Patellofemoral Arthroplasty

Abstract

Background: Patellofemoral arthritis is a common cause of anterior knee pain and limits flexion-related activities of daily living and exercise. While frequently present in bicompartmental and tricompartmental osteoarthritis, patellofemoral arthritis can occur in isolation. Patellofemoral arthroplasty as a treatment option is gaining in popularity, especially with new implant designs. We report a case in which new inlay implants were used to resurface the patellofemoral joint in a patient with contralateral compromise secondary to a previous below-knee amputation.

Case report: A 37-year-old female with a contralateral right below-knee amputation and progressive left patellofemoral arthritis had failed multiple conservative treatment modalities. She underwent isolated patellofemoral arthroplasty using an inlay-designed implant. The patient was followed for 2 years postoperatively. She noticed an immediate increase in her knee range of motion and her pain scores improved. Two years postoperatively, she demonstrated drastic improvement in all outcome measures: International Knee Documentation Committee score (16.1 to 88.5), Lysholm Knee Scoring Scale (22 to 100), Knee Injury and Osteoarthritis Outcome Score (KOOS) Symptoms (7.14 to 96.43), KOOS Pain (2.78 to 100), KOOS Activities of Daily Living (0 to 100), KOOS Sports (0 to 100), and KOOS Quality of Life (12.5 to 93.75).

Conclusion: Inlay patellofemoral arthroplasty is a valid treatment option for isolated patellofemoral arthritis. Successful results can be achieved with this procedure after failure of conservative measures in patients with limited or no evidence of tibiofemoral arthritis.

Keywords: Amputation; arthritis; arthroplasty–replacement–knee; patellofemoral joint.

Figure 1.. Preoperative radiographs from (A) anterior-posterior, (B) lateral, and (C) Merchant views demonstrate severe left patellofemoral arthritis with preserved tibiofemoral joint spaces and a right below-knee amputation stump with open reduction internal fixation hardware in place.

Figure 2.. Intraoperative arthroscopic images demonstrate severe osteoarthritis with complete cartilage loss on the undersurface of the (A) patella and (B) the trochlea.

Figure 3.. Intraoperative images of the (A) anterior cruciate ligament, (B) medial meniscus, and (C) lateral meniscus demonstrate no concomitant pathology.

Figure 4.. Intraoperative images show (A) preparation of the trochlea, (B) final trochlear groove implant with inlayed implant lying flush with the native femoral cartilage, (C) undersurface of the patella with severe arthritis changes and complete loss of cartilage, (D) undersurface of the patella after preparation with all of the arthritic cartilage removed, and (E) final patella implant.

Figure 5.. Two years postoperatively, radiographs from (A) anterior-posterior, (B) lateral, and (C) Merchant views demonstrate patellofemoral arthroplasty implants in good position with excellent patellofemoral tracking.