Evaluation of the anatomic patellar prosthesis in uncemented porous-coated total knee arthroplasty: seven-year results.

We studied 41 patients (56 knees; mean patient age, 55.3 years) who were followed up for a minimum of 7 years (range, 84 to 90 months) after primary resurfacing arthroplasty of the patella with an anatomic patellar prosthesis during uncemented porous-coated anatomic total knee arthroplasty. The operative diagnosis was osteoarthritis in 33 knees; rheumatoid arthritis in 16; tuberculous arthritis in 4; posttraumatic arthritis in 2; and ankylosis in 1. The average preoperative Hospital for Special Surgery knee score was 33 points (range, 10 to 69 points), which improved to 81 points (range, 54 to 100 points) at the final follow-up examination. There was a high rate of component loosening (23 knees or 41%). A total of 27 of 33 solidly fixed patellar prostheses (82%) had osteolysis in the patella. Forty-two knees (75%) had wear of the tibial polyethylene liners; a mean of 2.5 mm in the medial compartment and 1.7 mm in the lateral compartment. Our experience does not support the continued use of this prosthesis.