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Mid-term results of the FPV patellofemoral joint replacement
The Knee 21 (2014) 138–141
Contents lists available at ScienceDirect
The Knee
Mid-term results of the FPV patellofemoral joint replacement N. Al-Hadithy, R. Patel 1, B. Navadgi, S. Deo, D. Hollinghurst, V. Satish ⁎ Great Western Hospital, Marlborough Road, Swindon, United Kingdom
a r t i c l e
i n f o
Article history: Received 15 April 2013 Received in revised form 14 August 2013 Accepted 16 August 2013 Keywords: Knee arthroplasty Osteoarthritis FPV Patellofemoral
a b s t r a c t Background: Isolated patellofemoral joint osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial. The Femoro Patella Vialli (FPV) patellofemoral joint replacement (Wright Medical Technology, UK) has been shown to restore functional kinematics of the knee close to normal. Despite its increasing popularity in recent years, there are no studies evaluating the mid-term results with an objective scoring assessment. Aims: Therefore, the aim of this study was to report the clinical and radiological outcomes of FPV patellofemoral joint replacement in patients with isolated patellofemoral arthritis. Methods: Between 2006 and 2012, we performed 53 consecutive FPV patellofemoral arthroplasties in 41 patients with isolated patellofemoral joint osteoarthritis. The mean follow-up was 3 years. Results: Mean Oxford Knee Scores improved from 19.7 to 37.7 at latest follow-up. The progression of tibiofemoral osteoarthritis was seen 12% of knees. Two knees required revision to TKR at 7 months post-operatively, which we attribute to poor patient selection. We had no cases of maltracking patellae, and no lateral releases were performed. Conclusion: Our findings suggest the FPV patellofemoral prosthesis provides good pain relief and survivorship with no significant maltracking patellae. © 2013 Elsevier B.V. All rights reserved.
1. Background Isolated patellofemoral joint (PFJ) osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial [1]. Joint sparing procedures including arthroscopic debridement, patellar facetectomy [2], lateral release [3] and chondrocyte implantation [4] have produced unsatisfactory results [5]. Although total knee replacement (TKR) provides reliable pain relief in 90% of patients with isolated PFJ arthritis, many surgeons prefer a joint preserving procedure particularly when patients are younger and more active [6]. Although patellofemoral arthroplasty was first introduced in 1955 by McKeever [7], high early failure rates prompted many surgeons to resort to TKR. However, more recently, there has been renewed interest with promising results. This is due to improved design, instrumentation, less invasive surgical techniques and better patient selection [8,9]. However, concerns remain regarding progression of tibiofemoral osteoarthritis and maltracking patella. The femoro patella vialli (FPV) patellofemoral joint replacement (Wright Medical Technology, UK) has been shown to restore functional kinematics of the knee close to normal [10] and has several key design
⁎ Corresponding author at: Great Western Hospital, Swindon, United Kingdom. Tel.: +44 7795463677. E-mail addresses: [email protected] (R. Patel), [email protected] (V. Satish). 1 Downderry, Old Vicarage Lane, Swindon, SN3 4SR, UK. 0968-0160/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.knee.2013.08.010
improvements to prevent patellar maltracking. Despite its increasing popularity in recent years, there are no studies evaluating the midterm results with an objective scoring assessment [6]. Therefore, the aim of this study was to determine whether this design produced satisfactory patellar tracking and to report the clinical and radiological outcomes of the FPV patellofemoral joint arthroplasty in patients with isolated patellofemoral arthritis.
2. Patients and methods Between 2006 and 2012 years, 53 consecutive FPV patellofemoral arthroplasties were performed in 41 patients. Twelve patients had bilateral simultaneous procedures. There were 31 females and 10 males with a mean age of 62.2 years (39–86) and a mean follow-up of 37 months (range: 12–70 months). All patients were seen postoperatively at 6 weeks, 6 months and yearly thereafter. PFJ replacements were performed on the right knee in 33 patients and left in 20 patients. The indications for PFJ replacement was isolated PFJ bone on bone arthritis resistant to physiotherapy, analgesia and joint injections. Diagnosis was based on clinical, radiological and where available arthroscopic findings. Clinical findings included retropatellar pain worse on kneeling or ascending/descending stairs and absence of significant medial/lateral joint line tenderness. Radiographs included weight-bearing anteroposterior, lateral and skyline views; any patients with moderate tibiofemoral degenerative changes were excluded. In cases where the diagnosis was in doubt, a pre-operative arthroscopy was performed (21 knees; 40%). In
N. Al-Hadithy et al. / The Knee 21 (2014) 138–141
those cases, patellofemoral joint replacement surgery was only performed in patients with severe patellofemoral osteoarthritis and minimal tibiofemoral chondral defects (grade 2 or less and b10 mm2). No other preceding surgery was performed on any of the remaining patients. All procedures were performed by one of the 4 senior surgeons. Exclusion criteria included generalised osteoarthritis, chondral defects (N10 mm) in other compartments and patients with fixed flexion deformities greater than 10° or flexion less than 90°. Functional and pain assessment was performed using the Oxford Knee Score (OKS) [11] and clinical examination. Radiological assessment included anteroposterior, lateral and skyline [12] views of the knee and were reviewed by two independent assessors. Patellar tilt was assessed using the method described by Grelsamer et al. [12]. Surgery was performed as described by Shakespeare [13], via a medial-parapatellar approach with a peri-patellar release to evert the patella and allow patellar resection. In all cases, the patella was resurfaced. The patellar osteotomy was performed using the principles described by Lee and Kim [14]. The anterior resection guide is placed on top of the anterior femoral cortex and rested on the distal femur in a stable position. Rotation is checked by using a detachable extramedullary tibial guide. No intramedullary reference was used. The trochlear cut was made which spanned the distal femur but did not encroach on the intercondylar notch. Once the femoral cuts are made, curettage or burring may be required for any residual trochlear cartilage to ensure adequate cement fixation and proper seating of the femoral component. The implants are then trialled. A key advantage of the FPV implant is that the patellar trial can be clamped loosely enough to allow selflocation of the patellar ridge with the trochlear groove during repeated flexion and extension. Once correct rotation has been achieved the clamp can be tightened and subsequently drilled for definitive cemented fixation. No lateral releases were required and no patients required other procedures for patellar maltracking. Drains were not used. Physiotherapy started on day 1. Patients were reviewed at 6 weeks, 6 months and yearly thereafter. Statistical analysis on function was performed using the paired t-test. A value of p b 0.05 was considered significant.
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changes on the immediate postoperative radiographs. In three months, this had progressed to bone-on-bone arthritis of the right knee. He was subsequently revised to bilateral TKRs at 7 months after his initial surgery, which were uncomplicated (Fig. 1). He has resumed high impact gym activities and is satisfied with his outcome. The second patient had persistent pain over the lateral border of her patella and had pain on extension. She subsequently had an arthroscopy 9 months later where scar tissue was resected over her lateral parapatellar region. She subsequently resumed all activities and was very satisfied with her outcome when reviewed at three months post arthroscopy. There were no wound infections or deep infections.
3. Results One patient (2 knees) died from unrelated causes, and 1 patient was not contactable, leaving 39 patients (49 knees) available for follow-up. Mean hospital stay was 2 days.
4. Functional outcome Oxford Knee Scores improved from a mean of 19.7 (4–37) preoperatively, to 32.1 at one year follow-up and 37.7 at last follow-up (p b 0.05). The mean flexion pre-operatively was 120° (60°–140°) and postoperatively was unchanged at 120° (70°–135°) at final follow-up. No patients were found to have a maltracking patella at follow-up either subjectively, on clinical assessment or on radiological view (skyline). 5. Radiological outcome There were no cases of loosening. Six knees (four patients) had progression of osteoarthritis in the tibiofemoral compartment. All 6 were graded as mild and patients did not have progression of symptoms. We had three cases of patellar tilt greater than 5° (mean 7.7°). 6. Re-operations/revisions Three knees (two patients) had further operations, with one bilateral revision and one re-operation. The patient who underwent revision was found to have lateral compartment degenerative
Fig. 1. (a) Immediate post-operative radiograph, revealing lateral compartment degenerative changes. (b) Progression of lateral compartment osteoarthritis. (c) Revised to bilateral TKR with a satisfactory outcome.
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7. Discussion Our results show that the FPV patellofemoral joint replacement provides good mid-term results, with a 97% survival rate at three years, comparable to other patellofemoral joint replacements [9,15], improvement in pain and with no cases of patellar maltracking despite not performing any lateral releases. Various other studies have evaluated the Avon patellofemoral joint replacement (Stryker Howmedica, Osteonics, Allendale, New Jersey). Ackroyd et al. [15] published their results from the designer institution and found mean improvements in OKS from 18 to 39, and a 96% survivorship in their series of 83 knees with a five-year follow-up. One patient had a maltracking patella which required soft-tissue realignment. Odumenya et al. [9] and Starks [16] found similar results in their series from independent centres with significant gains in OKS with only one requiring subsequent lateral release for persistent patellar instability. Our results were similar, with improvements in Oxford Knee Scores from 19.7 pre-operatively to 32.1 at one year and 37.7 at latest follow-up. The mean range of motion was unchanged before and after surgery, which is in keeping with other studies. Outcomes of clinical studies are summarised in Table 1. Despite the FPV replacement increasing in popularity and now being the second most used PFJ replacement in the UK [6], only one other study has evaluated its outcome. Mohammed et al. [17] reviewed 91 patients who underwent 101 PFJ replacements using three different implants (FPV, Avon, Lubinus), with only 30 having the FPV implant at a mean of 48 months follow-up. It is important to note that despite a mean follow-up of 48 months; they implanted Lubinus implants initially before abandoning it due to high failure rates, to only later implant FPV or Avon PFJ replacements, indicating that the follow-up for FPV may have been significantly shorter. Furthermore, their results were not stratified according to implant design, and there was no objective pre- or post-operative scoring criterion (e.g., OKS) making assessment of the FPV implant difficult. Up to 32% of patients required procedures for maltracking patellae (lateral release 23% & tibial tuberosity transfer 9%). Only two (6%) FPVs required further procedures (arthroscopic debridement), compared with 24% and 43% for the Avon and Lubinus respectively. Importantly no FPVs required lateral releases. A key difference of the FPV over other patellofemoral implants is a larger component sulcus angle of 140° (Fig. 2) compared with 125° and 110° for the Avon and Lubinus implants respectively and more closely mimics the normal knee which is approximately 138°–140°
Fig. 2. Large trochlea sulcus angle of 140° closer mimics normal anatomy.
[18,19] (Fig. 2). Monk et al. [10] compared the kinematics of the FPV prosthesis with the normal knee by assessing the relationship between patella tendon angle (PTA) and knee flexion angle (KFA). They found no differences between the two groups, except at 50° of knee flexion. This contrasts with the Avon prosthesis where there were significant differences from 0° to 90° of knee flexion [20]. Furthermore, the patella and trochlea are both facetted allowing a greater contact area. In contrast, the Avon prosthesis has a dome-shaped patella, which allows point contact with a flatter broad based trochlea. Congruity between the patella and trochlea is ensured by using a patellar clamp which allows selfalignment prior to definitive fixation. We believe these are the reasons that no patients had maltracking patellae at follow-up and none required intra-operative lateral releases in our series. The main benefits of patellofemoral joint replacement over TKR include preservation of bone stock and maintenance of the normal tibiofemoral joint and surrounding ligaments and soft tissues. This allows for a less invasive surgical procedure, faster recovery and a more simple revision to TKR if needed. A recent study by Lonner et al. [21] found that the results of TKR after failed patellofemoral replacement were not compromised. Our results reflect this with our 1 patient who underwent revision having a satisfactory outcome. The main concern of patellofemoral joint replacement is progression of tibiofemoral osteoarthritis, therefore making correct patient selection extremely
Table 1 Summary of outcomes of Avon and FPV PFJR. Author
PFJ Implant
No. of cases
Age (years)
Follow-up (months)
Outcomes
Flexion before and after
Complications/further procedures
Al-Hadithy
FPV
49
62
37
120°–120°
Mohammed et al. [17]
Lubinus FPV Avon
46 30 25
57
48
Pre-op OKS 19.7 Post OP OKS 37.7 73% did very well —authors subjective assessment
Starks [16]
Avon
37
66
24
Post op OKS 39
Not stated
Leadbetter [24]
Avon
79
58
36
13 clinical failures
Not stated
Ackroyd et al. [15]
Avon
90
68
62
Pre-op OKS – 18 Post op OKS 39
113°–115°
Odumenya et al. [9]
Avon
50
66
64
Post op OKS 30.5
120°–120°
2 Revision to TKR 1 Arthroscopic debridement 18 Arthroscopic debridement 8 Lateral release 3 Tibial tuberosity transfer 4 Revision to TKR 1 Staged patella resurfacing 1 Patella fracture 1 Patella tendon rupture 1 Tibial tuberosity fracture 1 Arthrofibrosis 2 Arthroscopic evacuation of haematoma 1 Manipulation for stiffness 1 Patella instability required distal soft tissue realignment 4 revision for progression of OA 7 Lateral subluxation 1 Lateral release Not stated number of intra-operative lateral releases
OKS = Oxford Knee Score, KSS = Knee Society Score, OA = osteoarthritis
25% lost last 10° of flexion, and 5% lost 5° of extension
N. Al-Hadithy et al. / The Knee 21 (2014) 138–141
important. The progression of tibiofemoral osteoarthritis ranges from 12% to 24% depending on follow-up duration [22,23]. We had 6 cases (12%) of radiological progression of tibiofemoral osteoarthritis. One patient was revised to bilateral TKRs; however, in retrospect, we attribute this to poor patient selection as lateral compartment degenerative changes were seen on the immediate postoperative radiographs. We are now considering the routine use of Schuss views in addition to standing anteroposterior, lateral and skyline views in all patients being considered for PFJ replacements. We acknowledge the limitations of this study being retrospective and without randomisation. Measurement bias was minimised by having two independent assessors who were not involved with the original operations and by blinding the operating surgeons to the assessment. We conclude that the FPV patellofemoral joint replacement appears to be a reliable prosthesis in patients with isolated patellofemoral osteoarthritis, which at a mean follow-up of three years, has a high survival rate, provides gives good pain relief, with high functional scores and reliably allows normal patellar tracking without the need for an extensive lateral release. 8. Conflict of interest The authors certify that we have no commercial associations (e.g., employment, consultations, stock ownership, honoria, paid expert testimony, patent applications/registrations, and grants or other funding, etc) that might pose a conflict of interest in connection with the submitted article. References [1] Davies AP, Vince AS, Shepstone L, Donell ST, Glasgow MM. The radiologic prevalence of patellofemoral osteoarthritis. Clin Orthop Relat Res 2002;402:206–12. [2] Yercan HS, Ait Si Selmi T, Neyret P. The treatment of patellofemoral osteoarthritis with partial lateral facetectomy. Clin Orthop Relat Res Jul 2005;436:14–9. [3] Aderinto J, Cobb AG. Lateral release for patellofemoral arthritis. Arthroscopy Apr 2002;18(4):399–403. [4] Minas T, Bryant TRN. The role of autologous chondrocyte implantation in the patellofemoral joint. Clin Orthop Relat Res Jul 2005;436:30–9.
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[5] Lonner JH. Patellofemoral arthroplasty. Pros, cons and design considerations. Clin Orthop Relat Res 2004;428:158–65. [6] National Joint Registry for England and Wales. 9th Annual Report; 2012. [7] McKeever DC. Patellar prosthesis. J Bone Joint Surg Am 1955;37-A:1074–84. [8] Leadbetter WB, Ragland PS, Mont MA. The appropriate use of the patellofemoral arthroplasty: an analysis of reported indications, contraindications and failures. Clin Orthop Relat Res 2005;436:47–54. [9] Odumenya M, Costa ML, Parsons N, Achten J, Dhillon M, Krikler SJ. The Avon patellofemoral joint replacement. Five-year results from an independent centre. J Bone Joint Br 2010;92-B:56–60. [10] Monk AP, van Duren BH, Pandit H, Shakespeare D, Murray DW, Gill HS. In vivo sagittal plane kinematics of the FPV patellofemoral replacement. Knee Surg Sports Traumatol Arthrosc 2012;20:1104–9. [11] Dawson J, Fitzpatrick R, Murray D, Carr A. Questionnaire on the perceptions of patients about total knee replacement. J Bone Joint Surg Br 1998;80-B:63–9. [12] Grelsamer RP, Bazos AN, Proctor CS. Radiographic analysis of patellar tilt. J Bone Joint Surg Br 1993;75-B:822–4. [13] Shakespeare D. FPV Patello-femoral replacement surgical technique. EVOS instrumentation. Wright Medical 2007. [14] Lee TQ, Kim WC. Anatomically based patellar resection criteria for total knee arthroplasty. Am J Knee Surg 1998;3(1):161–5. [15] Ackroyd CE, Newman JH, Evans R, Eldridge JDJ, Joslin CC. The Avon patellofemoral arthroplasty. Five-year survivorship and functional results. J Bone Joint Surg Br 2007;89-B:310–5. [16] Starks I, Roberts S, White SH. The Avon patellofemoral joint replacement. Independent assessment of early functional outcomes. J Bont Joint Surg Br 2009;91-B:1579–82. [17] Mohammed R, Jimulia T, Durve K, Bansal M, Green M, Learmonth D. Medium-term results of patellofemoral jointarthroplasty. Acta Orthop Belg 2008;74:472–7. [18] Davies AP, Costa ML, Donnell ST, Glasgow MM, Shepstone L. The sulcus angle and malalignment of the extensor mechanism of the knee. J Bone Joint Surg Br 2000;82-B:1162–6. [19] Merchant AC. Patellofemoral disorders: biocmechanics, diagnosis and nonoperative treatment. In: McGinty JB, editor. Operative Arthroscopy. New York: Raven Press; 1991. p. 261–75. [20] Hollinghurst D, Stoney J, Ward T, Pandit H, Beard D, Murray DW. In vivo sagittal plane kinematics of the avon patellofemoral arthroplasty. J Arthroplasty 2007;22(1):117–23. [21] Lonner JH, Jasko JG, Booth Jr RE. Revision of a failed patellofemoral arthroplasty to a total knee arthroplasty. J Bone Joint Surg Am Nov 2006;88(11):2337–42. [22] Kooijman HJ, APPm Driessen, van Horn JR. Long-term results of patellofemoral arthroplasty: a report of 56 arthroplasties with 17 year follow-up. J Bone Joint Surg Br 2003;85-B:836–40. [23] Nicol SG, Loveridge JM, Weale AE, Ackroyd CE, Newman JH. Arthritis progression after patellofemoral joint replacement. Knee Aug 2006;13(4):290–5. [24] Leadbetter WB, Kolisek FT, Levitt RL, Brooker AF, Zietz P, Marker DR, et al. Patellofemoral arthroplasty: a multi-centre study with minimum 2-year follow-up. Int Orthop Dec 2009;33(6):1597–601.
Contents lists available at ScienceDirect
The Knee
Mid-term results of the FPV patellofemoral joint replacement N. Al-Hadithy, R. Patel 1, B. Navadgi, S. Deo, D. Hollinghurst, V. Satish ⁎ Great Western Hospital, Marlborough Road, Swindon, United Kingdom
a r t i c l e
i n f o
Article history: Received 15 April 2013 Received in revised form 14 August 2013 Accepted 16 August 2013 Keywords: Knee arthroplasty Osteoarthritis FPV Patellofemoral
a b s t r a c t Background: Isolated patellofemoral joint osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial. The Femoro Patella Vialli (FPV) patellofemoral joint replacement (Wright Medical Technology, UK) has been shown to restore functional kinematics of the knee close to normal. Despite its increasing popularity in recent years, there are no studies evaluating the mid-term results with an objective scoring assessment. Aims: Therefore, the aim of this study was to report the clinical and radiological outcomes of FPV patellofemoral joint replacement in patients with isolated patellofemoral arthritis. Methods: Between 2006 and 2012, we performed 53 consecutive FPV patellofemoral arthroplasties in 41 patients with isolated patellofemoral joint osteoarthritis. The mean follow-up was 3 years. Results: Mean Oxford Knee Scores improved from 19.7 to 37.7 at latest follow-up. The progression of tibiofemoral osteoarthritis was seen 12% of knees. Two knees required revision to TKR at 7 months post-operatively, which we attribute to poor patient selection. We had no cases of maltracking patellae, and no lateral releases were performed. Conclusion: Our findings suggest the FPV patellofemoral prosthesis provides good pain relief and survivorship with no significant maltracking patellae. © 2013 Elsevier B.V. All rights reserved.
1. Background Isolated patellofemoral joint (PFJ) osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial [1]. Joint sparing procedures including arthroscopic debridement, patellar facetectomy [2], lateral release [3] and chondrocyte implantation [4] have produced unsatisfactory results [5]. Although total knee replacement (TKR) provides reliable pain relief in 90% of patients with isolated PFJ arthritis, many surgeons prefer a joint preserving procedure particularly when patients are younger and more active [6]. Although patellofemoral arthroplasty was first introduced in 1955 by McKeever [7], high early failure rates prompted many surgeons to resort to TKR. However, more recently, there has been renewed interest with promising results. This is due to improved design, instrumentation, less invasive surgical techniques and better patient selection [8,9]. However, concerns remain regarding progression of tibiofemoral osteoarthritis and maltracking patella. The femoro patella vialli (FPV) patellofemoral joint replacement (Wright Medical Technology, UK) has been shown to restore functional kinematics of the knee close to normal [10] and has several key design
⁎ Corresponding author at: Great Western Hospital, Swindon, United Kingdom. Tel.: +44 7795463677. E-mail addresses: [email protected] (R. Patel), [email protected] (V. Satish). 1 Downderry, Old Vicarage Lane, Swindon, SN3 4SR, UK. 0968-0160/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.knee.2013.08.010
improvements to prevent patellar maltracking. Despite its increasing popularity in recent years, there are no studies evaluating the midterm results with an objective scoring assessment [6]. Therefore, the aim of this study was to determine whether this design produced satisfactory patellar tracking and to report the clinical and radiological outcomes of the FPV patellofemoral joint arthroplasty in patients with isolated patellofemoral arthritis.
2. Patients and methods Between 2006 and 2012 years, 53 consecutive FPV patellofemoral arthroplasties were performed in 41 patients. Twelve patients had bilateral simultaneous procedures. There were 31 females and 10 males with a mean age of 62.2 years (39–86) and a mean follow-up of 37 months (range: 12–70 months). All patients were seen postoperatively at 6 weeks, 6 months and yearly thereafter. PFJ replacements were performed on the right knee in 33 patients and left in 20 patients. The indications for PFJ replacement was isolated PFJ bone on bone arthritis resistant to physiotherapy, analgesia and joint injections. Diagnosis was based on clinical, radiological and where available arthroscopic findings. Clinical findings included retropatellar pain worse on kneeling or ascending/descending stairs and absence of significant medial/lateral joint line tenderness. Radiographs included weight-bearing anteroposterior, lateral and skyline views; any patients with moderate tibiofemoral degenerative changes were excluded. In cases where the diagnosis was in doubt, a pre-operative arthroscopy was performed (21 knees; 40%). In
N. Al-Hadithy et al. / The Knee 21 (2014) 138–141
those cases, patellofemoral joint replacement surgery was only performed in patients with severe patellofemoral osteoarthritis and minimal tibiofemoral chondral defects (grade 2 or less and b10 mm2). No other preceding surgery was performed on any of the remaining patients. All procedures were performed by one of the 4 senior surgeons. Exclusion criteria included generalised osteoarthritis, chondral defects (N10 mm) in other compartments and patients with fixed flexion deformities greater than 10° or flexion less than 90°. Functional and pain assessment was performed using the Oxford Knee Score (OKS) [11] and clinical examination. Radiological assessment included anteroposterior, lateral and skyline [12] views of the knee and were reviewed by two independent assessors. Patellar tilt was assessed using the method described by Grelsamer et al. [12]. Surgery was performed as described by Shakespeare [13], via a medial-parapatellar approach with a peri-patellar release to evert the patella and allow patellar resection. In all cases, the patella was resurfaced. The patellar osteotomy was performed using the principles described by Lee and Kim [14]. The anterior resection guide is placed on top of the anterior femoral cortex and rested on the distal femur in a stable position. Rotation is checked by using a detachable extramedullary tibial guide. No intramedullary reference was used. The trochlear cut was made which spanned the distal femur but did not encroach on the intercondylar notch. Once the femoral cuts are made, curettage or burring may be required for any residual trochlear cartilage to ensure adequate cement fixation and proper seating of the femoral component. The implants are then trialled. A key advantage of the FPV implant is that the patellar trial can be clamped loosely enough to allow selflocation of the patellar ridge with the trochlear groove during repeated flexion and extension. Once correct rotation has been achieved the clamp can be tightened and subsequently drilled for definitive cemented fixation. No lateral releases were required and no patients required other procedures for patellar maltracking. Drains were not used. Physiotherapy started on day 1. Patients were reviewed at 6 weeks, 6 months and yearly thereafter. Statistical analysis on function was performed using the paired t-test. A value of p b 0.05 was considered significant.
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changes on the immediate postoperative radiographs. In three months, this had progressed to bone-on-bone arthritis of the right knee. He was subsequently revised to bilateral TKRs at 7 months after his initial surgery, which were uncomplicated (Fig. 1). He has resumed high impact gym activities and is satisfied with his outcome. The second patient had persistent pain over the lateral border of her patella and had pain on extension. She subsequently had an arthroscopy 9 months later where scar tissue was resected over her lateral parapatellar region. She subsequently resumed all activities and was very satisfied with her outcome when reviewed at three months post arthroscopy. There were no wound infections or deep infections.
3. Results One patient (2 knees) died from unrelated causes, and 1 patient was not contactable, leaving 39 patients (49 knees) available for follow-up. Mean hospital stay was 2 days.
4. Functional outcome Oxford Knee Scores improved from a mean of 19.7 (4–37) preoperatively, to 32.1 at one year follow-up and 37.7 at last follow-up (p b 0.05). The mean flexion pre-operatively was 120° (60°–140°) and postoperatively was unchanged at 120° (70°–135°) at final follow-up. No patients were found to have a maltracking patella at follow-up either subjectively, on clinical assessment or on radiological view (skyline). 5. Radiological outcome There were no cases of loosening. Six knees (four patients) had progression of osteoarthritis in the tibiofemoral compartment. All 6 were graded as mild and patients did not have progression of symptoms. We had three cases of patellar tilt greater than 5° (mean 7.7°). 6. Re-operations/revisions Three knees (two patients) had further operations, with one bilateral revision and one re-operation. The patient who underwent revision was found to have lateral compartment degenerative
Fig. 1. (a) Immediate post-operative radiograph, revealing lateral compartment degenerative changes. (b) Progression of lateral compartment osteoarthritis. (c) Revised to bilateral TKR with a satisfactory outcome.
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7. Discussion Our results show that the FPV patellofemoral joint replacement provides good mid-term results, with a 97% survival rate at three years, comparable to other patellofemoral joint replacements [9,15], improvement in pain and with no cases of patellar maltracking despite not performing any lateral releases. Various other studies have evaluated the Avon patellofemoral joint replacement (Stryker Howmedica, Osteonics, Allendale, New Jersey). Ackroyd et al. [15] published their results from the designer institution and found mean improvements in OKS from 18 to 39, and a 96% survivorship in their series of 83 knees with a five-year follow-up. One patient had a maltracking patella which required soft-tissue realignment. Odumenya et al. [9] and Starks [16] found similar results in their series from independent centres with significant gains in OKS with only one requiring subsequent lateral release for persistent patellar instability. Our results were similar, with improvements in Oxford Knee Scores from 19.7 pre-operatively to 32.1 at one year and 37.7 at latest follow-up. The mean range of motion was unchanged before and after surgery, which is in keeping with other studies. Outcomes of clinical studies are summarised in Table 1. Despite the FPV replacement increasing in popularity and now being the second most used PFJ replacement in the UK [6], only one other study has evaluated its outcome. Mohammed et al. [17] reviewed 91 patients who underwent 101 PFJ replacements using three different implants (FPV, Avon, Lubinus), with only 30 having the FPV implant at a mean of 48 months follow-up. It is important to note that despite a mean follow-up of 48 months; they implanted Lubinus implants initially before abandoning it due to high failure rates, to only later implant FPV or Avon PFJ replacements, indicating that the follow-up for FPV may have been significantly shorter. Furthermore, their results were not stratified according to implant design, and there was no objective pre- or post-operative scoring criterion (e.g., OKS) making assessment of the FPV implant difficult. Up to 32% of patients required procedures for maltracking patellae (lateral release 23% & tibial tuberosity transfer 9%). Only two (6%) FPVs required further procedures (arthroscopic debridement), compared with 24% and 43% for the Avon and Lubinus respectively. Importantly no FPVs required lateral releases. A key difference of the FPV over other patellofemoral implants is a larger component sulcus angle of 140° (Fig. 2) compared with 125° and 110° for the Avon and Lubinus implants respectively and more closely mimics the normal knee which is approximately 138°–140°
Fig. 2. Large trochlea sulcus angle of 140° closer mimics normal anatomy.
[18,19] (Fig. 2). Monk et al. [10] compared the kinematics of the FPV prosthesis with the normal knee by assessing the relationship between patella tendon angle (PTA) and knee flexion angle (KFA). They found no differences between the two groups, except at 50° of knee flexion. This contrasts with the Avon prosthesis where there were significant differences from 0° to 90° of knee flexion [20]. Furthermore, the patella and trochlea are both facetted allowing a greater contact area. In contrast, the Avon prosthesis has a dome-shaped patella, which allows point contact with a flatter broad based trochlea. Congruity between the patella and trochlea is ensured by using a patellar clamp which allows selfalignment prior to definitive fixation. We believe these are the reasons that no patients had maltracking patellae at follow-up and none required intra-operative lateral releases in our series. The main benefits of patellofemoral joint replacement over TKR include preservation of bone stock and maintenance of the normal tibiofemoral joint and surrounding ligaments and soft tissues. This allows for a less invasive surgical procedure, faster recovery and a more simple revision to TKR if needed. A recent study by Lonner et al. [21] found that the results of TKR after failed patellofemoral replacement were not compromised. Our results reflect this with our 1 patient who underwent revision having a satisfactory outcome. The main concern of patellofemoral joint replacement is progression of tibiofemoral osteoarthritis, therefore making correct patient selection extremely
Table 1 Summary of outcomes of Avon and FPV PFJR. Author
PFJ Implant
No. of cases
Age (years)
Follow-up (months)
Outcomes
Flexion before and after
Complications/further procedures
Al-Hadithy
FPV
49
62
37
120°–120°
Mohammed et al. [17]
Lubinus FPV Avon
46 30 25
57
48
Pre-op OKS 19.7 Post OP OKS 37.7 73% did very well —authors subjective assessment
Starks [16]
Avon
37
66
24
Post op OKS 39
Not stated
Leadbetter [24]
Avon
79
58
36
13 clinical failures
Not stated
Ackroyd et al. [15]
Avon
90
68
62
Pre-op OKS – 18 Post op OKS 39
113°–115°
Odumenya et al. [9]
Avon
50
66
64
Post op OKS 30.5
120°–120°
2 Revision to TKR 1 Arthroscopic debridement 18 Arthroscopic debridement 8 Lateral release 3 Tibial tuberosity transfer 4 Revision to TKR 1 Staged patella resurfacing 1 Patella fracture 1 Patella tendon rupture 1 Tibial tuberosity fracture 1 Arthrofibrosis 2 Arthroscopic evacuation of haematoma 1 Manipulation for stiffness 1 Patella instability required distal soft tissue realignment 4 revision for progression of OA 7 Lateral subluxation 1 Lateral release Not stated number of intra-operative lateral releases
OKS = Oxford Knee Score, KSS = Knee Society Score, OA = osteoarthritis
25% lost last 10° of flexion, and 5% lost 5° of extension
N. Al-Hadithy et al. / The Knee 21 (2014) 138–141
important. The progression of tibiofemoral osteoarthritis ranges from 12% to 24% depending on follow-up duration [22,23]. We had 6 cases (12%) of radiological progression of tibiofemoral osteoarthritis. One patient was revised to bilateral TKRs; however, in retrospect, we attribute this to poor patient selection as lateral compartment degenerative changes were seen on the immediate postoperative radiographs. We are now considering the routine use of Schuss views in addition to standing anteroposterior, lateral and skyline views in all patients being considered for PFJ replacements. We acknowledge the limitations of this study being retrospective and without randomisation. Measurement bias was minimised by having two independent assessors who were not involved with the original operations and by blinding the operating surgeons to the assessment. We conclude that the FPV patellofemoral joint replacement appears to be a reliable prosthesis in patients with isolated patellofemoral osteoarthritis, which at a mean follow-up of three years, has a high survival rate, provides gives good pain relief, with high functional scores and reliably allows normal patellar tracking without the need for an extensive lateral release. 8. Conflict of interest The authors certify that we have no commercial associations (e.g., employment, consultations, stock ownership, honoria, paid expert testimony, patent applications/registrations, and grants or other funding, etc) that might pose a conflict of interest in connection with the submitted article. References [1] Davies AP, Vince AS, Shepstone L, Donell ST, Glasgow MM. The radiologic prevalence of patellofemoral osteoarthritis. Clin Orthop Relat Res 2002;402:206–12. [2] Yercan HS, Ait Si Selmi T, Neyret P. The treatment of patellofemoral osteoarthritis with partial lateral facetectomy. Clin Orthop Relat Res Jul 2005;436:14–9. [3] Aderinto J, Cobb AG. Lateral release for patellofemoral arthritis. Arthroscopy Apr 2002;18(4):399–403. [4] Minas T, Bryant TRN. The role of autologous chondrocyte implantation in the patellofemoral joint. Clin Orthop Relat Res Jul 2005;436:30–9.
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