The Knee xxx (2014) xxx–xxx

THEKNE-01860; No of Pages 5

Contents lists available at ScienceDirect

The Knee

Case report

Trabecular Metal Patella — Is it really doomed to fail in the totallypatellar-deficient knee? A case report of patellar reconstruction with anovel technique

Shashi Kumar Nanjayan a,⁎, Shashi Kumar Nanjayan a, Timothy Wilton b

a Registrar in Trauma & Orthopaedics, Royal Derby Hospital, Derby, DE22 3NE, UKb Consultant Trauma & Orthopaedic Surgeon, Royal Derby Hospital, Derby, DE22 3NE, UK

⁎ Corresponding author at: 47, Manor Park Court, Utt3NG, UK. Tel.: +44 790 3383 779.

E-mail address: shashikumartn@gmail.com (S. Kumar

Please cite this article as: KumarNanjayan S, ereport of patellar reconstruction with a nove

http://dx.doi.org/10.1016/j.knee.2014.02.0060968-0160/© 2014 Elsevier B.V. All rights reserved.

a b s t r a c t

a r t i c l e i n f o

Article history:Received 25 July 2013Received in revised form 25 January 2014Accepted 3 February 2014Available online xxxx

Keywords:Trabecular Metal PatellaPatellar bone stock deficiencyPatellar reconstruction

Reconstruction of the patella poses real problems for the revision TKR surgeon, particularly when the patella isabsent, fractured or profoundly deficient. The Trabecular Metal Patella was introduced in an attempt to addressthese issues. However the largest series of such cases published to date cast serious doubts on the validity of usingTrabecular Metal (TM) in cases where there is no residual patellar bone stock at all. We present a case where theTM Patellar implant has survived satisfactorily for 8 years post reconstruction in a knee with no residual patellabone, resulting in greatly improved symptoms and function. We believe that this success might be related tospecific technical details in the reconstruction and we present the technique.

© 2014 Elsevier B.V. All rights reserved.

1. Introduction

Reconstruction of the patella and ensuring reasonable quadricepsfunction are real problems for the revision TKR surgeon, and this appliesparticularly when the patella is absent, fractured or profoundlydeficient. Although there have been some reports of reasonable clinicaloutcome after primary TKR in patients with no patella [1–3] the resultsare generally inferior to those patients with an intact patella whethernormal or worn. There is no doubt that absence or severe deficiency ofthe patella presents much greater difficulty to the surgeon at revisionTKR.

Maintaining roughly the normal thickness of the patella is importantfor the maintenance of the effective strength of the quadricepsmechanism [4]. Although whole patellar allografts and quadricepsallografts have been described as a means of restoring the patellar/quadriceps lever-arm and treating extensor mechanism discontinuity[5–7], serious allograft complications such as infection, stretching,rejection and resorption can occur [8,9].

The Trabecular Metal Patella was introduced in an attempt toaddress these issues and restore patellar bone stock. However thelargest series of such cases published to date cast serious doubts on

oxeter New Road, Derby DE22

Nanjayan).

t al, TrabecularMetal Patella—l technique, Knee (2014), htt

the validity of using Trabecular Metal (TM) in cases where there is noresidual patellar bone stock at all [8], and similar poor results werereported by Kwong et al. both in patello-femoral replacement and TKR[9].

We present a case where the TM implant has survived satisfactorilyfor eight years post reconstruction in a knee with no residual patellarbone, resulting in greatly improved symptoms and function.We believethat this success might be related to specific technical details in thereconstruction and we present the technique.

2. Case presentation

Our patient is a 68-year-old lady who was diagnosed with rheu-matoid arthritis in the 1960s. At that time she was treated in plasterfor 1 month for left knee symptoms. Post plaster, she developed se-vere stiffness of the knee. She subsequently suffered a septic arthritisand worsening of rheumatoid arthritis following an injection of thesame knee. A total patellectomywas performed also in the 1960s, ap-parently due to symptoms subsequently attributed to septic arthritisand rheumatoid arthritis. She underwent debridement followed bytotal knee replacement later during the 1960s. Subsequent failureoccurred several times. She underwent the first revision in 1975 forimplant failure, which lasted for 15 years. The second revision wasperformed in the 1990s which lasted only a few years finally comingto the 3rd revision in 2004. When seen in 2004, prior to the 3rd revi-sion TKR, she had symptoms of night pain as well as instability,

Is it really doomed to fail in the totally patellar-deficient knee? A casep://dx.doi.org/10.1016/j.knee.2014.02.006

Fig. 2. Securing Trabecular Metal shell inside the quadriceps pocket with provisionalsutures.

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weakness and inability to walk more than 100 yards. She was using amotorised scooter despite being only 59 years old. The quadricepsweakness was profound and was felt to be contributing significantlyto her disability.

Revision was carried out because of these symptoms. Flexion of theknee prior to revision was 5–110°. There was significant varus/valguslaxity and revision to a rotating hinge implant was undertaken.

The patient had no residual patellar bone stock for the placementand attachment of a TM shell. The implant was therefore attached di-rectly to the quadriceps tendon. Details of the operative technique aredescribed below in an attempt to reconcile this good result with thosevery poor results subsequently reported in the paper by both Rieset al. [8] and Kwong et al. [9].

Immediate post-operative recovery was uneventful. During rehabil-itation after the TKR, she was relatively pain free, had good ROM and astable knee. Patellar tracking was normal.

For two years the patient had some discomfort and problemswhen seen in clinic, raising concerns about the survival of the recon-struction following the review by Ries et al. [8], which was publishedduring those two years. Symptoms were not bad enough to justifyfurther surgery and the radiographs repeatedly showed the implantto be properly located.

The symptoms then improved significantly and at eight years followup thepatient now remains pain freewithout anydiscomfort in her activ-ities of daily living. She feels that she is much better than after her prima-ry TKR. Pain is substantially relieved with no pain walking on a flatsurface, going up stairs andmoderate pain going down stairs or on twist-ing while bearing weight. She can lead on stairs going up using the oper-ated leg. There is mild pain on full flexion or on standing for long periods.There is noflexion contracture and the kneeflexes to 110°. Instabilitywaseliminated by the hinged implant and she has no extensor lag.

3. Surgical technique

• A pocket was created in the quadriceps tendon via the cut edge of thearthrotomy at the level determined by the provisional placement of abutton on the surface once the femoral and tibial components wereimplanted. Neither the anterior nor posterior surface of the quadri-ceps tendon was breached at this stage (Fig. 1)

• A Trabecular Metal shell was placed in the pocket. The TrabecularMetalwas securedwithin the quadriceps tendonwith two provisionalinterrupted mattress sutures (sutures were passed through the TMshell and through the quadriceps tendon both anterior surface andposterior surface) as shown in Fig. 2.

Fig. 1. A pocket was created in the quadriceps t

Please cite this article as: KumarNanjayan S, et al, TrabecularMetal Patellareport of patellar reconstruction with a novel technique, Knee (2014), htt

• The positionwas then checked by putting the knee through a range offlexion and adjusted vertically and horizontally as necessary. All re-maining sutures had to be passed prior to any being tied and priorto cementing the polyethylene button onto the TM implant in orderto allow proper suture placement. The position of the implant waschecked after each suture was placed (Fig. 3).

• The patellar button was then cemented in place onto the TM compo-nent through this soft-tissue window, followed by the tying of all sixhorizontal mattress sutures (Fig. 4).

• The undersurface of the quadriceps tendon overlying the button wasthen windowed in a circular configuration to expose only the centreof the patellar button and allow this to come in direct contact with

endon via the cut edge of the arthrotomy.

— Is it really doomed to fail in the totally patellar-deficient knee? A casep://dx.doi.org/10.1016/j.knee.2014.02.006

Fig. 3. Remaining sutures passed through the TM shell before cementing the patellar button.

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the trochlear groove of the femoral component (Fig. 5)• A further circumferential “purse string” suture was inserted, in ananteroposterior fashion, as with a sewing machine, to discourage theedges of the window from lifting off the underlying tendon (Fig. 6)

• All of the sutures were tied on the anterior surface of the tendon(Fig. 7).

A lateral release was unnecessary as the implant was positioned toavoid the need for such intervention. After the surgery the patient wastreated as per routine hospital protocol for revision TKR that includedmobilising full weight bearing using crutches andwalking frame as tolerat-ed, unrestricted passive and active range of movements of the knee. Iso-metric quadriceps exercises were started the day after surgery. Check X-rays remain satisfactory, with no loosening, wear or evidence of patellardisplacement (Fig. 8a, b, c).

4. Discussion

Reconstruction of the deficient patella using various types of bonegrafts has been recommended over the years. Cancellous bone allograftplaced into a synovial pouch has been described as effective in

Fig. 4. Cementing the patella

Please cite this article as: KumarNanjayan S, et al, TrabecularMetal Patella—report of patellar reconstruction with a novel technique, Knee (2014), htt

improving bone stock [10]. In many cases however, such bone graftswhether autograft or allograft do tend to disappear partially orcompletely post operatively due to resorption. TrabecularMetal was in-troduced as a potential method of reconstructing the patella in order toavoid these difficulties.

The importance of residual patellar bone stock has been stronglyemphasised by Ries et al. [8]. They reported failure of all seven knees(six patients) where there was no residual bone in contact with theTM patellar component, and these failures (loosening) occurredwithin 1 year. Observed complications were loosening of the com-ponent, migration and soft tissue necrosis leading to disruption ofextensor mechanism.

Restoration of the extensormechanism, proper patellar tracking andgood anatomical relationships with femoral and tibial components arecritical for optimal clinical outcome and this poses a real surgical chal-lenge. Although many options have been described in the literaturefor revision of patellar component in patients with severe patellar defi-ciency, results have been less encouraging [11].

Trabecular Metal is made of porous tantalum, provides a rough,highly porous surface, similar to trabecular bone, and has beenshown to have favourable ingrowth properties [12]. The question is

r button to the TM shell.

Is it really doomed to fail in the totally patellar-deficient knee? A casep://dx.doi.org/10.1016/j.knee.2014.02.006

Fig. 5. Undersurface of the quadriceps tendon overlying the button being windowed in acircular configuration to expose the centre of the patellar button.

Fig. 6. Circumferential sutures to the quadriceps tendon around the Trabecular MetalPatella.

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whether this favourable ingrowth can apply to soft-tissue as well asbone.

We believe that Trabecular Metal Patella could still have animportant role to play in primary and revision TKR and there isscope for using and improving this technique in carefully selectedcases of primary or revision TKR where the patella is particularlydeficient.

Considering the reported outcomes [8], the excellent outcome in ourpatient is probably related to the quality and stability of the soft tissueattachment to tantalum [13,14] and the technique adopted. We arenot aware of any such technique appearing hitherto in the literature.

There is little doubt that further work is needed to validate thistechnique. In the senior author's practice the method was not usedagain for some years due to the previously reported very poor results[8,9]. However the good long-term outcome of our patient shouldperhaps lead to the technique being considered once again albeitwith great care.

5. Conflict of interest

The authors have no conflict of interest to declare.

References

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[2] Kang JD, Papas SN, Rubash HE, McClain Jr EJ. Total knee arthroplasty inpatellectomized patients. J Arthroplasty 1993;8:489–501.

[3] Paletta Jr GA, Laskin RS. Total knee arthroplasty after a previous patellectomy. J BoneJoint Surg Am 1995;77:1708–12.

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[5] Emerson Jr RH, Head WC, Malinin TI. Extensor mechanism reconstruction with anallograft after total knee arthroplasty. Clin Orthop Relat Res 1994:79–85.

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[7] Engh CA, O'Connor D, Jasty M, McGovern TF, Bobyn JD, Harris WH.Quantification of implant micromotion, strain shielding, and bone resorptionwith porous-coated anatomic medullary locking femoral prostheses. ClinOrthop Relat Res 1992:13–29.

[8] Ries MD, Cabalo A, Bozic KJ, Anderson M. Porous tantalum patellar augmentation:the importance of residual bone stock. Clin Orthop Relat Res 2006;452:166–70.

[9] Kwong Y, Desai VV. The use of a tantalum-based augmentation patella in patientswith a previous patellectomy. Knee 2008;15:91–4.

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[11] Garcia RM, Kraay MJ, Conroy-Smith PA, Goldberg VM. Management of thedeficient patella in revision total knee arthroplasty. Clin Orthop Relat Res2008;466:2790–7.

[12] Bobyn JD, Stackpool GJ, Hacking SA, Tanzer M, Krygier JJ. Characteristics of boneingrowth and interface mechanics of a new porous tantalum biomaterial. J BoneJoint Surg Br 1999;81:907–14.

[13] Hacking SA, Bobyn JD, Toh K, Tanzer M, Krygier JJ. Fibrous tissue ingrowth andattachment to porous tantalum. J Biomed Mater Res 2000;52:631–8.

[14] Reach Jr JS, Dickey ID, Zobitz ME, Adams JE, Scully SP, Lewallen DG. Direct tendonattachment and healing to porous tantalum: an experimental animal study. J BoneJoint Surg Am 2007;89:1000–9.

— Is it really doomed to fail in the totally patellar-deficient knee? A casep://dx.doi.org/10.1016/j.knee.2014.02.006

Fig. 8. a. Radiograph at 8 year follow-up, anteroposterior view. b. Radiograph at 8 yearfollow-up, lateral view. c. Radiograph at 8 year follow-up, skyline view.

Fig. 7. Circumferential sutures on the anterior surface of the tendon.

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Please cite this article as: KumarNanjayan S, et al, TrabecularMetal Patella— Is it really doomed to fail in the totally patellar-deficient knee? A casereport of patellar reconstruction with a novel technique, Knee (2014), http://dx.doi.org/10.1016/j.knee.2014.02.006