Outerbridge classification as a predictor for the need of patellar resurfacement in total knee arthroplasty: a prospective study

Background: Residual anterior knee pain after total knee arthroplasty is one of the common causes of early revision surgery in form of patellar resurfacing and even resurfacing the patella in these circumstances may not relieve the symptoms. So, the decision to perform patellar resurfacing during total knee arthroplasty to prevent anterior knee pain remains controversial. The purpose of this study is to determine if the outerbridge classification can predict the need for Patellar resurfacing as part of total knee arthroplasty.Methods: 100 patients with advanced osteoarthritis of knee fulfilling the inclusion and exclusion criteria were randomized into two groups of 50 patients each. In group A-patellar resurfacing done and in group B-patella was not resurfaced while carrying out TKR. Each patient was assessed intraoperatively and his/her patella classified as per Outerbridge classification. Patients were followed-up at 03, 06 and 12 months postoperatively and assessed by modified hospital for special surgery (HSS) knee scores.Results: In case of Outerbridge class III group there is a statistically significant difference (p value -0.002) in HSS score at 03 months, which becomes highly significant at 06 months (p value -0.001) and 01 year (p value <0.001). Similarly, there is statistically significant difference in HSS score (p value- 0.001) in Outerbridge class IV group at 03 months, 06 months and 01 year.Conclusions: Patellar resurfacing in patients undergoing total knee arthroplasty with patella in Outerbridge class III and IV can be safely carried out to further improve the functional outcome. There is no distinct advantage of resurfacing patella in Outerbridge class I and II in terms of functional gain. Thus, Outerbridge classification for patella can effectively guide us whether to resurface patella or not in patients undergoing total knee arthroplasty.