femoroacetabular impingement- current concepts and controversies review article

15
Femoroacetabular Impingement Current Concepts and Controversies Wudbhav N. Sankar, MD a, *, Travis H. Matheney, MD b , Ira Zaltz, MD c WHAT IS FEMOROACETABULAR IMPINGEMENT? The modern concept of femoroacetabular im- pingement (FAI), especially its causal relation to acetabular labral and cartilage damage, emerged following the observation that FAI can be precipi- tated by acetabular reorientation and can produce new labral damage. 1 Following this observation, in- terest in the association between chondrolabral damage and variations in femoral and acetabular anatomy has established a causal relationship between mechanical aberration in the function of the hip joint and the development of labral and cartilage damage. 2,3 The resulting modern ac- cepted definition of FAI is that it is characterized by abnormal mechanical contact between the rim of the acetabulum and the upper femur. Certain anatomic femoral or acetabular morphologies, hip-specific supraphysiologic flexion or rotational movements, repetition, and forceful motions may damage the acetabular labrum and the cartilage around the rim of the acetabulum, leading to a clin- ical syndrome of hip pain, limitation of movement, and joint damage now known as FAI. CLASSIFICATION Two distinct hip morphotypes have been des- cribed that are associated with intracapsular, me- chanical FAI. The CAM morphotype of FAI is an aspherical epiphyseal extension that produces a characteristic bump at the junction of the femoral head and femoral neck (Fig. 1). The origin is thought to be caused by an extension of the upper femoral epiphysis along the anterolateral femoral neck junction 4 ; however, the pathogenesis of this bump is not well understood and may represent a Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, 2nd Floor Wood Building, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA; b Department of Orthopaedic Surgery, Boston Children’s Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; c Department of Orthopaedic Surgery, William Beaumont Hospital, 3535 West 13 Mile Road, Royal Oaks, MI 48073, USA * Corresponding author. E-mail address: [email protected] KEYWORDS Femoroacetabular impingement CAM lesions Pincer lesions Osteoarthritis Impingement KEY POINTS Femoroacetabular impingement (FAI) is a clinical syndrome of hip pain, limitation in movement, and joint damage from abnormal mechanical contact of the acetabular rim and the proximal femur. There is a high prevalence of morphologic abnormalities associated with FAI in asymptomatic individuals. Cross-sectional and longitudinal studies support FAI playing a causative role in the development of osteoarthritis and need for total hip arthroplasty in certain patients. Surgical treatment approaches for FAI include hip arthroscopy, anterior mini-arthrotomy with/ without arthroscopic assistance, and surgical dislocation of the hip. Orthop Clin N Am 44 (2013) 575–589 http://dx.doi.org/10.1016/j.ocl.2013.07.003 0030-5898/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved. orthopedic.theclinics.com

Upload: hgvader

Post on 26-Nov-2015

80 views

Category:

Documents


3 download

TRANSCRIPT

  • FemoroacetabularImpingementCurrent Concepts and Controversies

    Wudbhav N. Sankar, MDa,*, Travis H. Matheney, MDb,Ira Zaltz, MDc

    The modern concept of femoroacetabular im-pingement (FAI), especially its causal relation toacetabular labral and cartilage damage, emergedfollowing the observation that FAI can be precipi-tated by acetabular reorientation and can producenew labral damage.1 Following this observation, in-terest in the association between chondrolabraldamage and variations in femoral and acetabularanatomy has established a causal relationshipbetween mechanical aberration in the function ofthe hip joint and the development of labral andcartilage damage.2,3 The resulting modern ac-cepted definition of FAI is that it is characterizedby abnormal mechanical contact between the rimof the acetabulum and the upper femur. Certainanatomic femoral or acetabular morphologies,

    damage the acetabular labrum and the cartilagearound the rim of the acetabulum, leading to a clin-ical syndrome of hip pain, limitation of movement,and joint damage now known as FAI.

    CLASSIFICATION

    Two distinct hip morphotypes have been des-cribed that are associated with intracapsular, me-chanical FAI. The CAM morphotype of FAI is anaspherical epiphyseal extension that produces acharacteristic bump at the junction of the femoralhead and femoral neck (Fig. 1). The origin isthought to be caused by an extension of the upperfemoral epiphysis along the anterolateral femoralneck junction4; however, the pathogenesis of thisbump is not well understood and may represent

    P

    l syt o

    no

    t FAin

    hislo

    oped

    ic.th

    eclinics

    .comOrthop Clin N Am 44 (2013) 575589 ha Division of Orthopaedic Surgery, The Childrens Hospital of Philadelphia, 2nd Floor Wood Building, 34th andCivic Center Boulevard, Philadelphia, PA 19104, USA; b Department of Orthopaedic Surgery, Boston ChildrensHospital, 300 Longwood Avenue, Boston, MA 02115, USA; c Department of Orthopaedic Surgery, WilliamBeaumont Hospital, 3535 West 13 Mile Road, Royal Oaks, MI 48073, USA* Corresponding author.E-mail address: [email protected] IS FEMOROACETABULARIMPINGEMENT?

    hip-specific supraphysiologic flexion or rotationalmovements, repetition, and forceful motions mayKEYWORDS

    Femoroacetabular impingement CAM lesions

    KEY POINTS

    Femoroacetabular impingement (FAI) is a clinicajoint damage from abnormal mechanical contac

    There is a high prevalence of morphologic abindividuals.

    Cross-sectional and longitudinal studies supporosteoarthritis and need for total hip arthroplasty

    Surgical treatment approaches for FAI includewithout arthroscopic assistance, and surgical dhttp://dx.doi.org/10.1016/j.ocl.2013.07.0030030-5898/13/$ see front matter 2013 Elsevier Inc. Allincer lesions Osteoarthritis Impingement

    ndrome of hip pain, limitation in movement, andf the acetabular rim and the proximal femur.

    rmalities associated with FAI in asymptomatic

    I playing a causative role in the development ofcertain patients.

    ip arthroscopy, anterior mini-arthrotomy with/cation of the hip.rights reserved. ort

  • Sankar et al576a distinct type of upper femoral chondroepiphy-seal maturation.5 Because the size, location, andextension of the deformity are unique for eachhip, the ability to visualize the prominence using

    Fig. 1. Lateral view of the hip shows the typicalappearance and location of a CAM lesion. As the hipcomes into flexion and internal rotation, this promi-nence can abut the acetabular rim and labrum,causing impingement.plain radiographs is variable. Frog-lateral, cross-table lateral, or Dunn-lateral views may be used;however, the reliability depends on the locationof the deformity and the rotation of the limb duringthe radiograph. Because of this variability, radialmagnetic resonance imaging (MRI) reconstruc-tions are often used to more accurately assessthe morphology of the head-neck junction andminimize the chance of missing CAM lesions(Fig. 2). On either plain radiographs or radial se-quences, the severity of deformity can be charac-terized by the alpha angle of Notzli.6 The alphaangle estimates the degree at which the radius ofcurvature of the femoral head begins to increase.Thus, larger alpha angle measurements indicatea more aspherical femoral head.Acetabular-sided deformity or pincer impinge-

    ment includes global overcoverage, focal over-coverage, and retroversion of the acetabulum,and results in premature contact between thefemoral neck and acetabular rim when the hip isflexed (Fig. 3). These features are recognizableradiographically using an anteroposterior (AP)pelvis radiograph. The coverage of the acetabulumrelative to the femoral head is traditionally as-sessed using the lateral center-edge angle (LCE).There is general agreement that a normal LCE isbetween 25 and 35 and that hips with an LCEgreater than 40 are at risk for impingement inflexion. Focal overcoverage can be assessedusing the crossover sign that is observed when

    Fig. 2. Image from a radial sequence MRI showingreduced offset at the femoral head-neck junction.The degree of asphericity can be quantified usingthe alpha angle of Notzli.6 A best-fit circle is firstdrawn around the femoral head. The alpha angle isthe angle formed between a line drawn down theaxis of the femoral neck and a line drawn to the pointat which the contour of the femoral head-neck junc-tion deviates from the perfect circle. The larger thealpha angle, the greater the degree of asphericity.the anterior acetabular wall crosses over the pos-terior acetabular wall on a properly oriented APpelvis radiograph (Fig. 4). There is conflicting infor-mation regarding the sensitivity of the crossoversign. Although the crossover sign may representtrue focal acetabular overcoverage in some cases,in others it may be artifactually caused by theorientation of the anterior inferior iliac spine.79 Inaddition, when a crossover sign is accompaniedby a posterior wall sign, which occurs when theposterior wall of the acetabulum is located medialto the center of the femoral head, the acetabulummay be retroverted and the posterosuperiorfemoral coverage may be insufficient. A crossoversign accompanied by a posterior wall sign may beassociated with anterior impingement when thehip is flexed and posterosuperior instability whenthe hip is in extension.10

    Many hips are thought to have features of bothCAM-type femoral morphology and acetabularovercoverage, resulting in so-called mixed-typeimpingement.

    PATHOPHYSIOLOGY

    The mechanics of impingement limit the degree ofsagittal plane hip motion, diminishing the degree

  • to which an affected individual is able to squat.11

    Normal mechanical gait parameters are alteredin patients affected by CAM-type FAI, withdemonstrated decrease in hip abduction and fron-tal plane motion compared with control hips.12

    Chegini and colleagues13 used computationalmodels to analyze stresses along the acetabularrim in simulated dysplastic and impinging joints.Impingement was modeled by increasing thealpha angle and the acetabular depth using a

    Fig. 3. Pincer morphology from an excessively deep hip socket. With motion, the femoral head-neck junction pre-maturely abuts the edge of the deep acetabulum, causing primary injury to the labrum and peripheral articularcartilage. This impingement can also cause levering of the femoral head away from the joint, resulting in poste-rior shear and contrecoup chondrolabral lesions.

    Femoroacetabular Impingement 577Fig. 4. Radiographic signs suggesting acetabular retroverscrossover sign is formed when the anterior acetabular walrior wall sign is formed when the edge of the posterior wpresence of both signs on a properly oriented AP pelvic rion, which can be a cause of pincer impingement. Thel crosses over the posterior acetabular wall. The poste-all lies medial to the center of the femoral head. Theadiograph suggests acetabular retroversion.

  • thought to be related to remodeling caused by

    motion may confound the physical examination.Range of motion is usually limited in hips that aremorphologically prone to symptomatic FAI, withaverage flexion reportedly slightly greater than90. The classic provocative maneuver is the ante-rior impingement test, which is pain elicited byflexion, adduction, and internal rotation of theaffected hip (Fig. 5). Other provocative tests in-clude the resisted straight-leg raise and the poste-rior impingement test. Clinical symptoms andphysical examination signs must be correlatedwith radiographic data to firmly establish the diag-nosis of FAI.

    PREVALENCE OF DISEASE

    The prevalence of clinically significant FAI remainsunknown. The reported prevalence of FAI varieswidely depending on the parameters used to

    Sankar et al578chronic and repetitive contact between theacetabular rim and femoral neck. The labrum istherefore crushed between the bony acetabularrim and femoral neck and the peripheral-mostacetabular cartilage may become detached andfrayed. In addition, contrecoup chondrolabral le-sions in the posterior acetabulum, thought toresult from anterior levering of the femur causingposterior shear, have been observed clinically.2

    The two major differences between CAM-typeand pincer-type injury patterns are the increaseddepth of chondral injury associated with the CAMmechanism, and confinement of damage to therim and peripheral acetabulum in pincer-typeimpingement.

    CLINICAL PRESENTATION

    The presentation of patients with symptomaticanterior FAI has been described by multiple inves-tigators.1719 Patients usually present withinsidious-onset pain about the hip that is charac-teristically localized to the groin but may be expe-rienced in the buttock, lower back, trochantericregion, or the anterior thigh and knee. Pain maybe precipitated by athletic activity or activitiesthat require flexion, such as crouching or sitting.The pain pattern often goes unrecognized by pri-mary physicians, leading to missed diagnosis ormisdirected treatment.19 Because the symptomscaused by FAI are not disease specific, carefulpatient history is essential when entertaining thediagnosis of FAI.The physical examination of a patient with

    symptomatic FAI is characterized by painful limita-tion of hip flexion. In patients with highly irritablestanding-to-sitting motion and was shown tocause distortion and shearing at the bone-tissueinterface, a calculated conclusion that is consis-tent with damage observed clinically in impingingjoints at the time of surgery.13 These mechanicalstudies support theories developed by observingpatterns of chondral injury at the time of surgicaltreatment.2

    CAM-type impingement, in which an asphericalbump enters the acetabular fossa during flexion,causes labral distortion and shear forces withinthe peripheral acetabulum that can cause det-achment of the labrum from the rim of the ace-tabulum and full-thickness or partial-thicknessdelamination injuries of the hyaline cartilagewithin the joint.2,3,1416 In contrast, the damagepattern in hips with pincer-type mechanics ismore peripheral. These hips often have a charac-teristic trough located in the femoral neck,hip joints, hip guarding and compensatory lumbardefine the condition. Ochoa and colleagues20

    reviewed 155 patients with a mean age of 32 years(range, 1850 years) who presented to primarycare or orthopedic clinics with a chief complaintof hip pain. Based on radiographic signs of FAI(herniation pits, pistol grip deformity, crossoversign, center-edge angle >39, and/or alphaangle >50), the investigators reported that 87%of the patients had at least 1 finding consistentwith FAI, and 81% had at least 2 findings.However, several recent studies have estab-

    lished a high prevalence of morphologic abnor-malities associated with FAI in asymptomaticindividuals as well:

    Reichenbach and colleagues21 reported on1,080 asymptomatic military recruits in Su-miswald, Switzerland, of whom 430 were

    Fig. 5. The impingement test. The test is consideredpositive if pain is elicited by flexion, adduction, and

    internal rotation of the affected hip.

  • TorcoThFAThph

    determine whether a symptomatic patient is sym-ptomatic because of FAI.

    CAUSATIVE ROLE IN OSTEOARTHRITIS

    The contemporary theory of FAI as a causativefactor in the development of osteoarthritis hasbeen championed by Ganz and colleagues,25

    and holds that the morphologic abnormalities ofthe femoral head and/or acetabulum result inabnormal contact between the femoral neck/head and the acetabular margin. This abnormalcontact leads to supraphysiologic stress causingtearing of the labrum and avulsion of the underly-ing cartilage region (Fig. 6).26,27 The continuedabnormal contact results in further deteriorationand wear of the articular cartilage, with eventualonseto wthritiscongarthr

    Femoroacetabular Impingement 579a-angles. Women

  • stuthemeis

    thritis within 5 years compared to a less

    Recent evidence also suggests that FAImorphology may result from early exposure to

    TREA

    Treatdecarecogthatof ne

    Sankar et al580decreased internal rotation 20 had a53% risk of developing end-stage osteoar-thritis within 5 years.

    The Chingford cohort provides anotherrecent longitudinal study of the relationshipbetween hip morphology and the develop-ment of osteoarthritis.30 1003 healthy femalesubjects were enrolled after undergoing abaseline AP radiograph of the pelvis, whichwas measured the presence of CAM and pin-cer deformity. At 19 year follow-up, these ra-diographs were repeated. Of those patientswho went on to THA, the baseline hipmorphology was compared to a randomthan 2% risk of end-stage osteoarthritis inhips with an a-angle less than 83 (odds ra-tio of 9.7 adjusted for age, sex, BMI andbaseline Kellgren-Lawrence grade).

    Hips with both an a-angle >83 and Based on this criterion, the investigatorsreported a 5.5% risk of developing osteo-arthritis in the contralateral non-osteoar-thritic hip compared to a 3% risk in thecontrol group.

    A pistol grip deformity conferred an 8.3%risk of developing osteoarthritis in the con-tralateral non-osteoarthritic hip comparedto a 3.6% risk in the control group.

    Both factors were strongly and significantlyassociated with an increased risk of devel-oping hip osteoarthritis after adjusting forage, body mass index, and gender.

    In addition to this representative cross-sectionaldy, longitudinal studies of FAI have establishedtemporal relationship of cause to effect, byasuring proximal femoral morphology before italtered by osteoarthritis:

    A prospective study of FAI in the Cohort Hipand Cohort Knee (CHECK) study reportedon a Dutch national sample of 723 patientspresenting for the first time with recent onsetof hip or knee pain.29 Initial AP pelvic radio-graphs were measured to determine thea-angle, and subjects were followed for 5years to determine the risk of developingend-stage osteoarthritis. Ages ranged 45 to 65 years 80% of the cohort was female Subjects had no osteoarthritis at baselinewith either a Kellgren-Lawrence osteoar-thritic grade of 0 (76%) or grade 1 (24%).

    Hips with a baseline AP a-angle >83 had a25% risk of developing end-stage osteoar-sample of 243 hips that did not require THA. ximaTMENT

    ment of FAI has evolved greatly over the pastde, in large part because of an increasednition of the different morphologic factorscontribute to FAI as well as the developmentw surgical techniques for reshaping the pro-high-impact sports, and may therefore be devel-opmental in origin rather than a reaction to thearthritic process. Kapron and colleagues31 re-ported that 95% of 134 hips in collegiate footballplayers had at least one radiographic sign ofCAM or pincer impingement, which exceeds thereported prevalence in asymptomatic membersof the general population. Siebenrock and col-leagues32 showed a 10-fold increase in the preva-lence of CAM morphology in a cohort of elitebasketball players compared with nonactive age-matched controls. In addition, the investigatorsshowed increasing alpha angles in the athletesduring skeletal maturation, and suggested thatrepeated high-stress activities during childhoodmay modulate growth of the proximal femurtoward an abnormal shape via subclinical physealinjury.Based on the previously mentioned studies in

    which FAI morphology was studied before thepresence of radiographic osteoarthritis and theprevalence studies in young, asymptomatic per-sons it is clear that FAI, and its morphologic riskfactors, are common in young adult hips and pre-disposes to the later development of osteoarthritisin certain patients. Longitudinal studies also sup-port that, in both men and women aged 45 to 65years, the presence of CAM deformities at base-line substantially increases the risk of developingosteoarthritis and the need for a THA. However,in most hips the presence of a CAM lesion is notsufficient in isolation to lead to the developmentof clinically significant and symptomatic osteoar-thritis. At this point, there is insufficient evidencefrom longitudinal population studies to confirm asimilar association between the presence of apincer deformity and the development of clinicalor radiographic osteoarthritis. Ages ranged 44 to 67 years Median AP a-angle in those who requiredTHA was 62.4 at baseline compared to45.8 in controls (P 5 .001).

    The odds ratio of needing a THA increased1.05 for each 1 increase in initial a-angle.l femur and acetabular rim.27

  • The successful treatment of FAI demands:

    Accurate diagnosis. Is the pain caused byFAI, a nonarticular cause, or both? A clear understanding of the possible path-omorphologies that can lead to arthrosis

    A concomitant understanding of otherpossible causes of hip pain and arthrosis(eg, soft tissue impingement/inflammation,concomitant developmental dysplasia ofthe hip)

    Assessment of patient-based factors Age

    proaches, arthroscopy, or a combination of

    which a joint-preserving procedure is notind

    SU

    Sintionova

    become safe to gain access to the hip joint withoutconcern for avascular necrosis. This ability has laidthe groundwork for the expansion in surgical treat-ment options for FAI. As previously noted, the firstcritical step is the accurate diagnosis of the causeof pain and arthrosis. Following this, a thoroughunderstanding of the three-dimensional anatomyof the hip and the surgical techniques availableto address its pathomorphology are paramountto ensure that any procedure remains safe aswell as being efficacious.In general, there are 3 surgical techniques

    labrum, femoral neck, joint capsule, iliop-

    visu

    Femoroacetabular Impingement 581Fig. 7. (A) Intraoperative appearance of a CAM lesion

    traicated.

    RGICAL MANAGEMENT

    ce the initial description of his surgical disloca-n approach to the hip, Ganz and colleagues33

    ted that, with improved familiarity with thescular anatomy of the proximal femur, it hasthe two?

    NONOPERATIVE MANAGEMENT

    Because of the high prevalence of FAI morphologyin asymptomatic hips, conservative managementis usually warranted as an initial step, dependingon the patient and the clinical picture.24,31 Modal-ities including physical therapy to alleviate symp-toms associated with periarticular causes,antiinflammatories, and activity/lifestyle modifica-tion can all be used. Medical and/or conservativemanagement may also be of particular benefitwhen there is evidence of advanced arthrosis for Demands. Can patients change their livesto mitigate their symptoms?

    Expectations Knowledge of the surgeons surgical skill set:can clinicians gain adequate access toaddress all disorders through open ap-operative view of femoral head-neck osteoplasty showsoas, and the inferior portion of anterior infe-rior iliac spine

    Surgical Dislocation

    Technique: performed through a lateralGibson approach to the hip with a digastrictrochanteric osteotomy and anterior-basedarthrotomy. Once all portions of the hipjoint are exposed, acetabular lesions areaddressed, including rim resection, labralrepair, acetabular chondroplasty, followedby femoral osteochondroplasty as needed(Fig. 7). The capsule is repaired and thetrochanteric fragment reattached withscrews. Some surgeons favor postoperative

    alized through a surgical dislocation approach. (B) In-currently used to treat FAI pathomorphology: sur-gical dislocation of the hip; anterior mini arthrot-omy, with or without arthroscopic assistance;and arthroscopy. For the purposes of discussingand comparing these techniques, the followingterminology is used to describe the regions aroundthe hip joint:

    Central compartment: the area within theacetabulum, including the cotyloid notch,articular surface of the acetabulum, and liga-mentum teres

    Peripheral compartment: the area outside theacetabulum, including the acetabular rim,s improved contour and restoration of offset.

  • abduction precautions. Such precautions aremost likely not necessary because it is adigastric osteotomy and under compressionin abduction. However, it may be more sus-ceptible to rotational forces and thereforehip-strengthening exercises may need to belimited until there is trochanteric union.

    Regions accessible within the hip: centraland complete peripheral compartment.

    Pros: complete visualization and access toboth the acetabulum and femoral head,especially beneficial for treating posterioracetabular rim and posterior hip joint lesions.Allows easy repair of the joint capsule, whichmay be of benefit in preventing later hip

    whomay be comfortable with arthroscopy forchondral debridement but not osteochondro-plasty, rim resection, or labral repair throughthe arthroscope. Proponents of arthrotomyalone think that they can attain adequate ac-cess to the anterior acetabular rim, labrum,and femoral neck.

    Cons: treatment of acetabular rim lesionswith rim resection and labral repair is difficult.There is also incomplete access and visuali-zation of the posterior hip joint and acetab-ular rim.

    Arthroscopy

    men

    Sankar et al582instability. Cons: more invasive surgery, longer courseof recovery, and potential for trochantericnonunion and painful screws.

    Anterior Mini Arthrotomy, With or WithoutArthroscopic Assistance

    Technique: when used, arthroscopy is typi-cally performed first under traction to assessthe central compartment and performchondroplasty and labral debridement asneeded. This step is followed by an anteriorarthrotomy performed through a standardanterior approach to perform the femoral os-teochondroplasty and possibly labraldebridement and limited acetabular rimresection.

    Regions accessible within the hip: central(limited central with arthrotomy alone) andlimited peripheral compartment.

    Pros: less soft tissue dissection and no os-teotomy but still able to visualize the centralcompartment to treat chondral injuries (witharthroscopy) as well as providing access totreat CAM lesions. Beneficial for the surgeon

    Fig. 8. (A) Arthroscopic view of the peripheral compart

    tion from CAM-type FAI. (B) Arthroscopic view after femo Technique: typically performed with the pa-tient either supine or in a lateral position anda combination of portals including the peritro-chanteric, midanterior, and anterior. Tractionis used while assessing the central compart-ment, then released to perform femoral osteo-chondroplasty and assess range of motion/adequacy of femoral neck resection (Fig. 8).

    Regions accessible within the hip: centraland limited peripheral compartment (poor ac-cess to posterior regions of the hip joint andacetabular rim).

    Pros: potentially the smallest amount of sur-gical dissection of superficial tissues and notrochanteric osteotomy. Without trochantericosteotomy, patients can be mobilized withphysical therapy more aggressively withoutconcern for affecting osteotomy healing.

    Cons: to properly address all possible le-sions within the hip with FAI morphology de-mands an advanced arthroscopic skill setthat allows the surgeon to correct acetabularrim lesions and perform labral repair andfemoral osteochondroplasty. In addition,there is increasing emphasis on the abilityto perform a capsular repair.

    t shows prominence and injury of the head-neck junc-

    ral head-neck osteochondroplasty.

  • Femoroacetabular Impingement 583OUTCOMES

    The outcome of the surgical treatment of FAI is var-iable. Patient-related factors such as lifestyle, workand sport demands, patient expectations, andduration of symptoms can all play a role.2,27,3455

    Most studies reporting surgical outcome aresingle-surgeon experience, use a variety ofoutcome instruments, include mixed patient popu-lations with variable types of impingement (CAM,pincer, both), use a variety of methods to describethe deformity, span a range of surgical experience,and have short-term (minimum 1 year) to midterm(average 56 year) follow-up (Table 1). Becausethe presentation can vary substantially, when thisis combined with surgeon-related and surgery-related variables, the accurate determination ofoutcomes is difficult.

    Nonoperative Management

    Few outcome data exist for the nonoperativemanagement of FAI. One investigator advocatedan initial trial of conservative therapy and activitymodification in symptomatic patients with prear-thritic intra-articular hip disorder, stating that, pro-vided there are ongoing follow-up evaluations,many patients may opt for continued conservativetherapy.40 In these cases and in the asymptomaticpatient, continued close follow-up is criticalbecause the rate of progression to advancedarthrosis is unpredictable and may lead to aninability to keep hip-preserving surgery as a viableoption.56

    Surgical Dislocation

    Since its initial description by Ganz and col-leagues,33 surgical dislocation has remained thegold standard treatment of FAI. It has been usedto treat a broad spectrum of deformity, across awide spectrum of ages and causes (Fig. 9).Matsuda and colleagues44 performed a system-atic review of reported outcomes and, in general,short-term to mid-term results are good to excel-lent with few complications. Reported successrates across different studies ranged from 65%to 94%, whereas complication rates ranged from0% to 20%, primarily from trochanteric nonunion.The conversion to THA as an end point for failurehas been reported to be 0% to 30%.46,49,55

    Studies reporting higher rates of conversion toTHA were earlier reports and in these initial patientcohorts the best indications for surgery had notbeen elucidated. These studies included older pa-tients with more advanced arthrosis and concur-rent dysplasia.36,46 An argument can be made

    that more recent literature reflects outcomesfollowing refinement of surgical indication andtechnique in which the THA conversion rate isonly 0% to 5%.35,38,44,48

    Anterior Mini Arthrotomy, With or WithoutArthroscopic Assistance

    In groups that accessed the hip joint primarily viaan anterior arthrotomy, with or without arthro-scopic assistance, outcomes were similar to thoseobtained in the more recent surgical dislocationgroup (71%92% success rate).42,53,5759 How-ever, the incision lengths described for the miniopen ranged from 2 to 12 cm. In the 4 reports citedby Matsuda and colleagues,44 the complicationrates ranged from 0% to 17% and includedseveral inadequate resections requiring revisionosteoplasty and/or labral fixation, transient lateralfemoral cutaneous nerve injuries, and 1 femoralneck fracture treated nonoperatively.

    Arthroscopy

    With the advent of improved technique, severalstudies have evaluated the use of arthroscopy totreat FAI morphology rather than just labraldebridement, the most commonly previouslyperformed arthroscopic hip procedure. The pub-lished success rate ranged from 67% to90%.34,38,39,41,43,50,51,54,58,6064 Most of thesestudies were short-term follow-up (12 years onaverage) and showed a conversion rate to THAof 0% to 9%. Complication rates were the lowestof the 3 surgical groups, ranging from 0% to 5%,with less frequent pudendal or lateral femoral cuta-neous nerve palsy and (given the number ofdescribed cases in some series of more than1000 arthroscopies) few reported revisions. Aprominent point brought out in the current litera-ture is that the learning curve for arthroscopictreatment is not well defined and may have animportant effect on the individual surgeons out-comes. Because most of these series weresingle-surgeon reports, the results may not betransferrable.

    FUTURE DIRECTIONS

    FAI as a clinical entity is in its infancy and under-standing of the condition will undoubtedly increasein the years to come. Areas in need of further studyinclude the natural history of FAI morphology,particularly pincer deformities, and other potenti-ating factors that explain why certain people withFAI become symptomatic and others do not.With regard to the deformity, more knowledge isneeded about the importance of normal structures

    around the hip in the course of treating the more

  • Table 1Selected outcome studies for FAI

    Study No. Hips Mean FU (y) Type of FAI Outcome Measure Outcomes Failures Predictors of Failure

    Non-Operative Treatment

    Huntet al,40 2012

    58 1 Mixed Satisfaction, need forsurgery, others

    44% satisfied 56% eventuallychose surgery

    Desire for moreactive lifestyle

    Surgical Dislocation

    Beauleet al,35 2007

    37 3.1 CAM WOMAC, UCLA,SF-12

    [ 20.2 pts[ 2.7 pts

    16% dissatisfied Advanced arthrosis

    Beck et al,36 2004 19 4.7 CAM Merle dAubigne 68% good toexcellent

    26% Advanced (>Tonnis 1)arthrosis

    Espinosaet al,18 2006

    60 2 Pincer CAM Merle dAubigne,Tonnis grade ofarthrosis

    76% good toexcellent withlabraldebridement; 94%with labralrefixation

    4% with labraldebridement

    Results significantlybetter after rimtrim withrefixation oflabrum vsdebridement alone

    Murphyet al,46 2004

    23 5.2 Mixed Conversion to THA NR 30% convertedto THA

    Advanced arthrosisor combinedimpingement andinstability

    Peterset al,49 2010

    96 2.2 Mixed mHHS [ 24 pts 6% convertedto THA

    Advanced arthrosis

    Yunet al,55 2009

    15 >1 Mixed mHHS [ 17 pts 0% NR

    Anterior arthrotomy ArthroscopyLaudeet al,58 2009

    100 4.9 CAM NAHS [ 29.1 pts 11% convertedto THA

    NR

    Lincolnet al,43 2009

    16 2 CAM mHHS [ 12.3 pts 6% NR

    Sankaretal

    584

  • Neppleet al,59 2009

    Arthroscopy(grp 1) vsarthroscopywith osteoplasty(Grp 2)

    Grp 1: 36Grp 2: 39

    2.31.7

    CAM mHHS 74%92% Good toExcellent; trendtoward higher HHSin Group 2

    Grp 1: 26%Grp 2: 4%

    NR

    Ribaset al,53 2007

    35 2.4 CAM Merle dAubigne [ 3.1 pts 3% Advanced(Tonnis 2)arthrosis

    Arthroscopy

    Ilizaliturriet al,41 2008

    19 2.4 CAM Clinical 84% reportedimprovedsymptoms

    16% deteriorated NR

    Philipponet al,50 2009

    112 2.3 Mixed SatisfactionmHHS

    Median 9/10[ 26 pts

    9% convertedto THA

    Increased age;decreased pre-opHarris Hip Score;minimum jointspace

  • Sankar et al586obvious disorders (eg, an intact labrum, impor-tance of the ligamentum teres, capsular repair).In addition, the development of a comprehensivegrading system for FAI would lay the foundationfor comparative studies. In terms of treatment,longer follow-up studies with standardizedoutcome measures are necessary to determinethe optimal treatment of particular patterns ofdisease.

    Fig. 9. (A) AP and (B) lateral view of the right hip showing a(C, D) AP and lateral view after osteochondroplasty was perthe improvement in the head-neck contour and the screwREFERENCES

    1. Myers SR, Eijer H, Ganz R. Anterior femoroacetab-

    ular impingement after periacetabular osteotomy.

    Clin Orthop Relat Res 1999;363:939.

    2. Beck M, Kalhor M, Leunig M, et al. Hip morphology

    influences the pattern of damage to the acetabular

    cartilage: femoroacetabular impingement as a

    cause of early osteoarthritis of the hip. J Bone Joint

    Surg Br 2005;87(7):10128.

    typical CAM lesion at the femoral head-neck junction.formed via an open surgical dislocation approach. Notes used to repair the trochanteric osteotomy.

  • Femoroacetabular Impingement 5873. Pfirrmann CW, Mengiardi B, Dora C, et al. Cam and

    pincer femoroacetabular impingement: character-

    istic MR arthrographic findings in 50 patients. Radi-

    ology 2006;240:77885.

    4. Siebenrock KA, Wahab KH, Werlen S, et al.

    Abnormal extension of the femoral head epiphysis

    as a cause of cam impingement. Clin Orthop Relat

    Res 2004;(418):5460.

    5. Serrat MA, Reno PL, McCollum MA, et al. Variation

    in mammalian proximal femoral development:

    comparative analysis of two distinct ossification

    patterns. J Anat 2007;210:24958.

    6. Notzli HP, Wyss TF, Sotecklin CH. The contour of

    the femoral head-neck junction as a predictor for

    the risk of anterior impingement. J Bone Joint

    Surg Br 2002;84:55660.

    7. Zaltz I, Kelly BT, Hestroni I, et al. The crossover

    sign overestimates acetabular retroversion. Clin

    Orthop Relat Res 2012;471(8):246370.

    8. Jamali AA, Mladenov K, Meyer DC, et al. Antero-

    posterior pelvic radiographs to assess acetabular

    retroversion: high validity of the cross-over-sign.

    J Orthop Res 2007;25:75865.

    9. Ezoe M, Naito M, Inoue T. Prevalence of acetabular

    retroversion among various disorders of the hip.

    J Bone Joint Surg Am 2006;88:3729.

    10. Dandachli W, Islam SU, Liu M, et al. Three-dimen-

    sional CTanalysis to determine acetabular retrover-

    sion and the implications for the management of

    femoro-acetabular impingement. J Bone Joint

    Surg Br 2009;91:10316.

    11. Lamontagne M, Kennedy MJ, Beaule PE. The ef-

    fect of cam FAI on hip and pelvic motion during

    maximum squat. Clin Orthop Relat Res 2009;467:

    64550.

    12. Kennedy MJ, Lamontagne M, Beaule PE. Femoroa-

    cetabular impingement alters hip and pelvic

    biomechanics during gait walking biomechanics

    of FAI. Gait Posture 2009;30:414.

    13. Chegini S, Beck M, Ferguson SJ. The effects of

    impingement and dysplasia on stress distribu-

    tions in the hip joint during sitting and walking:

    a finite element analysis. J Orthop Res 2009;27:

    195201.

    14. Ito K, Leunig M, Ganz R. Histopathologic features

    of the acetabular labrum in femoroacetabular

    impingement. Clin Orthop Relat Res 2004;429:

    26271.

    15. Leunig M, Podeszwa D, Beck M, et al. Magnetic

    resonance arthrography of labral disorders in

    hips with dysplasia and impingement. Clin Orthop

    Relat Res 2004;(418):7480.

    16. Anderson LA, Peters CL, Park BB, et al. Acetabular

    cartilage delamination in femoroacetabular

    impingement. Risk factors and magnetic reso-

    nance imaging diagnosis. J Bone Joint Surg Am2009;91(2):30513.17. Beck M, Leunig M, Clarke E, et al. Femoroacetab-

    ular impingement as a factor in the development of

    nonunion of the femoral neck: a report of three

    cases. J Orthop Trauma 2004;18(7):42530.

    18. Espinosa N, Rothenfluh DA, Beck M, et al. Treat-

    ment of femoro-acetabular impingement: prelimi-

    nary results of labral refixation. J Bone Joint Surg

    Am 2006;88(5):92535.

    19. Clohisy JC, Knaus ER, Hunt DM, et al. Clinical pre-

    sentation of patients with symptomatic anterior hip

    impingement. Clin Orthop Relat Res 2009;467(3):

    63844.

    20. Ochoa LM, Dawson L, Patzkowski JC, et al. Radio-

    graphic prevalence of femoroacetabular impinge-

    ment in a young population with hip complaints is

    high. Clin Orthop Relat Res 2010;468:27104.

    21. Reichenbach S, Juni P, Werlen S, et al. Prevalence

    of cam-type deformity on hip magnetic resonance

    imaging in young males: a cross-sectional study.

    Arthritis Care Res 2010;62:131927.

    22. Jung KA, Restrepo C, Hellman M, et al. The preva-

    lence of cam-type femoroacetabular deformity in

    asymptomatic adults. J Bone Joint Surg Br 2011;

    93B:13037.

    23. Gosvig KK, Jacobsen S, Palm H, et al. A new radio-

    logical index for assessing asphericity of the

    femoral head in cam impingement. J Bone Joint

    Surg Br 2007;89B:130916.

    24. Hack K, Di Primio G, Rakhra K, et al. Prevalence of

    cam-type femoroacetabular impingement mor-

    phology in asymptomatic volunteers. J Bone Joint

    Surg Am 2010;92(14):243644.

    25. Ganz R, Parvizi J, Beck M, et al. Femoroacetabular

    impingement: a cause of early osteoarthritis of the

    hip. Clin Orthop Relat Res 2003;417:11220.

    26. Parvizi J, Leunig M, Reinhold G. Femoroacetabu-

    lar impingement. J Am Acad Orthop Surg 2007;

    9:56170.

    27. Ganz R, Leunig M, Leunig-Ganz K, et al. The etiol-

    ogy of osteoarthritis of the hip: an integrated

    mechanical concept. Clin Orthop Relat Res 2008;

    466(2):26472.

    28. Doherty M, Courtney P, Doherty S, et al. Nonspher-

    ical femoral head shape (pistol grip deformity),

    neck shaft angle, and risk of hip osteoarthritis.

    Arthritis Rheum 2008;58(10):317282.

    29. Agricola R, Heijboer MP, Bierma-Zeinstra SM, et al.

    Cam impingement causes osteoarthritis of the hip:

    a nationwide prospective cohort study (CHECK).

    Ann Rheum Dis 2013;72(6):91823.

    30. Nicholls AS, Kiran A, Pollard TC, et al. The associ-

    ation between hip morphology parameters and

    nineteen-year risk of end-stage osteoarthritis of

    the hip: a nested case-control study. Arthritis

    Rheum 2011;63(11):3392400.

    31. KapronAL,AndersonAI, Aoki SK, et al. Radiographicprevalence of femoroacetabular impingement in

  • Sankar et al588collegiate football players: AAOS Exhibit Selection.

    J Bone Joint Surg Am 2011;93(19): e111(110).

    32. Siebenrock KA, Ferner F, Noble PC, et al. The cam-

    type deformity of the proximal femur arises in child-

    hood in response to vigorous sporting activity. Clin

    Orthop Relat Res 2011;469:322940.

    33. Ganz R, Gill TJ, Gautier E, et al. Surgical disloca-

    tion of the adult hip a technique with full access

    to the femoral head and acetabulum without the

    risk of avascular necrosis. J Bone Joint Surg Br

    2001;83(8):111924.

    34. Bardakos NV, Vasconcelos JC, Villar RN. Early

    outcome of hip arthroscopy for femoroacetabular

    impingement: the role of femoral osteoplasty in

    symptomatic improvement. J Bone Joint Surg Br

    2008;90(12):15705.

    35. Beaule PE, Le Duff MJ, Zaragoza E. Quality of life

    following femoral head-neck osteochondroplasty

    for femoroacetabular impingement. J Bone Joint

    Surg Am 2007;89(4):7739.

    36. Beck M, Leunig M, Parvizi J, et al. Anterior femo-

    roacetabular impingement: part II. Midterm results

    of surgical treatment. Clin Orthop Relat Res

    2004;(418):6773.

    37. Bedi A, Zaltz I, De La Torre K, et al. Radiographic

    comparison of surgical hip dislocation and hip

    arthroscopy for treatment of cam deformity in fem-

    oroacetabular impingement. Am J Sports Med

    2011;39(Suppl):20S8S.

    38. Espinosa N, Beck M, Rothenfluh DA, et al. Treat-

    ment of femoro-acetabular impingement: prelimi-

    nary results of labral refixation. Surgical

    technique. J Bone Joint Surg Am 2007;89(Suppl

    2 Pt.1):3653.

    39. Fabricant PD, Heyworth BE, Kelly BT. Hip arthros-

    copy improves symptoms associated with FAI in

    selected adolescent athletes. Clin Orthop Relat

    Res 2012;470(1):2619.

    40. Hunt D, Prather H, Harris Hayes M, et al. Clinical

    outcomes analysis of conservative and surgical

    treatment of patients with clinical indications of pre-

    arthritic, intra-articular hip disorders. PM R 2012;

    4(7):47987.

    41. Ilizaliturri VM Jr, Orozco-Rodriguez L, Acosta-

    Rodriguez E, et al. Arthroscopic treatment of

    cam-type femoroacetabular impingement: prelimi-

    nary report at 2 years minimum follow-up.

    J Arthroplasty 2008;23(2):22634.

    42. Lincoln M, Johnston K, Muldoon M, et al. Com-

    bined arthroscopic and modified open approach

    for cam femoroacetabular impingement: a prelimi-

    nary experience. Arthroscopy 2009;25(4):3929.

    43. Malviya A, Stafford GH, Villar RN. Impact of

    arthroscopy of the hip for femoroacetabular

    impingement on quality of life at a mean follow-up

    of 3.2 years. J Bone Joint Surg Br 2012;94(4):46670.44. Matsuda DK, Carlisle JC, Arthurs SC, et al.

    Comparative systematic review of the open dislo-

    cation, mini-open, and arthroscopic surgeries for

    femoroacetabular impingement. Arthroscopy

    2011;27(2):25269.

    45. Meftah M, Rodriguez JA, Panagopoulos G, et al.

    Long-term results of arthroscopic labral debride-

    ment: predictors of outcomes. Orthopedics 2011;

    34(10):e58892.

    46. Murphy S, Tannast M, Kim YJ, et al. Debridement of

    the adult hip for femoroacetabular impingement: in-

    dications and preliminary clinical results. Clin Or-

    thop Relat Res 2004;(429):17881.

    47. Nho SJ, Magennis EM, Singh CK, et al. Outcomes

    after the arthroscopic treatment of femoroacetabu-

    lar impingement in a mixed group of high-level ath-

    letes. Am J Sports Med 2011;39(Suppl):14S9S.

    48. Peters CL, Erickson JA. Treatment of femoro-

    acetabular impingement with surgical dislocation

    and debridement in young adults. J Bone Joint

    Surg Am 2006;88(8):173541.

    49. Peters CL, Schabel K, Anderson L, et al. Open

    treatment of femoroacetabular impingement is

    associated with clinical improvement and low

    complication rate at short-term followup. Clin Or-

    thop Relat Res 2010;468(2):50410.

    50. Philippon MJ, Briggs KK, Yen YM, et al. Outcomes

    following hip arthroscopy for femoroacetabular

    impingement with associated chondrolabral

    dysfunction: minimum two-year follow-up. J Bone

    Joint Surg Br 2009;91(1):1623.

    51. Philippon MJ, Yen YM, Briggs KK, et al. Early out-

    comes after hip arthroscopy for femoroacetabular

    impingement in the athletic adolescent patient: a

    preliminary report. J Pediatr Orthop 2008;28(7):

    70510.

    52. Rebello G, Spencer S, Millis MB, et al. Surgical

    dislocation in the management of pediatric and

    adolescent hip deformity. Clin Orthop Relat Res

    2009;467(3):72431.

    53. Ribas M, Marin-Pena OR, Regenbrecht B, et al. Hip

    osteoplasty by an anterior minimally invasive

    approach for active patients with femoroacetabular

    impingement. Hip Int 2007;17(2):918.

    54. Tran P, Pritchard M, ODonnell J. Outcome of

    arthroscopic treatment for cam type femoroacetab-

    ular impingement in adolescents. ANZ J Surg

    2013;83(5):3826.

    55. Yun HH, Shon WY, Yun JY. Treatment of femoroace-

    tabular impingement with surgical dislocation. Clin

    Orthop Surg 2009;1(3):14654.

    56. Beaule PE, Allen DJ, Clohisy JC, et al. The young

    adult with hip impingement: deciding on the

    optimal intervention. Instr Course Lect 2009;58:

    21322.

    57. Clohisy JC, McClure JT. Treatment of anterior fem-oroacetabular impingement with combined hip

  • arthroscopy and limited anterior decompression.

    Iowa Orthop J 2005;25:16471.

    58. Laude F, Sariali E, Nogier A. Femoroacetabular

    impingement treatment using arthroscopy and

    anterior approach. Clin Orthop Relat Res 2009;

    467(3):74752.

    59. Nepple JJ, Zebala LP, Clohisy JC. Labral disease

    associated with femoroacetabular impingement:

    do we need to correct the structural deformity?

    J Arthroplasty 2009;24(Suppl 6):1149.

    60. Byrd JW, Jones KS. Arthroscopic femoroplasty in

    the management of cam-type femoroacetabular

    impingement. Clin Orthop Relat Res 2009;467(3):

    73946.

    61. Clohisy JC, St John LC, Schutz AL. Surgical

    treatment of femoroacetabular impingement: a

    systematic review of the literature. Clin Orthop

    Relat Res 2010;468(2):55564.

    62. Horisberger M, Brunner A, Herzog RF. Arthro-

    scopic treatment of femoroacetabular impingement

    of the hip: a new technique to access the joint. Clin

    Orthop Relat Res 2010;468(1):18290.

    63. Larson CM, Giveans MR, Stone RM. Arthroscopic

    debridement versus refixation of the acetabular

    labrum associated with femoroacetabular impinge-

    ment: mean 3.5-year follow-up. Am J Sports Med

    2012;40(5):101521.

    64. Philippon MJ, Weiss DR, Kuppersmith DA, et al.

    Arthroscopic labral repair and treatment of fem-

    oroacetabular impingement in professional

    hockey players. Am J Sports Med 2010;38(1):

    99104.

    Femoroacetabular Impingement 589

    Femoroacetabular ImpingementKey pointsWhat is femoroacetabular impingement?ClassificationPathophysiologyClinical presentationPrevalence of diseaseCausative role in osteoarthritisTreatmentNonoperative managementSurgical managementSurgical DislocationAnterior Mini Arthrotomy, With or Without Arthroscopic AssistanceArthroscopy

    OutcomesNonoperative ManagementSurgical DislocationAnterior Mini Arthrotomy, With or Without Arthroscopic AssistanceArthroscopy

    Future directionsReferences