When a knee joint is replaced, you may or may not keep your own kneecap (patella). Sometimes the patella is too worn or brittle to work smoothly with the new implant.
If the doctor sees that the patella can be kept, the next decision is whether to smooth the backside. This is called patellar resurfacing. Shaving the patella may reduce painful symptoms, but there is a risk of problems. Patellar resurfacing can cause fracture or dislocation of the kneecap. The muscle that attaches to the patella (called the quadriceps muscle) can also get injured.
Right now, doctors have three choices: resurface every patella, never resurface, or only resurface when it’s truly needed. Resurfacing is always advised when rheumatoid arthritis or other problems are affecting the cartilage on the surface of the patella.
The authors of this study report no difference in outcomes between patients with and without patellar resurfacing. They studied the two groups over a period of 10 years. Pain, range of motion, walking, and stair climbing were used as measures. The main difference is that patients who had a resurfaced patella reported greater satisfaction with the results. Researchers are scratching their heads over that one. It may be that the test used to measure knee function didn’t focus on the kneecap. The survey of satisfaction did.
The bottom line is that knee joint replacement with or without patellar resurfacing reduces pain and improves function. Patients are happier with the results when the patella is smoothed out. Many doctors remain wary of the problems that can occur with resurfacing. However, this study reported a very low rate of problems.