The use of patellar resurfacing has come under scrutiny many times over the years without a clear consensus about what to do. Resurfacing the patella involves shaving and smoothing the cartilage and bone along the back of the patella. Then the surface is covered with an implant made of metal, polyethylene (plastic), or a combination of both metal and polyethylene. Many surgeons favor the all-polyethylene backing as a result of studies that have shown there are fewer problems with it.
One of the reasons surgeons try to address the question of “to do” or “not to do” patellar resurfacing is related to the overall results of knee replacements. Studies show a 90 per cent survival rate of the implant. That’s great but it doesn’t say anything about how the patient is doing.
Other studies report a large number of patients have ongoing knee pain and loss of function despite the new knee. Quality of life is then affected. Could it be that something so simple as to resurface the knee cap could change that dynamic?
A recent study was done in England to see if patellar resurfacing made any real difference. It was part of a larger study investigating the results of using four different total knee replacements. The larger study is called the Knee Arthroplasty Trial (KAT).
With over 1700 patients enrolled in the KAT study, this may be the largest research project looking at patellar resurfacing. Half the patients got a knee replacement with patellar resurfacing while the other half received the knee implant but did not have the patella resurfaced.
Results were compared between the two groups using pain, motion, and function as the main measures. There are several tests that give objective data to compare. The authors used the Oxford Knee Score, the Short-Form-12, and the EuroQoL 5D. They also looked at costs and compared the number of patients in both groups who had to have a revision (second) surgery.
After all the data was in and the number crunching was done, there was no difference between the two groups. After five years, presence of pain, pain levels, and the quality of life based on knee function were about the same for all patients in both groups.
The large number of patients involved in the study help support this idea that there is no obvious benefit of patellar resurfacing at the time of the knee replacement procedure. Surgeons may want to reserve patellar resurfacing for patients who continue to experience knee pain after knee replacement. Resurfacing the patella is a simple revision procedure that can be done later if needed.