The second most commonly implanted total knee in the Swedish Knee Registry had the lowest risk ratio—0.44. But only when it was not resurfaced. That’s half the revision rate of all the knees. The best performing implants in the Swedish Knee Registry, over 90% of the knees, are not resurfaced.
So, if you are concerned with the incidence of reoperation and anterior knee pain being higher, why not resurface routinely? Well, a lot of things can go wrong. And these things all do go wrong – loosening, fracture, fragmentation, AVN, restricted motion. Ritter’s group published a paper which documented fragmentation in 4% over three years (Clin Orthop, 2001). Oblique resurfacing…20 years ago they reported at the Mayo Clinic 7% of cases have oblique resurfacing, half required knee reoperations (Pagnano, et al., Clin Orthop, 1999).
You can make it too thick; you can make it too thin.
The problem is it’s the last step in a total knee. The instrumentation is variable. And the complications are underreported. There are a lot of advantages to not resurfacing the patella. It’s faster. It’s less expensive. Lower risk of major complications. If a problem does develop you have a lot more options. End results are very similar.
A little know trend in meta-analyses and registry reviews that I’m sure you’ll hear from Steve Haas, is that there is tremendous variability and discretion involved in the methodology. Studies have shown that the results agree with the practice patterns of the authors over 100% of the time. It’s best to rely on impartial sources of data, like the AAOS Clinical Practice Guidelines. And they say that there is strong evidence that pain and function are the same. There’s moderate evidence that the reoperation rate is higher, but that’s only because the reoperation rate for resurfacing is underreported.
Now in the Swedish Registry, at 10 years, the reoperation rate is higher in resurfaced patellae (Fraser, et al., JOA, 2017).
So, in conclusion, this continues to be a highly debated topic. You can get good results from either. U.S. is an outlier in the world. Most surgeons resurface the patella. Outside the U.S. most surgeons do not. The difference, if it exists at all, is very small and I predict that the fastest trend that we’ll see in the next decade is cementless knees without patella resurfacing.
