BACKGROUND:
Surgeons may "usually" resurface the patella during total knee arthroplasty (TKA), "rarely" resurface, or "selectively" resurface on the basis of certain criteria. It is unknown which of these 3 strategies yields superior outcomes. Utilizing New Zealand Joint Registry data, we investigated (1) what proportion of surgeons employs each of the 3 patellar resurfacing strategies, (2) which strategy is associated with the lowest overall revision rate, and (3) which strategy is associated with the highest 6-month and 5-year Oxford Knee Score (OKS).

METHODS:
Two hundred and three surgeons who performed a total of 57,766 primary TKAs from 1999 to 2015 were categorized into the 3 surgeon strategies on the basis of how often they resurfaced the patella during primary total knee arthroplasty; with "rarely" defined as < 10% of the time, "selectively" as ≥10% to ≤90%, and "usually" as >90%. For each strategy, the cumulative incidence of all-cause revision was calculated and utilized to construct Kaplan-Meier survival curves. The mean 6-month and 5-year postoperative OKS for each group were utilized for comparison.

RESULTS:
Overall, 57% of surgeons selectively resurfaced, 37% rarely resurfaced, and 7% usually resurfaced. The usually resurfacing group was associated with the highest mean OKS at both 6 months (38.57; p < 0.001) and 5 years postoperatively (41.34; p = 0.029), followed by the selectively resurfacing group (6-month OKS, 37.79; 5-year OKS, 40.87) and the rarely resurfacing group (6-month OKS, 36.92; 5-year OKS, 40.02). Overall, there was no difference in the revision rate per 100 component years among the rarely (0.46), selectively (0.52), or usually (0.46) resurfacing groups (p = 0.587). Posterior-stabilized TKAs that were performed by surgeons who selectively resurfaced had a lower revision rate (0.54) than those by surgeons who usually resurfaced (0.64) or rarely resurfaced (0.74; p < 0.001).

CONCLUSIONS:
Usually resurfacing the patella was associated with improved patient-reported outcomes, but there was no difference in overall revision rates among the 3 strategies.

LEVEL OF EVIDENCE:
Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.





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