Page 20 - ISAKOS Newsletter 2016 Volume 1

CURRENT CONCEPTS
Patellar Resurfacing: Where Are We Now?
Current Literature
Since the patellar resurfacing discussion has be ongoing for over 30 years, there are literally hundreds of articles on the topic. The studies, reviews and meta-analysis published in the last five years continue to be inconclusive. In 2011, Breeman et al published a randomized controlled trial of 1,715 patients randomized to resurfacing vs. non-resurfacing with five year follow-up and found no difference in functional outcomes, reoperation rate or total health care costs. Two percent of the patients that were in the non-resurfaced group required secondary resurfacing within five years, and one percent of the patients undergoing resurfacing sustained a patellar related complication that required revision surgery. Pavlou et al performed a meta-analysis also published in 2011 which showed that patellar resurfacing did not significantly affect anterior knee pain or functional outcomes; however, there was a slightly higher reoperation rate in the non-resurfaced group. Another meta-analysis also published in 2011 by Li et al, reported that the risk of reoperation due to patello-femoral pain was reduced by patellar resurfacing; however, there was no difference in pain and knee function between the two groups. In 2012, Beaupre et al reported the results of another randomized controlled trial with 5–10 year follow-up and showed no difference between the resurface and non-resurfaced groups. A meta-analysis in 2012 published by Pilling et al found that patellar resurfacing decreased the risk of reoperation due to patello-femoral pain, but otherwise no difference in patient satisfaction, pain or function was noted between the two groups. However, it is important to note that in the resurfaced group anterior knee pain was 11% less than in the non-resurfaced group. Chen et al published another meta-analysis in 2013 that found that the absolute risk of reoperation was reduced by 4% in the patellar resurfacing arm; meaning that one would have to resurface 25 patellae to prevent one reoperation. There was no difference in groups in regard to anterior knee pain, knee pain score and knee function score.
Controversy / Consensus
The biggest problem in the resurfacing vs. non- resurfacing debate is not understanding why some patients have post-operative anterior knee pain and others do not. This is the driving force behind the selective resurfacing argument. In 2001 Barrack et al found that 28% of patients with resurfaced patellae suffered from anterior knee pain post-operatively. These patients had not reported pre-operative anterior knee pain. 9% of patients that reported pre-operative anterior knee pain had continued pain post-operatively despite resurfacing. In the non- resurfaced group, 23% reported anterior knee pain pre-operatively and continued to report similar pain post-operatively; 14% of the non-resurfaced group developed new anterior knee pain post-operatively.
Despite the variation in outcomes with and without resurfacing, there is some consensus regarding patients that should undergo resurfacing at the time of primary total knee arthroplasty, these include patients with inflammatory arthritis, severe patellar deformity or eburnation, and the presence of crystalline disease.
Conclusions
Despite 30 years of research into patellar resurfacing, answers remain elusive. North American surgeons continue to be the most aggressive in patellar resurfacing, with Europeans in general being less likely to resurface, with wide variations from country to country. Most data point to similar outcomes with resurfaced and non-resurfaced patellae; however, the risk of reoperation for anterior knee pain persists and is more common in non-resurfaced patellae.
Ultimately, the answer will most likely reside in selective resurfacing; however, the criteria for selective resurfacing still requires more research to determine which patients are at highest risk for post-operative anterior knee pain and would benefit from primary resurfacing. Several confounding factors may be at play in making these selection criteria elusive including vast differences in implant “patellar-friendly” design; sensitivity of the knee scoring systems to determine real differences in patient outcomes, the so called “ceiling effect”, the vast heterogeneity in data in the large meta-analysis with different implants and surgeon treatments of the patella. It appears as if the debate will continue for years to come, until further research and analysis can bring clarity to the appropriate patient for resurfacing vs. non-resurfacing.
18 ISAKOS NEWSLETTER 2016: Volume I