Trochlear resurfacing for extensor mechanism instability following patellectomy

Patellofemoral Arthroplasty

Background

The first report of patellofemoral arthroplasty (PFA) was published in 1979¹. Reviews in 2005 and 2007^2,3 called for studies comparing PFA with total knee arthroplasty (TKA) for isolated patellofemoral osteoarthritis. A blinded randomized controlled trial (RCT) was initiated in 2007 for this purpose, and the first report with 2-year results was awarded the Mark Coventry Award of the Knee Society in 2017⁴. It was found that (1) patients recover more quickly from PFA than from TKA; (2) during the first 2 years after surgery, PFA-treated patients have better average knee function than TKA-treated patients; and (3) PFA-treated patients regain their preoperative range of movement within the first postoperative year whereas TKA-treated patients do not regain it within the first 2 years⁴.

Description

There are general principles that are common to all brands of PFA implants. These include (1) an indication based on bone-on-bone contact in the patellofemoral joint with a preserved tibiofemoral joint; (2) replacing all surfaces of the patellofemoral joint, with metal on the femoral side and polyethylene on the patellar side; (3) ensuring a smooth transition from normal articular cartilage to the trochlear component; and (4) creating normal patellofemoral tracking.

Alternatives

The primary treatment of any degenerative condition should be nonoperative, but when such measures are insufficient surgical treatment may be indicated. Many procedures have been suggested for relieving patellofemoral pain, but if there is bone-on-bone contact in the patellofemoral joint, the only current surgical option (except for experimental treatments) is joint replacement-i.e., either PFA or TKA.

Rationale

Our general principle for joint replacement of the knee is to replace only the affected compartment if unicompartmental changes are found. If ≥2 compartments are affected, we perform TKA. This principle is challenged both by proponents of performing TKA in all cases of knee osteoarthritis and by proponents of bicompartmental knee replacement for 2-compartment disease. The 2-year results of our blinded RCT comparing PFA and TKA⁴ support our current practice of PFA. In our practice, we have found PFA to be a rewarding procedure when the correct indications are used. PFA is likely to remain a fairly rare procedure, but any knee arthroplasty center should be able to offer it.

Medial Quadriceps Tendon Femoral Ligament Reconstruction After Patellectomy: A Treatment for a Dislocating Quadriceps Tendon

The medial quadriceps tendon femoral ligament (MQTFL) reconstruction is an alternative to the patellar bony fixation of the medial patellofemoral ligament reconstruction for the treatment of lateral patellofemoral dislocation. We describe the first report of a unique application of this technique in a patient with a previous patellectomy to treat a dislocating quadriceps tendon. An active 59-year-old Caucasian man presented 25 years after patellectomy with a dislocating quadriceps tendon and significant dysfunction. Stabilization of the knee extensor mechanism with an MQTFL reconstruction and retensioning of the quadriceps complex by tibial tubercle distalization provided stability and improved function. Extensor tendon instability is a rare complication after patellectomy that can cause significant pain and dysfunction. Successful stabilization of the quadriceps mechanism through an MQTFL reconstruction can provide excellent patient satisfaction and functional results. This technique may have implications for patellofemoral instability surgeries and in cases of knee extensor dysfunction after total knee arthroplasty.

Total patellectomy in knees without prior arthroplasty: a systematic review

PURPOSE

Total patellectomy is a radical procedure and is only used as a last resort. The functional results reported in the literature are contradictory. The purpose of this review of the literature is to evaluate the functional outcome that can be expected after total patellectomy.

METHODS

The systematic review was conducted in accordance with the PRISMA statement criteria using the PubMed/MEDLINE database, the EMBASE database, the Cochrane library databases, and the OVID database. Patellectomies were performed either alone or in conjunction with reinforcement of the extensor mechanism; they were longitudinal or transverse. Analysis was first descriptive and then comparative based on medians.

RESULTS

Research identified 394 articles, of which 31 have been included in this review, describing a total of 1,416 knees with a mean follow-up of 7 years. The mean percentage of outcomes judged good or excellent per article was 68.8% (min-max: 29-100%). The complication rate identified was 20.3% (7.6% without calcifications). The functional outcome was considered better in the group undergoing reinforcement of the extensor mechanism [median of percentages per article at 93, IQR = (74-95) vs. 67 (55-79) in the group patellectomy alone].

CONCLUSION

Total patellectomy gives good or excellent results in 85% of cases if reinforcement is performed with a longitudinal excision.

LEVEL OF EVIDENCE

IV.

Knee replacement for osteoarthritis secondary to chronic patellar dislocation and trochlear dysplasia

Fifteen knees in patients suffering from symptomatic osteoarthritis secondary to chronically dislocated extensor mechanisms have been treated by knee replacement. Five knees had permanently dislocated patellae while 10 knees (four of which had undergone patellectomies) had dislocations of the extensor mechanisms with knee flexion. In fourteen instances satisfactory realignment of the extensor mechanism was obtained. In twelve knees, a substantial functional improvement was achieved. Two knees had persistent pain and one had unexpected tibio-femoral instability.

Patellofemoral arthroplasty in the treatment of patellofemoral arthritis: rationale and outcomes in younger patients

Patellofemoral degenerative disease encompasses a spectrum of articular wear from severe chondrosis to advanced arthrosis. The rationale and timing for many operative approaches currently advocated for the relief of symptomatic patellofemoral degeneration can be the subject of intense surgical debate in any one patient. Unfortunately, the limited efficacy of many commonly advocated operative procedures has left a legacy of patellofemoral disability in many younger individuals. While total knee arthroplasty has an established role in the treatment of advanced patellofemoral arthritis in the older patient (age >60 years), the performance of what some have called "a knee joint amputation" in younger patients (age <45 years) remains controversial and less acceptable to patients. The Avon patellofemoral prosthesis is a second-generation knee joint-conserving device that has consistently achieved good to excellent results in both the primary treatment and salvage of patellofemoral degenerative disease in younger patients. In addition, patellofemoral arthroplasty has demonstrated success as a unique functional, tibial-femoral joint-conserving solution in a variety of other patellofemoral extensor mechanism problems.

The use of a tantalum-based Augmentation Patella in patients with a previous patellectomy

Patients with previous patellectomies for anterior knee pain syndrome, can remain symptomatic and develop osteoarthrosis or instability. We report our experience of the use of a novel implant to substitute for the absent native patella. Seven patients, with previous patellectomies, were treated with the Augmentation Patella (Zimmer, Allendale, USA). This implant was sutured to the patellar tendon, as part of a patello-femoral joint replacement (four cases) or total knee replacement (three cases). In three patients, the implant loosened and failed within 15 months. Two patients remained symptomatic despite solid fixation. One patient developed wound complications due to the bulk of the implant, and the procedure was abandoned in one patient as wound closure was not possible. The results of this implant in our patients with previous patellectomies have been disappointing. Previous studies where this implant has been used, have also shown high loosening and failure rates. We do not recommend its use to substitute for the absent patella.

The Avon patellofemoral arthroplasty: five-year survivorship and functional results

We report the mid-term results of a new patellofemoral arthroplasty for established isolated patellofemoral arthritis. We have reviewed the experience of 109 consecutive patellofemoral resurfacing arthroplasties in 85 patients who were followed up for at least five years. The five-year survival rate, with revision as the endpoint, was 95.8% (95% confidence interval 91.8% to 99.8%). There were no cases of loosening of the prosthesis. At five years the median Bristol pain score improved from 15 of 40 points (interquartile range 5 to 20) pre-operatively, to 35 (interquartile range 20 to 40), the median Melbourne score from 10 of 30 points (interquartile range 6 to 15) to 25 (interquartile range 20 to 29), and the median Oxford score from 18 of 48 points (interquartile range 13 to 24) to 39 (interquartile range 24 to 45). Successful results, judged on a Bristol pain score of at least 20 at five years, occurred in 80% (66) of knees. The main complication was radiological progression of arthritis, which occurred in 25 patients (28%) and emphasises the importance of the careful selection of patients. These results give increased confidence in the use of patellofemoral arthroplasty.