:

CONSENSUS STATEMENT ONE: A stable medial longitudinal column is critical for restoration of a bal-anced foot tripod.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT TWO: Indications for per-forming a Cotton osteotomy for residual forefoot varus should be determined clinically, not radiographically, after hindfoot deformity correction. By pushing up on the bot-tom of the forefoot, the surgeon can feel the head of the first metatarsal in relation to the fifth metatarsal head. This maneuver will indicate if correction is needed and help determine when adequate correction has been obtained.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT THREE: The typical wedge size needed for correction using a medial cunei-form dorsal opening wedge (Cotton) osteotomy ranges from 5 to 11 mm.

Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)

950739 FAIXXX10.1177/1071100720950739Foot & Ankle InternationalJohnson et alresearch-article2020

1Washington University School of Medicine, St. Louis, MO, USA2University of Washington, Seattle, WA, USA3University of Iowa, Department of Orthopaedics and Rehabilitation, Iowa City, IA, USA4Hospital for Special Surgery, New York, NY, USA5Kantonspital Baselland, Liestal, Switzerland6Mercy Medical Center, Baltimore, MD, USA7New York University Grossman School of Medicine, New York, NY, USA8Johns Hopkins School of Medicine, Baltimore, MD, USA 9Georgetown School of Medicine, Washington, DC, USA10Cedars-Sinai Medical Center, Los Angeles, CA, USA11Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Consensus on Indications for Medial Cuneiform Opening Wedge (Cotton) Osteotomy in the Treatment of Progressive Collapsing Foot Deformity

Jeffrey E. Johnson, MD1 , Bruce J. Sangeorzan, MD2, Cesar de Cesar Netto, MD, PhD3 , Jonathan T. Deland, MD4, Scott J. Ellis, MD4 , Beat Hintermann, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, and Mark S. Myerson, MD11

AbstractRecommendation: Forefoot varus is a physical and radiographic examination finding associated with the Progressive Collapsing Foot Deformity (PCFD). Varus position of the forefoot relative to the hindfoot is caused by medial midfoot collapse with apex plantar angulation of the medial column. Some surgeons use the term forefoot supination to describe this same deformity (see Introduction section with nomenclature). Correction of this deformity is important to restore the weightbearing tripod of the foot and help resist a recurrence of foot collapse. When the forefoot varus deformity is isolated to the medial metatarsal and medial cuneiform, correction is indicated with an opening wedge medial cuneiform (Cotton) osteotomy, typically with interposition of an allograft bone wedge from 5 to 11 mm in width at the base. When the forefoot varus is global, involving varus angulation of the entire forefoot and midfoot relative to the hindfoot, other procedures are needed to adequately correct the deformity.Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, forefoot varus, Cotton osteotomy, cuneiform osteotomy, progressive collapsing foot deformity, PCFD

2 Foot & Ankle International 00(0)

CONSENSUS STATEMENT FOUR: Presence of some clinical instability of the first ray does not preclude the use of a Cotton osteotomy.Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, 11% (1/9).CONSENSUS STATEMENT FIVE: The presence of gross clinical instability of the first ray and/or radio-graphic plantar gapping of the first tarsometatarsal joint are indications for first tarsometatarsal joint fusion.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.

Rationale

Forefoot varus is a component of the multiplanar Progressive Collapsing Foot Deformity (PCFD), as well as in some cases of developmental pes planovalgus and osteoarthritis of the medial column of the foot. This deformity is not cor-rected by hindfoot procedures such as a lateral column lengthening, medial displacement calcaneal osteotomy, or repositional subtalar arthrodesis.

Forefoot varus is characterized by a spectrum of physical examination findings from elevation of the first ray (only in the sagittal plane) or rotation of the entire forefoot around the central longitudinal axis of the foot toward the midline in the coronal plane with deformity at the talonavicular joint, mid-tarsal joints, or tarsometatarsal joints. The deformity may be fixed or flexible and the diagnosis is made by physical exami-nation in the nonweightbearing position, with the hindfoot corrected to a neutral hindfoot alignment reference position. This examination will indicate the location, magnitude, and flexibility of the deformity as well as indicate when the defor-mity has been adequately corrected intraoperatively. First-ray elevation is typically related to dorsal instability of the first tarsometatarsal (TMT) or first-second intercuneiform joint with dorsal angulation at the naviculocuneiform joint.

A lateral weightbearing radiograph will help determine the presence of dorsal instability, plantar first TMT joint gapping, osteoarthritis, as well as location of the apex of the deformity along the medial column as being at the talonavicular, navicu-locuneiform, or TMT joints.6,12 Reconstruction of the PCFD begins in the proximal aspect of the foot and ankle and pro-ceeds distally because each level of correction is determined by aligning it to the next most proximal segment. Therefore, forefoot varus is often the last portion of the deformity to be corrected during the bony realignment portion of the proce-dure. Occasionally, once the hindfoot deformity correction has been performed, the apparent forefoot varus that was present preoperatively has been improved sufficiently that osteotomy of the medial cuneiform is not required.

Correction of this deformity with an opening wedge, plantarflexion, medial cuneiform osteotomy was described by Cotton in 1936 to restore the “static triangle of support.”4 However, the Cotton osteotomy did not gain widespread use until decades later, when surgeons began using

joint-preserving osteotomies, especially lateral column lengthening (LCL) procedures, and noted that residual fore-foot varus was limiting the complete correction of many feet with PCFD.5 Currently, osteotomy of the medial cunei-form is a commonly used technique to correct forefoot varus, with the concept that restoring the weightbearing tri-pod of the foot will help resist recurrent foot collapse. Benthien et al, in a cadaveric biomechanical study, demon-strated that LCL increased lateral forefoot pressures in a severe PCFD model.2 The authors demonstrated that an added Cotton osteotomy provided increased deformity cor-rection and decreased pressure under the lateral forefoot, thereby suggesting that the Cotton osteotomy could help restore a more normal loading pattern of the foot.

Alternative Technique

A closing wedge osteotomy for correction of forefoot varus performed from a plantar approach to the medial cuneiform has been described and has the advantage of direct bone heal-ing without a need for graft, no implant interposition, ability to perform the procedure through a single plantar incision used for the medial soft tissue repair, and the ability to slightly adduct the foot through the osteotomy.10 However, the amount of correction is more difficult to titrate for a given deformity, and closing a significant wedge resection to achieve apposition of the cuneiform can be challenging.

Multiple fixation techniques for Cotton osteotomies have been described, using specialized wedge plates, screws,5,11 Kirschner wires,11 and no fixation.3,11,15 Alternatives to allograft or autografting methods include use of trabecular metal wedges,13,14 or metal wedges attached to thin dorsal plates. A dorsal wedge plate has been found to be as effective as a bone graft wedge in a cadaver model.9 Potential advan-tages include no donor site morbidity seen with autograft, no potential risk of disease transmission with allograft and eas-ier availability for outpatient surgical centers. In a series of patients that received trabecular metal wedges, 2 nonunions were identified, but only 1 was found to be symptomatic at 35.4 months postoperation.14

The disadvantage of plates and screws is that they may cre-ate a painful prominence on the dorsum of the foot requiring an additional surgical procedure for hardware removal,5,11,15 and metal wedges may confound any future revision surgery. The metallic wedges need to be removed with a saw if revi-sion of the osteotomy is needed and they are difficult to drill across or place a screw through them if an extended medial column fusion is required later. Long-term studies evaluating the durability of these nonbiologic implants are lacking.

Extraosseous and intraosseous blood supply to the medial cuneiform is robust and does not exhibit consistent watershed areas of hypovascularity.7 Predictable osteotomy healing rates using allograft wedges, of up to a 100%, has been reported by many authors, and they do not seem to be related to type of fixation or whether any fixation is utilized.1,3,5,11,15

Johnson et al 3

Quantifying the contribution of the Cotton osteotomy to the overall radiographic changes from preoperative to post-operative is difficult given that multiple procedures are usu-ally preformed at the time of surgery. Numerous radiographic measurements have been used to describe the correction that is observed following Cotton osteotomy including the lateral talus-first metatarsal angle, lateral medial cuneiform metatarsal angle, calcaneal pitch, medial cuneiform dis-tance,5 medial arch sag angle (MASA),1 and cuneiform articular angle (CAA).3 Using a multivariate linear regres-sion model, Kunas et al demonstrated that the Cotton oste-otomy graft size was significantly associated with changes in the CAA, calcaneal pitch, lateral talonavicular Cobb angle, and lateral naviculomedial cuneiform angle.8 However, the authors emphasized that the Cotton graft size was the only factor found to significantly predict a change in the CAA. Therefore, preoperative measurement of the cuneiform articular angle (CAA) can help predict the graft size intraoperatively. Each millimeter of the width of the base of the wedge-shaped graft corresponds to an approxi-mately 2.1-degree decrease of the CAA.8 However, intraop-erative clinical examination is best used to confirm the proper graft size that provides satisfactory correction of the deformity. Typically, a graft size of 5-11 mm width at the base of the wedge is needed to correct most deformities.

The indication for performing a Cotton osteotomy should be determined clinically, not radiographically, and is depen-dent on the presence of residual forefoot varus after hind-foot deformity correction.6,12 By pushing up on the bottom of the forefoot, the surgeon can feel the balance of the first ray in relation to the lateral rays by placing one thumb of each hand on the first and fifth metatarsal heads, respec-tively. This maneuver will indicate which metatarsals are elevated relative to the fifth metatarsal and help determine whether a Cotton osteotomy, alone, is indicated or whether a more global correction of the midfoot is needed.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

References

1. Aiyer A, Dall GF, Shub J, Myerson MS. Radiographic cor-rection following reconstruction of adult acquired flat foot deformity using the cotton medial cuneiform osteotomy. Foot Ankle Int. 2016;37(5):508-513.

2. Benthien RA, Parks BG, Guyton GP, Schon LC. Lateral column calcaneal lengthening, flexor digitorum longus transfer, and opening wedge medial cuneiform osteotomy for flexible flatfoot: a biomechanical study. Foot Ankle Int. 2007;28(1):70-77.

3. Castaneda D, Thordarson DB, Charlton TP. Radiographic assessment of medial cuneiform opening wedge osteotomy for flatfoot correction. Foot Ankle Int. 2012;33(6):498-500.

4. Cotton FJ. Foot statics and surgery. N Engl J Med. 1936;214(8):353-362.

5. Hirose CB, Johnson JE. Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed fore-foot varus associated with flatfoot deformity. Foot Ankle Int. 2004;25(8):568-574.

6. Johnson JE, Yu JR. Arthrodesis techniques in the manage-ment of stage II and III acquired adult flatfoot deformity. Instr Course Lect. 2006;55:531-542.

7. Kraus JC, McKeon KE, Johnson JE, McCormick JJ, Klein SE. Intraosseous and extraosseous blood supply to the medial cuneiform: implications for dorsal opening wedge plan-tarflexion osteotomy. Foot Ankle Int. 2014;35(4):394-400.

8. Kunas GC, Do HT, Aiyer A, Deland JT, Ellis SJ. Contribution of medial cuneiform osteotomy to correction of longitudinal arch collapse in stage IIb adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(8):885-893.

9. League AC, Parks BG, Schon LC. Radiographic and pedobarographic comparison of femoral head allograft versus block plate with dorsal opening wedge medial cunei-form osteotomy: a biomechanical study. Foot Ankle Int. 2008;29(9):922-926.

10. Ling JS, Ross KA, Hannon CP, et al. A plantar closing wedge osteotomy of the medial cuneiform for residual fore-foot supination in flatfoot reconstruction. Foot Ankle Int. 2013;34(9):1221-1226.

11. Lutz M, Myerson M. Radiographic analysis of an opening wedge osteotomy of the medial cuneiform. Foot Ankle Int. 2011;32(3):278-287.

12. McCormick JJ, Johnson JE. Medial column procedures in the correction of adult acquired flatfoot deformity. Foot Ankle Clin. 2012;17(2):283-298.

13. Romeo G, Bianchi A, Cerbone V, Parrini MM, Malerba F, Martinelli N. Medial cuneiform opening wedge osteotomy for correction of flexible flatfoot deformity: trabecular titanium vs. bone allograft wedges. Biomed Res Int. 2019;2019:1472471.

14. Tsai J, McDonald E, Sutton R, Raikin SM. Severe flexible pes planovalgus deformity correction using trabecular metal-lic wedges. Foot Ankle Int. 2019;40(4):402-407.

15. Wang CS, Tzeng YH, Lin CC, Chang MC, Chiang CC. Comparison of screw fixation versus non-fixation in dorsal opening wedge medial cuneiform osteotomy of adult acquired flatfoot. Foot Ankle Surg. 2020;26(2):193-197.

https://doi.org/10.1177/1071100720950741

Foot & Ankle International® 1 –4© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950741journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted:

CONSENSUS STATEMENT ONE: We recommend performing a medializing calcaneal displacement osteot-omy (MDCO) as isolated bony procedure when there is an isolated hindfoot valgus, with adequate talonavicular joint coverage (less than 35%-40% uncoverage), and lack of significant forefoot supination, varus, or abduction.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT TWO: The typical range when performing a MDCO, while considering the loca-tion and rotation of the osteotomy, is 7 to 15 mm of correction.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT THREE: Lateral col-umn lengthening (LCL) procedure is recommended when the amount of talonavicular joint uncoverage is above 40%. The amount of coverage needed should be judged intraoperatively by the amount of correction of the uncoverage and by adequate residual passive ever-sion range of motion of the subtalar joint.Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9).(Strong consensus)

CONSENSUS STATEMENT FOUR: The typical range when performing a lateral column lengthening is 5 to 10 mm of correction.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATETMENT FIVE: Indications for performing a cotton osteotomy should be determined clinically, not radiographically, related to residual fore-foot supination after hindfoot deformity correction. Feel the balance of first ray in relation to the lateral ones, pal-pating the plantar aspect of the metatarsal heads.

950741 FAIXXX10.1177/1071100720950741Foot & Ankle InternationalEllis et alresearch-article2020

1Hospital for Special Surgery, New York, NY, USA2Washington University School of Medicine, St. Louis, MO, USA3Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA4Kantonspital Baselland, Liestal, Switzerland5Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA6Mercy Medical Center, Baltimore, MD, USA7New York University Grossman School of Medicine, New York, NY, USA 8Johns Hopkins School of Medicine, Baltimore, MD, USA9Georgetown School of Medicine, Washington, DC, USA10Cedars-Sinai Medical Center, Los Angeles, CA, USA11University of Washington, Seattle, WA, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Titrating the Amount of Bony Correction in Progressive Collapsing Foot Deformity

Scott J. Ellis, MD1 , Jeffrey E. Johnson, MD2 , Jonathan Day, MS1 , Cesar de Cesar Netto, MD, PhD3 , Jonathan T. Deland, MD1, Beat Hintermann, MD4, Mark S. Myerson, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, Bruce J. Sangeorzan, MD11

AbstractRecommendation: There is evidence indicating that the amount of bony correction performed in the setting of progressive collapsing foot deformity reconstructive surgery can be titrated within a recommended range for a variety of procedures. The typical range when performing a medial displacement calcaneal osteotomy should be 7 to 15 mm of medialization of the tuberosity. The typical range when performing an Evans lateral column lengthening should be 5 to 10 mm of a laterally based wedge in the anterior calcaneus. The typical range when performing a plantarflexion opening wedge osteotomy of the medial cuneiform (Cotton) osteotomy should be 5 to 10 mm of a dorsal wedge.Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, adult acquired flatfoot deformity, AAFD, reconstruction, osteotomy, titration, progressive collapsing foot deformity, PCFD

2 Foot & Ankle International 00(0)

Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATETMENT SIX: We report a typi-cal range of 5 to 11 mm opening dorsal wedges of the medial cuneiform (Cotton) to be used for correction.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATETMENT SEVEN: Presence of some clinical instability of the first ray does not preclude the use of Cotton osteotomies.Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, 11% (1/9).(Strong consensus)

Rationale

The purpose of bony procedures such as the medial dis-placement calcaneal osteotomy (MDCO), lateral column lengthening (LCL), and Cotton osteotomy is to correct symptomatic progressive collapsing foot deformity (PCFD) by restoring normal alignment and the medial longitudinal arch. To date, there has been no general consensus regard-ing a recommended range of correction for such bony pro-cedures, nor has there been a general consensus on methods to titrate them. Such guidelines are essential to help achieve optimal operative correction and theoretically maximize patient-reported outcomes.

MDCO is commonly performed to correct the valgus hindfoot, with studies highlighting its efficacy as the most significant contributor to hindfoot alignment correction.4 Using the validated hindfoot moment arm (HMA) mea-surement on the hindfoot alignment view,23 Chan et al derived a linear equation relating the change in preopera-tive and postoperative HMA with the amount of MDCO correction, demonstrating that a medial translation of 1 mm corresponds to approximately 1.5 mm change in radio-graphic HMA.4 This aids in preoperative titration of the amount of MDCO needed in order to correct the hindfoot valgus deformity and achieve a clinically straight heel (ie, physiologically valgus hindfoot). A study by Conti et al compared postoperative outcomes in 3 groups of patients based on postoperative HMA: those with residual valgus alignment, mild varus overcorrection of 0 to 5 mm, and moderate varus overcorrection of greater than 5 mm.7 The authors not only determined that mild radiographic over-correction of 0 to 5 mm resulted in a clinically straight heel, but also that this range of correction was associated with superior patient-reported outcomes.7 In both afore-mentioned studies, the amount of MDCO performed varied between patients based on severity of the deformity, with Chan et al noting that the mean amount of MDCO correc-tion was 10.4 mm (SD 1.9).4 Although previous studies in the literature have attempted to provide specific amounts

of correction of approximately 10 mm,1,11,12,20,21 the use of a recommended range is more appropriate given the vary-ing degrees of preoperative hindfoot valgus alignment is more appropriate. Given the results of these studies and the end goal of achieving a clinically straight heel, the expert consensus is that the typical range of MDCO performed is 7 to 15 mm of correction.

LCL with either an Evans-type,16 Central (Hintermann),13 or Van der Griend (step-cut)26 osteotomy is commonly used to correct forefoot and midfoot abduc-tion at the talonavicular (TN) joint, which can be evalu-ated using the lateral incongruency angle, TN coverage angle, and talo–first metatarsal angle on anteroposterior radiograph.12,24,27 Because LCL is a powerful procedure in correcting abduction and there is a risk for overcorrection, studies have cited a TN uncoverage of greater than 40% as an indication for LCL.9,24 Previous work has also derived a linear equation relating the change in lateral incongru-ency angle (LIA) with the amount of LCL correction,3 which allows for preoperative planning and titration of operative correction.6 Proper titration and correction are integral to the success of the procedure as multiple studies have shown that overcorrection (adduction of the TN joint) is associated with inferior patient-reported outcomes in addition to lateral column overload, increased risk for stress fractures of the fifth metatarsal, increased lateral plantar pressure, and pain.5,10,22 One such study demon-strated that overcorrection to an LIA of less than 5 degrees (adduction) was associated with significantly lower improvement in patient-reported outcomes compared to patients with residual midfoot abduction at mean 1.9 years following PCFD reconstruction with LCL.5 Another study demonstrated that 2-mm increments of LCL correction from 6 to 10 mm resulted in significant improvement of TN abduction as well as increased lateral plantar pres-sures, emphasizing that further overcorrection can result in substantially increased overload to the lateral column.22 In order to mitigate the risk for overcorrection, emphasis should be made to not overload the lateral column by maintaining passive eversion potential and passive range of motion.10 On the other hand, undercorrection of the lat-eral column in the setting of abduction can increase the risk for failure of reconstruction due to excess stress on medial soft tissues.15 Therefore, it is crucial that surgeons carefully titrate the amount of LCL correction. In a study investigating the use of trial wedges in LCL, investigators found that the average wedge size for adequate correction was 6.8 mm (range, 4-10). Given the overall results of these studies, the expert consensus is that the typical range of LCL performed is 5 to 10 mm of correction.

A Cotton osteotomy is performed to correct residual forefoot supination along the medial longitudinal arch after correction of the hindfoot valgus deformity.9,27 Traditionally, graft size is determined intraoperatively

Ellis et al 3

based on a combination of clinical judgement, trial grafts, and fluoroscopic assessment,19 with an average graft size reported in the literature ranging from 4 to 8 mm.14,28 Because undercorrection can increase risk for deformity recurrence and increased valgus thrust to the ankle and hindfoot, and overcorrection can cause excess loading of the medial column, with overpressure of the first metatar-sal head and sesamoids,8,18 methods to titrate the amount of correction have been studied. Previous work by Castaneda et al has defined a cuneiform articular angle as a reliable measurement of the effects of the Cotton oste-otomy at the medial cuneiform.2 A study performed by Kunas et al17 identified a linear correlation between graft size and degree of plantarflexion, in which an increase in graft size of 1 mm equates to 2 degrees’ increase in plan-tarflexion of the cuneiform articular angle. The authors also noted that the average amount of Cotton osteotomy performed in their cohort of 79 feet was 5.6 mm (SD 0.9).17 A subsequent study highlighted the importance of titration of the Cotton osteotomy, as excess plantarflexion defined as a cuneiform articular angle of less than negative 2 degrees has been associated with inferior patient-reported outcomes.8 Although the authors of this study noted an average graft size of 5.5 mm (range 4-10, SD 0.9) in their cohort of 63 feet, they also concluded that graft size alone did not correlate with changes in patient-reported outcomes, but rather the final postoperative posi-tion of the medial cuneiform.8

Although some studies have shown that instability of the first ray at the tarsometatarsal joint should be indicated for arthrodesis, there is no definitive contraindication for per-forming a Cotton osteotomy.25 Cotton osteotomy is a tech-nically easy operative option that has the advantage of preserving motion at the medial column.19 The combined expert experience of the authors suggest that clinical insta-bility of the first ray is not a clear contraindication and that careful patient selection should be made when considering a Cotton osteotomy in the setting of medial ray instability.

Given the averages reported and the titration methods for correcting forefoot supination, the expert consensus for the typical range of Cotton osteotomy performed is 5 to 11 mm of correction. The experts also agreed that mild/moderate clinical instability of the first ray would not preclude the use of a Cotton osteotomy.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055- 9998

Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

References

1. Arangio GA, Salathe EP. A biomechanical analysis of posterior tibial tendon dysfunction, medial displacement calcaneal oste-otomy and flexor digitorum longus transfer in adult acquired flat foot. Clin Biomech (Bristol, Avon). 2009;24(4):385-390.

2. Castaneda D, Thordarson DB, Charlton TP. Radiographic assessment of medial cuneiform opening wedge osteotomy for flatfoot correction. Foot Ankle Int. 2012;33(6):498-500.

3. Chan JY, Greenfield ST, Soukup DS, Do HT, Deland JT, Ellis SJ. Contribution of lateral column lengthening to correc-tion of forefoot abduction in stage IIb adult acquired flatfoot deformity reconstruction. Foot Ankle Int. 2015;36(12):1400-1411.

4. Chan JY, Williams BR, Nair P, Young E, Sofka C, Deland JT, Ellis SJ. The contribution of medializing calcaneal osteotomy on hindfoot alignment in the reconstruction of the stage II adult acquired flatfoot deformity. Foot Ankle Int. 2013;34(2): 159-166.

5. Conti MS, Chan JY, Do HT, Ellis SJ, Deland JT. Correlation of postoperative midfoot position with outcome following reconstruction of the stage II adult acquired flatfoot defor-mity. Foot Ankle Int. 2015;36(3):239-247.

6. Conti MS, Deland JT, Ellis SJ. Stage IIB flatfoot reconstruction using literature-based equations for heel slide and lateral column lengthening. Tech Foot Ankle Surg. 2017;16(4):153-166.

7. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal position of the heel following reconstruction of the stage II adult-acquired flatfoot deformity. Foot Ankle Int. 2015;36(8):919-927.

8. Conti MS, Garfinkel JH, Kunas GC, Deland JT, Ellis SJ. Postoperative medial cuneiform position correlation with patient-reported outcomes following cotton osteotomy for reconstruction of the stage II adult-acquired flatfoot defor-mity. Foot Ankle Int. 2019;40(5):491-498.

9. Deland JT. Adult-acquired flatfoot deformity. J Am Acad Orthop Surg. 2008;16(7):399-406.

10. Ellis SJ, Yu JC, Johnson AH, Elliott A, O’Malley M, Deland J. Plantar pressures in patients with and without lateral foot pain after lateral column lengthening. J Bone Joint Surg Am. 2010;92(1):81-91.

11. Guha AR, Perera AM. Calcaneal osteotomy in the treat-ment of adult acquired flatfoot deformity. Foot Ankle Clin. 2012;17(2):247-258.

12. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis WH, Manoli A. Adult acquired flatfoot deformity. Foot Ankle Int. 2011;32(1):95-101.

13. Hintermann B, Valderrabano V, Kundert HP. Lateral column lengthening by calcaneal osteotomy combined with soft tissue

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reconstruction for treatment of severe posterior tibial tendon dysfunction. Technique and preliminary results. Orthopade. 1999;28(9):760-769.

14. Hirose CB, Johnson JE. Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed fore-foot varus associated with flatfoot deformity. Foot Ankle Int. 2004;25(8):568-574.

15. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc-tion. Foot Ankle Clin. 2017;22(3):613-624.

16. Kitaoka HB, Kura H, Luo ZP. Calcaneocuboid distraction arthrodesis for posterior tibial tendon dysfunction and flatfoot: a cadaveric study. Clin Orthop Relat Res. 2000;381:241-247.

17. Kunas GC, Do HT, Aiyer A, Deland JT, Ellis SJ. Contribution of medial cuneiform osteotomy to correction of longitudinal arch collapse in stage IIb adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(8):885-893.

18. Lutz M, Myerson M. Radiographic analysis of an opening wedge osteotomy of the medial cuneiform. Foot Ankle Int. 2011;32(3):278-287.

19. McCormick JJ, Johnson JE. Medial column procedures in the correction of adult acquired flatfoot deformity. Foot Ankle Clin. 2012;17(2):283-298.

20. Mosier-Laclair S, Pomeroy G, Manoli A. Operative treat-ment of the difficult stage 2 adult acquired flatfoot deformity. Foot Ankle Clin. 2001;6(1):95-119.

21. Myerson MS, Badekas A, Schon LC. Treatment of stage II posterior tibial tendon deficiency with flexor digitorum lon-gus tendon transfer and calcaneal osteotomy. Foot Ankle Int. 2004;25(7):445-450.

22. Oh I, Imhauser C, Choi D, Williams B, Ellis S, Deland J. Sensitivity of plantar pressure and talonavicular alignment to lateral column lengthening in flatfoot reconstruction. J Bone Joint Surg Am. 2013;95:1094-1100.

23. Saltzman CL, El-Khoury GY. The hindfoot alignment view. Foot Ankle Int. 1995;16(9):572-576.

24. Saunders SM, Ellis SJ, Demetracopoulos CA, Marinescu A, Burkett J, Deland JT. Comparative outcomes between step-cut lengthening calcaneal osteotomy vs traditional Evans osteotomy for stage IIB adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(1):18-27.

25. Tankson CJ. The Cotton osteotomy: indications and tech-niques. Foot Ankle Clin. 2007;12(2):309-315.

26. Vander Griend R. Lateral column lengthening using a “Z” osteotomy of the calcaneus. Tech Foot Ankle Surg. 2008;7(4):257-263.

27. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of the adult acquired flatfoot deformity. Curr Rev Musculoskelet Med. 2013;6:294-303.

28. Yarmel D, Mote G, Treaster A. The Cotton osteotomy: a technical guide. J Foot Ankle Surg. 2009;48(4):506-512.

https://doi.org/10.1177/1071100720950742

Foot & Ankle International® 1 –5© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950742journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted

CONSENSUS STATEMENT ONE: Even though there is still a great deal of uncertainty in soft tissue reconstruction for severe progressive collapsing foot deformity, if lateral column lengthening does not fully correct the abduction deformity, we recommend consid-ering medial soft tissue procedures (Spring ligament/Superficial and Deep Deltoid repair/reconstruction) or a talonavicular fusion.Delegate vote: agree, 100% (9/9); disagree, 0% (0/9); abstain, 0% (0/9).(Unanimous, strongest consensus)CONSENSUS STATEMENT TWO: Even though the results and efficacy of medial soft tissue reconstruction procedures (Spring ligament/Deep and Superficial Deltoid) are currently unknown (anecdotal), they should be considered as a joint-sparing alternative in the presence of valgus deformity of the ankle joint if there is less than 50% cartilage loss on the joint’s lat-eral side. Deformities with more than 50% of lateral cartilage loss should be considered for ankle fusion/replacement.Delegate vote: agree, 89% (8/9); disagree, 0% (0/9); abstain, 11% (1/9).(Strong consensus)

Rationale

Progressive collapsing flatfoot deformity (PCFD) is a com-plex disorder that is secondary to degeneration of the medi-ally positioned soft tissue structures that include multiple ligaments of the foot and ankle, as well as the posterior tibial tendon (PTT). This soft tissue failure leads to valgus and abduction deformity of the hindfoot and midfoot resulting in progressive collapse of the medial longitudinal arch, and less commonly, valgus talar tilt at the ankle.6,9,10,11,15

950742 FAIXXX10.1177/1071100720950742Foot & Ankle InternationalDeland et alresearch-article2020

1Hospital for Special Surgery, New York, NY, USA2Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA3Kantonspital Baselland4Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA5University of Washington, Seattle, WA, USA6Mercy Medical Center, Baltimore, MD, USA7New York University Grossman School of Medicine, New York, NY, USA8Johns Hopkins School of Medicine, Baltimore, MD, USA 9Georgetown School of Medicine, Washington, DC, USA10Cedars-Sinai Medical Center, Los Angeles, CA, USA11Washington University School of Medicine, St. Louis, MO, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Indications for Deltoid and Spring Ligament Reconstruction in Progressive Collapsing Foot Deformity

Jonathan T. Deland, MD1, Scott J. Ellis, MD1 , Jonathan Day, MS1 , Cesar de Cesar Netto, MD, PhD2 , Beat Hintermann, MD3, Mark S. Myerson, MD4, Bruce J. Sangeorzan, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, and Jeffrey E. Johnson, MD11

AbstractRecommendation: There is evidence supporting medial soft tissue reconstruction, such as spring and deltoid ligament reconstructions, in the treatment of severe progressive collapsing foot deformity (PCFD). We recommend spring ligament reconstruction to be considered in addition to lateral column lengthening or subtalar fusion at the initial operation when those procedures have given at least 50% correction but inadequate correction of the severe flexible subluxation of the talonavicular and subtalar joints. We also recommend combined flatfoot reconstruction and deltoid reconstruction be considered as a joint sparing alternative in the presence of PCFD with valgus deformity of the ankle joint if there is 50% or more of the lateral joint space remaining.Level of Evidence: Level V, expert opinion.

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, spring ligament, progressive collapsing foot disorder, PCFD

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The ligament pathology is as prevalent or even more impor-tant than the posterior tibial tendinopathy.12 The ligament failure indeed creates the biggest problem, the progressive collapse of the foot and possible involvement of the ankle. In the severe deformities of this condition, joint-sparing corrective procedures may be inadequate and necessitate fusion of critical joints to allow adequate deformity correc-tion and to provide proper stability. Ligament reconstruc-tion procedures, rather than repair and tightening of degenerated weak ligaments, may allow for preservation of critical joints when there is adequate remaining motion in those joints. The bony procedures at the time of the opera-tion must give 50% or more correction of these joints. In order to consider ligament reconstruction, preoperative stress radiographs must demonstrate full correction of the deformity at that joint. There is some evidence that recon-struction of the ligaments of these joints in addition to bony realignment procedures can give adequate correction of alignment and good functional outcomes in the severe flex-ible deformities.8,13,14,32 This allows for the avoidance of fusions of critical joints in properly selected patients.

Spring Ligament

Anatomically, the spring ligament spans from the susten-taculum tali of the calcaneus to the navicular bone and is composed mainly of the superomedial and inferior calca-neonavicular ligaments.2 Functionally, the spring ligament acts as a main stabilizer of the medial arch and the primary static support of the talonavicular (TN) joint.3,7,9,10,15,30 Biomechanical studies have demonstrated that releasing the spring ligament and cyclically loading the foot creates PCFD.9 The integral role played by the spring ligament is evident as it is the most commonly and severely affected ligament in PCFD, with almost all patients having some degree of spring ligament degeneration.12 Biomechanically, this degeneration leads to combined plantar sag, abduction, and valgus through the TN and subtalar (ST) joints, with flattening of the medial longitudinal arch as the foot dis-places from underneath the talus (peritalar subluxation).31

Studies have demonstrated various techniques in addressing dysfunction of the spring ligament.1 Direct repair has been tried but with poor deformity correction clinically and radiographically.2,15,26 Spring ligament reconstruction allows for the use of strong nondegener-ated tendon graft. Tendon autograft or allograft has supe-rior biomechanical properties compared with simple repair and can better withstand stress forces across the TN joint and therefore can maintain correction with the help of bony procedures.9 Reconstruction has been tried using the superficial deltoid ligament,10 peroneus longus,6,30,32 flexor hallucis longus autografts,22 and Achilles tendon allograft.13 Overall, previous studies have demonstrated efficacious results, including both good clinical outcomes

and radiographic correction.6,8,16,20,30,32 One such study by Williams et al32 demonstrated such results at a mean of 8.9 years’ follow-up. These patients underwent spring ligament reconstruction with peroneus longus autograft tendon transfer and maintained long-term improvement in multiple patient-reported outcomes measures (American Orthopaedic Foot & Ankle Society hindfoot score, Foot and Ankle Outcome Score, 36-Item Short Form Health Survey) as well as radiographic correction and eversion strength.32 In this study, none of the patients went on to need additional joint fusions.

In a more recent study of 14 feet by Brodell et al,5 spring ligament reconstruction was indicated in the cor-rection of flexible PCFD after lateral column lengthening, medial displacement calcaneal osteotomy, and first ray procedures resulted in inadequate intraoperative correc-tion of the TN joint. Using similar intraoperative operative algorithm utilized by Williams et al,32 the surgeon was prepared for in the setting of a severe flexible deformity to proceed in properly selected patients with spring ligament reconstruction. Such patients were identified intraopera-tively when the bony procedures can correct up to 50% the bony realignment of the TN joint, but inadequate correc-tion would still remain. Patients achieved good correction in anteroposterior talonavicular and sagittal alignment measurements as well as good functional outcomes.5,32 The technique of the spring ligament reconstruction was somewhat different and used allograft tendon rather than autograft. All but one patient were satisfied. That patient developed a medial navicular stress fracture with loss of correction, indicating the need in the technique to preserve adequate bone stock of the medial wall of the navicular, to avoid stress reaction/fractures and loss of correction.

Patients can have more TN deformity in the anteroposte-rior plane than sagittal plane of the foot, or vice versa. This stems most likely from involvement of one part of the spring ligament more than the other. In the opinion of the senior author of this consensus article, the TN joint must be cor-rected by 50% in all planes for a spring ligament reconstruc-tion to be successful. In the most common method of the senior author’s version of spring ligament reconstruction, the tendon graft goes from the plantar navicular to the medial malleolus of the tibia. Adequate correction should be con-firmed intraoperatively. If plantar TN sag is the worst defor-mity, reconstruction may need to be done primarily from the plantar navicular to the calcaneus with a smaller graft to the tibia. For a severe plantar sag deformity noted preoperatively, ST fusion may be chosen, and spring ligament reconstruction can be added with either of the 2 techniques, aiming to obtain good alignment of the TN joint in all planes. Subluxation of the ST joint in the coronal plane, usually associated with sub-fibular impingement of the calcaneus against the fibula, may be secondary to insufficiency of the talocalcaneal interosseus ligament. This should be checked for on preoperative

Deland et al 3

WEIGHTBEARING imaging, intraoperative inspection at the level of the distal tip of the fibula, and checking for an intact interosseus ligament. Often the ligament cannot be fully seen intraoperatively. However, it can be palpated with an elevator and good tension confirmed. Also, the ligament can be evalu-ated preoperatively with a magnetic resonance imaging scan. Certainly, clear subfibular impingent is not likely to be reduced by spring ligament reconstruction. With the use of WEIGHTBEARING computed tomographic (CT) scans for preoperative evaluation, such impingement or severe anterior subluxation of the talus on the calcaneus can be easily assessed and if present a subtalar fusion would be the most reliable option. At this time, it is not known if mild cases of subfibular impingement or cases of severe sinus tarsi impingement with the tip of the lateral process of the talus migrating up the anterior process of the calcaneus, can be treated with spring ligament reconstruction. This will require studies with pre- and postoperative WEIGHTBEARING CTs. It is not expected that a spring ligament reconstruction will be a satisfactory reconstruction of the interosseous liga-ment. It is more likely that certain amounts of sinus tarsi (sub-talar) impingement can be corrected. Documentation of these amounts await studies with postoperative WEIGHTBEARING CTs. A primary reason for spring ligament reconstruction is to avoid TN fusion. If such a fusion is done, there is loss of all TN motion and nearly all ST motion, resulting in loss of func-tion and stress on the ankle joint.2,29 The senior author acknowledges that not all TN joint motion is preserved with spring ligament reconstruction, but with experience approxi-mately half of this key motion can be preserved. The tension of the reconstruction should be adjusted to just slight over-correction, to avoid both overcorrection and inadequate cor-rection, thereby preserving motion of the joint and avoiding stiffness. Indications when a TN fusion should be performed are fixed deformity on preoperative inversion stress conven-tional radiographic imaging showing that the TN joint cannot be inverted, severe arthritis of the TN joint, and failure for the reconstruction to correct the TN abduction and/or plantar sag intraoperatively.

Despite good results, with a total of only 28 feet from 2 institutions, a high level of recommendation cannot yet be given for spring ligament reconstruction. Recommendation of Level C is reasonable because additional studies are needed. A long-term follow-up study with more patients is in progress. However, the present studies do demonstrate that preservation of the TN joint, and sometimes the ST joint, can be achieved in very severe flexible deformities when the bony realignment procedures do not give adequate correction. It requires proper intraoperative assessment as mentioned above.

Deltoid Ligament

Anatomically, the deltoid ligament complex is a broad strong structure that can be divided into 2 main components:

superficial and deep.4 Because it provides rotatory and valgus stability of the ankle,18,28 failure of both components of the deltoid ligament results in medial ankle instability and intra-articular ankle valgus tilt as seen in late-stage PCFD. According to the new classification system by Myerson in the present consensus group, the valgus ankle tilt patients can be IE, ankle instability (flexible deformity), or rigid ankle val-gus, IIE. The ankle valgus tilt can be identified on a WEIGHTBEARING anteroposterior conventional radio-graphs of the ankle.25,31 The IE patients correspond to the Bluman et al IVA, supple tibiotalar valgus, category. The treatment of PCFD IE patients is widely recognized as chal-lenging. However, there is evidence in the literature to sup-port that improvement of the talar tilt and good function can be gained from combined deltoid ligament reconstruction and correction of the foot deformity. Unfortunately, there are only a few articles with talar tilt measurements pre- and postopera-tively. The number of patients in each study is small.11,14,19

The challenging nature of this operation should be acknowledged. The operation requires good correction of the bony realignment in the hindfoot, midfoot, and forefoot as well as reconstruction of the deltoid ligament. The results reported in the literature are not uniformly good. For exam-ple, one article described all patients who had hindfoot fusions ended up with an increased valgus talar tilt postop-eratively.27 In the same study, patients who did not have hindfoot fusions, but had other bony realignment proce-dures, did not have improvement of talar tilt. However, they also did not have progression of talar tilt deformity with short-term follow-up.27

Different techniques of deep and superficial deltoid reconstructions are described in the literature.5,11,14,17,21,23,24,27 There is likely to be variability in how authors correct the accompanying foot deformity in stage IE patients PCFD. This makes comparison of outcomes related to combined deltoid and reconstruction problematic.

The following is a summary of the literature. Two arti-cles have given technique descriptions but no clinical out-come data.21,23 Another article described good biomechanical testing of a technique as well as including conventional radiographic findings of 2 patients with good deformity correction postoperatively.17 An addendum to the article mentioned that the author had performed 8 such procedures and has a clinical trial underway.17 Two other articles pre-sented a tibionavicular-calcaneal ligament reconstruction for PCFD, a combined spring-deltoid ligament reconstruc-tion, but did not report ankle joint measurements.5,24

Aside from the articles mentioned above, there are 3 articles in the literature that report pre-and postoperative talar tilt measurements as well as clinical outcomes. All 3 articles are Level IV studies.11,14,19 The first 2 articles have the same series of 5 patients, one with early and the other with longer term follow-up. The 5 patients were first reported in 2004 with minimum 2-year follow-up of a deep

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deltoid reconstruction using peroneus longus autograft and flatfoot correction.11 There was one failure, defined by a patient with 9 degrees of valgus talar tilt remaining, rather than the 4 degrees required for success. The second article by Ellis et al14 reported on the same patient cohort but with an average of 8.9-year follow-up. The failure patient had progressed from mild to moderate pain but with no increase in the tilt. All patients in the study were satisfied with the procedure. Except for the failure patient, the patients had either no or mild pain at the average 8.9-year follow-up. Conventional WEIGHTBEARING radiographs showed all patients had maintained their correction. The third article by Jeng et al was from a different institution and had 8 patients with an average 3-year follow-up.19 Three of the 8 patients were considered a failure for not having met the criteria of success, defined as 3 degrees or less postopera-tive talar tilt with greater than 2 mm lateral joint space remaining. Five patients met the criteria for success. The 3 patients who failed were found to have more severe ankle deformity preoperatively when compared to the patients who gained successful correction.

The senior author is presently working on a review of a much larger series of patients with longer follow-up. The find-ings so far strongly suggest maintenance of correction and improved function. A good candidate for the procedure is defined as a patient with 50% or more of ankle lateral joint space remaining on WEIGHTBEARING conventional radio-graph. It should be emphasized that a clinically straight heel (no residual clinical heel valgus), good alignment of the TN joint, and a stable first ray with the metatarsal head slightly prominent in comparison to the second metatarsal are prerequisite for a successful deltoid reconstruction. It should be achieved either before or at the time of the deltoid reconstruction.

A high level of recommendation for deltoid reconstruction combined with PCFD reconstruction cannot be given based on the present literature. There are only 3 published studies with tilt measurements, 2 of which have the same patients. All 3 studies have very few patients, for a total of 13.11,14,19 Therefore, the level of recommendation is I (insufficient). The paucity of data to support this combined procedure should be explained to patients. Although there is insufficient data to date to give even a fair recommendation, the literature shows that talar tilt correction to good alignment and good function is possible. More studies are needed.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

References

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2. Astion DJ, Deland JT, Otis JC, Kenneally S. Motion of the hindfoot after simulated arthrodesis. J Bone Joint Surg. 1997;79(2):241-246.

3. Bastias GF, Dalmau-Pastor M, Astudillo C, Pellegrini MJ. Spring ligament instability. Foot Ankle Clin. 2018;23(4): 659-678.

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15. Gazdag AR, Cracchiolo A III. Rupture of the posterior tibial tendon. evaluation of injury of the spring ligament and clinical

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assessment of tendon transfer and ligament repair. J Bone Joint Surg. 1997;79(5):675-681.

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17. Haddad SL, Dedhia S, Ren Y, Rotstein J, Zhang L. Deltoid ligament reconstruction: a novel technique with biomechani-cal analysis. Foot Ankle Int. 2010;31(7):639-651.

18. Harper MC. Deltoid ligament: an anatomical evaluation of function. Foot Ankle. 1987;8(1):19-22.

19. Jeng CL, Bluman EM, Myerson MS. Minimally invasive del-toid ligament reconstruction for stage IV flatfoot deformity. Foot Ankle Int. 2011;32(1):21-30.

20. Kelly M, Masqoodi N, Vasconcellos D, et al. Spring ligament tear decreases static stability of the ankle joint. Clin Biomech. 2019;61:79-83.

21. Lack W, Phisitkul P, Femino JE. Anatomic deltoid ligament repair with anchor-to-post suture reinforcement: Technique tip. Iowa Orthop J. 2012;32:227-230.

22. Lee WC, Yi Y. Spring ligament reconstruction using the autogenous flexor hallucis longus tendon. Orthopedics. 2014; 37(7):467-471.

23. Lui TH. Endoscopic repair of the superficial deltoid ligament and spring ligament. Arthrosc Tech. 2016;5(3):e621-e625.

24. Nery C, Lemos, André Vitor Kerber C, Raduan F, Mansur NSB, Baumfeld D. Combined spring and deltoid ligament repair in adult-acquired flatfoot. Foot Ankle Int. 2018;39(8):903-907.

25. Oburu E, Myerson MS. Deltoid ligament repair in flatfoot deformity. Foot Ankle Clin. 2017;22(3):503-514.

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31. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of the adult acquired flatfoot deformity. Curr Rev Musculoskelet Med. 2013;6(4):294-303.

32. Williams BR, Ellis SJ, Deyer TW, Pavlov H, Deland JT. Reconstruction of the spring ligament using a peroneus longus autograft tendon transfer. Foot Ankle Int. 2010;31(7):567-577.

https://doi.org/10.1177/1071100720950747

Foot & Ankle International® 1 –4© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950747journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted1. CONSENSUS STATEMENT 1—We recommend

performing a medializing displacement calcaneal osteotomy (MDCO) as an isolated bony procedure when there is an isolated hindfoot valgus, with ade-quate talonavicular joint coverage (less than 35%-40% uncoverage) and lack of significant forefoot supination, varus, or abduction.

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%

(Unanimous, Strongest Consensus)2. CONSENSUS STATEMENT 2—The clinical goal

of hindfoot valgus correction with a medial displace-ment calcaneal osteotomy (MDCO) is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles tendon and distal aspect of the leg.

950747 FAIXXX10.1177/1071100720950747Foot & Ankle InternationalSchon et alresearch-article2020

1Mercy Medical Center, Baltimore, MD, USA2New York University Grossman School of Medicine, New York, NY, USA3Johns Hopkins School of Medicine, Baltimore, MD, USA4Georgetown School of Medicine, Washington, DC, USA5Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA6Hospital for Special Surgery, New York, NY, USA7Kantonspital Baselland, Liestal, Switzerland8Washington University School of Medicine, St. Louis, MO, USA9Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA10University of Washington, Seattle, WA, USA11Cedars-Sinai Medical Center, Los Angeles, CA, USA

Corresponding Author:Cesar de Cear Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA.Email: cesar-netto@uiowa.edu

Consensus for the Indication of a Medializing Displacement Calcaneal Osteotomy in the Treatment of Progressive Collapsing Foot Deformity

Lew C. Schon, MD1,2,3,4, Cesar de Cesar Netto, MD, PhD5 , Jonathan Day, MS6 , Jonathan T. Deland, MD6, Beat Hintermann, MD7, Jeffrey E. Johnson, MD8 , Mark S. Myerson, MD9, Bruce J. Sangeorzan, MD10, David Thordarson, MD11, and Scott J. Ellis, MD6

AbstractRecommendation: There is evidence that the medial displacement calcaneal osteotomy (MDCO) can be effective in treating the progressive collapsing foot deformity (PCFD). This juxta-articular osteotomy of the tuberosity shifts the mechanical axis of the calcaneus from a more lateral position to a more medial position, which provides mechanical advantage in the reconstruction for this condition. This also shifts the action of the Achilles tendon medially, which minimizes the everting deforming effect and improves the inversion forces. When isolated hindfoot valgus exists with adequate talonavicular joint coverage (less than 35%-40% uncoverage) and a lack of significant forefoot supination, varus, or abduction, we recommend performing this osteotomy as an isolated bony procedure, with or without additional soft tissue procedures. The clinical goal of the hindfoot valgus correction is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles tendon and distal aspect of the leg. The typical range when performing a MDCO, while considering the location and rotation of the osteotomy, is 7 to 15 mm of correction.Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, hindfoot valgus, medial displacement calcaneal osteotomy, MDCO, medial slide, calcaneal osteotomy, progressive collapsing foot deformity, PCFD

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Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%

(Unanimous, Strongest Consensus)3. CONSENSUS STATEMENT 3—The typical range

when performing a medializing calcaneal osteotomy, while considering the location and rotation of the osteotomy, is 7 to 15 mm of correction.

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%

(Unanimous, Strongest Consensus)4. CONSENSUS STATEMENT 4—The following

WEIGHTBEARING conventional radiographic incidences are considered mandatory by the consen-sus group in the assessment of progressive collaps-ing foot deformity (PCFD) patients: anteroposterior (AP) foot, AP or mortise ankle, lateral foot. The consensus group also strongly recommends a hind-foot alignment view when available.

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Abstain: 0%

(Unanimous, Strongest Consensus)

Rationale

The purpose of the medial displacement calcaneal osteot-omy (MDCO) is to restore normal hindfoot alignment in the surgical treatment of progressive collapsing foot deformity (PCFD). To date, there has been no general consensus regarding when to perform the MDCO. In addition, there is no general consensus on the goals of this osteotomy or on the range of correction possible. Such guidelines are essen-tial to help achieve optimal surgical correction and maxi-mize patient outcomes.

The MDCO is performed to correct mainly the valgus hindfoot deformity, specifically as a key mechanical element to improving the alignment of the leg with respect to the heel during weightbearing. It also shifts the moment arm of the Achilles tendon in a medial direction, which changes the leverage about the axis of rotation of the subtalar joint, con-verting it from an eversion deforming force,10,20,23 alleviat-ing the contribution of Achilles tension to worsening deformity progression.9 Nyska et al23 demonstrated that fol-lowing MDCO, Achilles loading contributed less to arch collapse, suggesting the powerful role of MDCO in not only correcting the existing deformity but also preventing further progression. Restoration of hindfoot alignment is critical to prevent failure of the reconstruction and to correct the abnor-mal gait kinematics that can accompany hindfoot valgus deformity.26 In addition, MDCO redistributes plantar pres-sures of the collapsed foot by shifting medial pressures more laterally.13 Numerous studies have demonstrated the utility of MDCO to decrease the strain on the medial soft tissue structures such as the spring and deltoid ligaments, as well

as the posterior tibial tendon (PTT).24 It has also been shown to restore foot alignment,21,27 stabilize forces at the talona-vicular joint,1 and improve patient outcomes.3,7,11,18 Studies have demonstrated that tendon transfers alone, such as a flexor digitorum longus (FDL) tendon transfer to the navicu-lar tuberosity, do not result in acceptable biomechanical or clinical outcomes following PCFD reconstruction and that the foot remains deformed and prone to failure with time.8,15-17 Therefore, osseous correction of the deformity is necessary for long-term maintenance of correction and clini-cal outcomes.20

In a study of 129 patients with flexible PCFD, correc-tion with tendon transfer and MDCO resulted in significant improvement in surgical outcomes at a mean 5.2 years fol-lowing reconstruction. Specifically, the authors noted sig-nificant and sustained improvement in patient-reported outcomes (American Orthopaedic Foot & Ankle Society, Short Form–36), clinical strength, radiographic and clini-cal deformity correction, and pain relief, with 92% of patients entirely satisfied at final follow-up.20 Improvements in objective and subjective clinical outcomes correlated with improvements in radiographic correction, therefore suggesting that by correcting the heel malalignment defor-mity, MDCO improves upon the benefits of tendon transfer alone. It is important to note that patients with more than 15 degrees of fixed forefoot varus deformity were excluded from this study.20

Indeed, the specific clinical indication for an isolated MDCO is a PCFD patient with an increased valgus hind-foot alignment and a flexible, nonarthritic foot that can be passively manipulated into good alignment. If there is sig-nificant forefoot varus or abduction, additional bony cor-rective procedures would be needed to fully correct the deformity.9,10 Contraindications include rigid PCFD and significant hindfoot arthritis.20 In a study by Niki et al,22 the authors noted that preoperative conventional radio-graphic findings of a lateral talus–first metatarsal angle exceeding 25 degrees and a hindfoot alignment view tibio-calcaneal angle greater than 15 degrees would be associ-ated with failure to maintain adequate correction following FDL transfer and MDCO, with an average 5.6 years of follow-up. Also, from a conventional WEIGHTBEARING radiographic perspective, it is the opinion of the consensus experts that the use of MDCO as an isolated bony proce-dure should only be considered when the talonavicular (TN) joint uncoverage, assessed on anteroposterior foot views, is less than 35% to 40%. If there is over 35% to 40% TN uncoverage, the authors have suggested performing additional realignment procedures such as lateral column lengthening (LCL) and/or joint fusions.14,20

The clinical goal of hindfoot valgus correction is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles

Schon et al 3

tendon and distal aspect of the leg. This is achieved in the operating room and is appreciated by visual and tactile means. Oftentimes during the surgery, the leg can be held up from the operating table and viewed from the posterior perspective. Studies have shown that a clinically neutral heel is in fact radiographically in a neutral alignment or mild varus, as measured by the hindfoot moment arm (HMA) in the hindfoot alignment view.3,25 A previous study by Conti et al3 in a cohort of 55 patients with flexible PCFD not only showed that a neutral or mild radiographic varus alignment, defined as an HMA of 0 to 5 mm, is equivalent to a clinically neutral heel but that this was also associated with superior patient-reported outcomes com-pared to patients with a residual valgus alignment or increased moderate varus overcorrection. In addition, the authors found no correlation between the amount of MDCO displacement and improvement in patient-reported outcomes, suggesting that successful surgical outcomes may be influenced by the final position of the heel rather than the actual amount corrected.

Preoperative planning should include a detailed clinical and radiographic assessment of the hindfoot alignment, keeping in mind that the clinical assessment has been shown to underestimate the bony hindfoot valgus deformity by an average of 11 to 12.8 degrees.4 The expert consensus is for WEIGHTBEARING conventional radiographic assess-ment to be performed via the hindfoot alignment view, when available, with the HMA representing an accurate and reliable parameter in quantifying deformity.25 Use of WEIGHTBEARING computed tomography (WBCT) is also advocated for preoperative planning, when available.5,6

While the literature attempts to provide guidance that the shift should be around 10 mm,1,2,10,12,19,20 what occurs prac-tically is that the surgeon shifts the heel based on the degree of the deformity, their sense of what the optimal alignment should be in each given case, and also according to what the soft tissue tensioning allows. The consensus expert opinion is that the typical range when performing a MDCO, aiming to achieve a neutrally aligned heel, is 7 to 15 mm of medial displacement correction, depending on the severity of the deformity. The literature supports that when pursuing ade-quate hindfoot alignment correction, the use of validated HMA measurements on the hindfoot alignment view repre-sents an attractive surgical planning tool.25 Chan et al2 derived a linear equation relating the change between preop-erative and postoperative HMA with the amount of intraop-eratively measured MDCO, demonstrating that a medial translation of 1 mm corresponds to approximately a 1.5-mm change in radiographic HMA. As mentioned earlier, mild radiographic overcorrection of 0 to 5 mm varus resulted in a clinically straight heel and superior patient-reported outcomes.3 In these 2 latter studies,2,3 the magnitude of the MDCO shift varied between patients based on severity of

the deformity. Again, given the results of these studies and the end goal of achieving a clinically straight heel, the expert consensus is that the typical range of MDCO displacement is 7 to 15 mm.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055- 9998Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

References

1. Arangio GA, Salathe EP. A biomechanical analysis of pos-terior tibial tendon dysfunction, medial displacement cal-caneal osteotomy and flexor digitorum longus transfer in adult acquired flat foot. Clin Biomech (Bristol, Avon). 2009; 24(4):385-390.

2. Chan JY, Williams BR, Nair P, et al. The contribution of medializing calcaneal osteotomy on hindfoot alignment in the reconstruction of the stage II adult acquired flatfoot defor-mity. Foot Ankle Int. 2013;34(2):159-166.

3. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal position of the heel following reconstruction of the stage II adult-acquired flatfoot deformity. Foot Ankle Int. 2015;36(8): 919-927.

4. de Cesar Netto C, Kunas GC, Soukup D, Marinescu A, Ellis SJ. Correlation of clinical evaluation and radiographic hind-foot alignment in stage II adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(7):771-779.

5. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible adult acquired flatfoot deformity: comparison between weight-bearing and non-weight-bearing measurements using cone-beam computed tomography. J Bone Joint Surg Am. 2017; 99(18):e98.

6. de Cesar Netto C, Shakoor D, Roberts L, et al. Hindfoot align-ment of adult acquired flatfoot deformity: a comparison of clinical assessment and weightbearing cone beam CT exami-nations. Foot Ankle Surg. 2019;25(6):790-797.

7. Fayazi AH, Nguyen HV, Juliano PJ. Intermediate term fol-low-up of calcaneal osteotomy and flexor digitorum longus transfer for treatment of posterior tibial tendon dysfunction. Foot Ankle Int. 2002;23(12):1107-1111.

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8. Funk DA, Cass J, Johnson K. Acquired adult flat foot second-ary to posterior tibial-tendon pathology. J Bone Joint Surg Am. 1986;68(1):95-102.

9. Greenfield S, Cohen B. Calcaneal osteotomies: pearls and pitfalls. Foot Ankle Clin. 2017;22(3):563-571.

10. Guha AR, Perera AM. Calcaneal osteotomy in the treat-ment of adult acquired flatfoot deformity. Foot Ankle Clin. 2012;17(2):247-258.

11. Guyton GP, Jeng C, Krieger LE, Mann RA. Flexor digitorum longus transfer and medial displacement calcaneal osteotomy for posterior tibial tendon dysfunction: a middle-term clinical follow-up. Foot Ankle Int. 2001;22(8):627-632.

12. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis WH, Manoli A. Adult acquired flatfoot deformity. Los Angeles, CA: Sage; 2011.

13. Hadfield MH, Snyder JW, Liacouras PC, Owen JR, Wayne JS, Adelaar RS. Effects of medializing calcaneal osteotomy on Achilles tendon lengthening and plantar foot pressures. Foot Ankle Int. 2003;24(7):523-529.

14. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc-tion. Foot Ankle Clin. 2017;22(3):613-624.

15. Johnson KA. Tibialis posterior tendon rupture. Clin Orthop Relat Res. 1983(177):140-147.

16. Kitaoka HB, Luo Z-P, An K-N. Reconstruction operations for acquired flatfoot: biomechanical evaluation. Foot Ankle Int. 1998;19(4):203-207.

17. Mann RA, Thompson F. Rupture of the posterior tibial ten-don causing flat foot: surgical treatment. J Bone Joint Surg Am. 1985;67(4):556-561.

18. Moseir-LaClair S, Pomeroy G, Manoli A II. Intermediate follow-up on the double osteotomy and tendon transfer

procedure for stage II posterior tibial tendon insufficiency. Foot Ankle Int. 2001;22(4):283-291.

19. Mosier-LaClair S, Pomeroy G, Manoli A. Operative treat-ment of the difficult stage 2 adult acquired flatfoot deformity. Foot Ankle Clin. 2001;6(1):95-119.

20. Myerson MS, Badekas A, Schon LC. Treatment of stage II posterior tibial tendon deficiency with flexor digitorum longus tendon transfer and calcaneal osteotomy. Foot Ankle Int. 2004;25(7):445-450.

21. Myerson MS, Corrigan J, Thompson F, Schon LC. Tendon transfer combined with calcaneal osteotomy for treatment of posterior tibial tendon insufficiency: a radiological investiga-tion. Foot Ankle Int. 1995;16(11):712-718.

22. Niki H, Hirano T, Okada H, Beppu M. Outcome of medial displacement calcaneal osteotomy for correction of adult-acquired flatfoot. Foot Ankle Int. 2012;33(11):940-946.

23. Nyska M, Parks BG, Chu IT, Myerson MS. The contribution of the medial calcaneal osteotomy to the correction of flatfoot deformities. Foot Ankle Int. 2001;22(4):278-282.

24. Otis JC, Deland JT, Kenneally S, Chang V. Medial arch strain after medial displacement calcaneal osteotomy: an in vitro study. Foot Ankle Int. 1999;20(4):222-226.

25. Saltzman CL, El-Khoury GY. The hindfoot alignment view. Foot Ankle Int. 1995;16(9):572-576.

26. Svoboda Z, Honzikova L, Jaroszczuk S, Vidal T, Martinaskova E. Kinematic gait analysis in children with valgus deformity of the hindfoot. Acta Bioeng Biomech. 2014;16(3):89-93.

27. Vora AM, Tien TR, Parks BG, Schon LC. Correction of mod-erate and severe acquired flexible flatfoot with medializing calcaneal osteotomy and flexor digitorum longus transfer. J Bone Joint Surg Am. 2006;88(8):1726-1734.

https://doi.org/10.1177/1071100720950759

Foot & Ankle International® 1 –4© The Author(s) 2020Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/1071100720950759journals.sagepub.com/home/fai

Topical Review

Consensus Statements Voted:

CONSENSUS STATEMENT ONE: In general, we aim to maximize preservation of joint range of motion and mobility. When given the choice of surgical proce-dures, we recommend preserving joint motion.Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%.(Unanimous, strongest consensus)CONSENSUS STATEMENT TWO: Talonavicular (TN) joint fusion should be considered in the arthritic and stiff joints, important sagittal plane sagging of the TN joint, severe deformities, as well as in cases where inadequate correction of the TN abduction deformity is achieved intraoperatively.Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, 11% (1/9).(Strong consensus)CONSENSUS STATEMENT THREE: Patients with high BMI, defined as a BMI equal to or higher than 30, will generally do worse with reconstructive surgery when compared to hindfoot fusions. However, in

younger patients, attempts should be made for joint pres-ervation procedures.Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9).(Strong consensus)

950759 FAIXXX10.1177/1071100720950759Foot & Ankle InternationalSangeorzan et alreview-article2020

1University of Washington, Seattle, WA, USA2Kantonspital Baselland, Liestal, Switzerland3Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA4Hospital for Special Surgery, New York, NY, USA5Washington University School of Medicine, St. Louis, MO, USA6Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA7Mercy Medical Center, Baltimore, MD, USA 8New York University Grossman School of Medicine, New York, NY, USA9Johns Hopkins School of Medicine, Baltimore, MD, USA10Georgetown School of Medicine, Washington, DC, USA11Cedars-Sinai Medical Center, Los Angeles, CA, USA

Corresponding Author:Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: cesar-netto@uiowa.edu

Progressive Collapsing Foot Deformity: Consensus on Goals for Operative Correction

Bruce J. Sangeorzan, MD1, Beat Hintermann, MD2, Cesar de Cesar Netto, MD, PhD3 , Jonathan Day, MS4 , Jonathan T. Deland, MD4, Scott J. Ellis, MD4 , Jeffrey E. Johnson, MD5 , Mark S. Myerson, MD6, Lew C. Schon, MD7,8,9,10, and David Thordarson, MD11

AbstractRecommendation: In the treatment of progressive collapsing foot deformity (PCFD), the combination of bone shape, soft tissue failure, and host factors create a complex algorithm that may confound choices for operative treatment. Realignment and balancing are primary goals. There was consensus that preservation of joint motion is preferred when possible. This choice needs to be balanced with the need for performing joint-sacrificing procedures such as fusions to obtain and maintain correction. In addition, a patient’s age and health status such as body mass index is important to consider. Although preservation of motion is important, it is secondary to a stable and properly aligned foot.Level of Evidence: Level V, consensus, expert opinion.

Keywords: adult acquired flatfoot deformity, AAFD, flatfoot, range of motion, ROM, mobility, talonavicular, fusion, progressive collapsing foot deformity, PCFD.

2 Foot & Ankle International 00(0)

Rationale

Goals of Progressive Collapsing Foot Disorder Operative Correction

Although 100% of our expert opinion panel agreed that preservation of joint motion in treatment of progressive col-lapsing foot deformity (PCFD) is a goal and 89% agreed that this standard should be especially applied to the talona-vicular (TN) joint, only 78% agreed that obesity is a predic-tor of worse outcomes. The general nature of these consensus statements points out knowledge gaps in our understanding and treatment of the disorder. The study of PCFD is relatively new. Kettelkamp and Alexander,27 in 1969, alluded to a connection between the posterior tibial tendon (PTT) and deformity of the foot. But very few papers addressed treatment in the adult prior to 1995. The early association of PTT disruption with PCFD,27 and the poten-tial causal relationship,20 may have slowed our mechanistic understanding of the interplay between malalignment and degeneration of multiple medial soft tissue structures, that would include but not be restricted to the PTT, and the over-all progression of the deformity.12 Dilwyn Evans himself suggested that his osteotomy should be applied only to chil-dren. The treatment of this diverse, multifaceted disorder is still changing and evolving.

The general goals of treatment are to relieve pain, restore alignment and mechanics, facilitate shoe fitting, and pre-vent further mechanical consequences of the progressed deformity such as joint degeneration, medial knee pain, or fibular stress fractures. These broad goals, however, do not guide us completely during the treatment process. To select a specific treatment, we need to identify the cause and loca-tion of the pain symptoms, as well as understand and man-age the mechanical disorder.31

In a symptomatic PCFD early symptoms are typically somewhat vague in nature. The premorbid mechanical con-ditions that will eventually lead to collapse, such as hind-foot valgus,10 an intrinsic altered bone morphology,2,7,34 and triceps surae contracture,14 may contribute to the nonspe-cific symptoms that can include fatigue and strain and are difficult to locate and categorize.11 With further use of WEIGHTBEARING computed tomographic, there has been additional focus placed on subluxation of the talona-vicular and subtalar joints that contributes to the forefoot abduction and hindfoot valgus deformities, respectively, that are classically seen in PCFD.1,26

Clinical and radiographic assessment help to character-ize the location of the deformity that drives operative plan-ning. This is most easily assessed with evaluation of uncoverage of the medial talar head on standing anteropos-terior view of the foot.11 The TN coverage angle35 and talar incongruency angle17 are 2 reliable and validated radio-graphic measurements used to assess severity of forefoot abduction. Both radiographic parameters provide valuable

information of the severity of forefoot abduction deformity and may guide treatment.13,17

In its simplest form, the structural mechanical goals of PCFD treatment are twofold. First, coronal plane deformity correction of the hindfoot, realigning the calcaneus colinear with the mechanical plumb line at heel strike.8 When the center of gravity of the body weight is medial to the calca-neus at heel strike phase of the gait, there will be strain on the medial soft tissue structures such as the spring and del-toid ligaments, PTT, and plantar intertarsal ligaments. Second, that same mechanical plumb line should stay in line with the second metatarsal during heel rise for the same rea-sons. This is done by correcting the forefoot abduction. During heel rise, body weight multiplied by the length of the foot creates a large vector upward and laterally if the fore-foot is not aligned with the center of gravity of the body weight.21 Similar to a valgus hindfoot, this mechanical situ-ation places significant strain on the medial plantar liga-ments. When combined with contracture of triceps surae, a significant resultant valgus strain occurs in the hindfoot of PCFD patients. Although triceps contracture is accepted in the adolescent flatfoot literature,3 it is controversial in adults. Operative treatment of equinus should be based on examina-tion of the surgeon. Note that neither of these important mechanical issues are happening in the sagittal plane and are not related to the height and collapse of the arch.

Although preservation of native joint motion and stabil-ity is a consensus goal, alignment is the highest priority. When joints are arthritic, unstable, or severely subluxed, arthrodesis may be needed.11,24 Patients tend to tolerate fusion of the TN joint, with studies demonstrating improved outcomes in pain and function with minimal complica-tion.9,18,22 However, TN fusion has been shown to result in up to 80% decrease in hindfoot motion.32 In more severe PCFD when the deformity is uncorrectable and there is degeneration in the triple joint complex, TN and ST fusion may be indicated. Studies have shown that combined TN and ST fusion in these patients results in improved pain, functional, and clinical outcomes.5

Another example is a chronically subluxated or dislo-cated subtalar joint, with the calcaneus rotating externally and translating laterally, with progressive development of impingement between the talus and calcaneus at the sinus tarsi area (sinus tarsi impingement) and finally impacting into and eroding the fibula (subfibular impingement) as a nontraumatic subtalar dislocation.16,30 The goals of stability and alignment have a higher priority than preservation of motion under these circumstances because the primary alignment goals cannot be achieved without it and there are clear signs of joint instability and degeneration.

There are other factors that affect mechanics such as obesity.19,25,37 Hindfoot arthrodesis may be more effective in achieving and maintaining correction in this patient pop-ulation.19,23,37,36 A subtalar fusion is known to impact hind-foot motion, and has been shown to decrease adjacent joint

Sangeorzan et al 3

motion as well in the talonavicular and CC.6,32,33 With greater impairment of hindfoot motion, there is a more sig-nificant risk of progressive adjacent joint degeneration in the long-term.23 Although this may have less impact in an elderly, low-demand, and/or obese patient, this option is less attractive as the primary procedure in younger, more active individuals.23

The causes of symptoms of PCFD are not scientifically established. Nearly a quarter of the population has a foot that can be defined as flat by clinical and radiographic parameters, but the vast majority of them are not symp-tomatic and will never require operative intervention.15,28,29 Many elite professional basketball players have severe arch collapse. Some of those also have a tight triceps surae mechanism that can be dramatically helpful with jumping activities. It is very possible to have a flatfoot with no symptoms if the underlying morphology does not create mechanical strain. A great deal of the orthopedic literature describes ruptured posterior tibial tendon as a cause of PCFD, but the consensus group feels it is more likely a result of the deformity.15 Multiple studies more recently have documented changes in the shape of the tarsal bones and possible changes in the slope of the posterior facet as risk factors for PCFD.2,4,7,34 It is unknown what role such things as level of activity and body weight play in the development and progression of the deformity.

In conclusion, the PCFD expert consensus group sup-ports that the collapsing foot is more than an isolated tendon dysfunction and is influenced by intrinsic morphological (bony and soft tissue) and motor factors, as well as extrinsic elements, all contributing to the development of progres-sive collapsing deformity. The general goals of treatment are to improve function and reduce pain by restoring fixed and dynamic mechanical alignment while minimizing loss of motion. Treatment should prioritize coronal plane defor-mity restoration in all phases of gait.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti-cle. ICMJE forms for all authors are available online.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685

Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042

Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445

Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998

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8. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal posi-tion of the heel following reconstruction of the stage II adult-acquired flatfoot deformity. Foot Ankle Int. 2015;36(8):919-927.

9. Crevoisier X. The isolated talonavicular arthrodesis. Foot Ankle Clin. 2011;16(1):49-59.

10. de Cesar Netto C, Kunas GC, Soukup D, Marinescu A, Ellis SJ. Correlation of clinical evaluation and radiographic hind-foot alignment in stage II adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(7):771-779.

11. Deland JT. Adult-acquired flatfoot deformity. J Am Acad Orthop Surg. 2008;16(7):399-406.

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15. Dyal CM, Feder J, Deland JT, Thompson FM. Pes planus in patients with posterior tibial tendon insufficiency: asymptom-atic versus symptomatic foot. Foot Ankle Int. 1997;18(2):85-88.

16. Ellis SJ, Deyer T, Williams BR, et al. Assessment of lateral hindfoot pain in acquired flatfoot deformity using weightbear-ing multiplanar imaging. Foot Ankle Int. 2010;31(5):361-371.

17. Ellis SJ, Yu JC, Williams BR, Lee C, Chiu YL, Deland JT. New radiographic parameters assessing forefoot abduc-tion in the adult acquired flatfoot deformity. Foot Ankle Int. 2009;30(12):1168-1176.

18. Fortin PT. Posterior tibial tendon insufficiency. Isolated fusion of the talonavicular joint. Foot Ankle Clin. 2001;6(1):137-151, vii-viii.

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19. Fuhrmann R, Trommer T, Venbrocks R. The acquired buck-ling-flatfoot. A foot deformity due to obesity? Der Orthopade. 2005;34(7):682-689.

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21. Gray EG, Basmajian JV. Electromyography and cinematog-raphy of leg and foot (“normal” and flat) during walking. Anat Rec. 1968;161(1):1-15.

22. Harper MC. Talonavicular arthrodesis for the acquired flat-foot in the adult. Clin Orthop Relat Res. 1999;365:65-68.

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