Patellar Resurfacing as Part of a Knee Replacement: Yes or No?Most people don't realize that a total knee replacement can involve three component parts. There is the femoral side of the joint (the bottom portion of the femur or upper thigh bone). Then there is the tibial side of the joint (the upper part of the tibia or lower leg bone). Those two components make up the main knee joint as we think about it.
But there is a third piece and that's the patella (knee cap). The patellofemoral joint (patella sliding and gliding up and down over the front of the knee) is an important part of the entire knee complex.
The question is: should the patella be resurfaced during the total knee replacement procedure? Resurfacing means the back of the patella is lined with a polyethylene (plastic) dome to allow it to move freely and smoothly once again. There is considerable debate among orthopedic surgeons about the benefits and disadvantages of patellar resurfacing.
To help sort out the question of whether or not patellar resurfacing is helpful, a meta-analysis was conducted. Researchers reviewed randomized controlled studies reported from as early as 1995 to the present time. A total of 3,465 knee replacements were included, divided evenly into two groups: those who had patellar resurfacing as part of their knee replacement and those who did not.
The three main measures of patient outcomes included: pain, function, and patient satisfaction. Other secondary results compared were rate of reoperation, complications, operative time, and X-ray findings.
There isn't much to report because except for rate of reoperation, there were no significant differences between the two groups. Pain levels after surgery, patient reported knee motion and function were the same, and 89 to 90 per cent of both groups were happy with the results. The rate of post-operative infection was low (between one and two per cent) for both groups. And the amount of time in surgery wasn't different enough to be considered significant from a statistical analysis perspective.
The only statistically significant difference between the two groups was a much higher rate of reoperation in the nonresurfaced group. Most of these second surgeries were done because of knee pain. Some of the patellar resurfacing group had to have additional surgery because of complications but the rate was much lower in the resurfacing group compared with the nonresurfacing patients.
In theory, resurfacing should take more time and increase the risk of infection. But as this study showed, in practice this just isn't the case. Most of the results from this meta-analysis don't favor routine resurfacing as part of a total knee replacement. There is not clear proof that continued knee pain in patients who did not have patellar resurfacing was really due to lack of patellar resurfacing.
No firm conclusions could be made from this meta-analysis. The authors note there are just too many other variables to consider such as changes in the design of knee implants over the years, changes in surgical technique over the same time period, and differences in surgical techniques used. The fact that patient satisfaction was equal between the two groups is significant.
In the end, the decision to resurface (or not resurface) the patella as part of the knee replacement must be made together by the patient and surgeon. Surgeons must keep up with the results of studies like this one in order to consider all the current evidence available when advising and counseling patients individually.
R. W. D. Pilling, MRCS, et al. Patellar Resurfacing in Primary Total Knee Replacement. A Meta-Analysis. In The Journal of Bone and Joint Surgery. December 19, 2012. Vol. 94A. No. 24. Pp. 2270-2279.
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