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Long-Term Results of Kneecap Replacement

Doctors from the Aix-Marseille University in France update research they did 15 years ago. The information they gathered looks at the long-term results of patellofemoral arthroplasty (PFA) (kneecap replacement).

All the patients were adults (ages 21 to 82 years). They all had severe osteoarthritis (OA) of the patellofemoral joint. This is where the kneecap moves over the thighbone (femur). The implant was made of plastic (polyethylene), cobalt, and chromium.

About half the group still had the original implant in place 16 years later. One-fourth of this group reported moderate pain. X-rays showed the PFA was stable with no sign of loosening. Most of the other patients had further surgery over the years. Total knee replacement (TKR) was the most common operation. The patients' with primary osteoarthritis got worse requiring this next step.

The authors point out that patients who develop OA after trauma or patellar instability didn't need a joint replacement. The arthritis remained stable and didn't progress. They also found that PFA after patella fracture resulted in severe stiffness after the operation.

They conclude the PFA is a good option for middle-aged patients with good knee alignment. It should be put in place keeping in mind the possible need for future TKR. They prefer a TKR for older patients to avoid a second surgery.

References: Jean-Noël A. Argenson, MD, et al. Patellofemoral Arthroplasty. In Clinical Orthopaedics and Related Research. November 2005. Vol. 440. Pp. 50-53.

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