Purpose: The purpose of this study was to determine the clinical and radiographic outcomes at a minimum follow-up of ten years of patients who underwent a total knee arthroplasty with an inset patellar component. The incidence of anterior knee pain and the factors which may contribute to were also studied.

Method: Patients who had genesis I/II TKA with an inset patellar button with a minimum follow-up of 10 years were identified. 448 patients with 521 knees were identified. Patients were excluded if they were deceased, had incomplete data, were unable to be contacted or had a known or impending revision. Those who had revision were included in a Kaplan-Meier survivorship analysis. The included patients, deceased patients and those lost to follow-up were named group1, 2, and 3 respectively. Demographics and Knee society scores(KSS) were studies for all 3 groups. This was to identify any exclusion bias. Presence and severity of anterior knee pain as well as radiographic factors were collected for group 3. Logistic regression analysis was used to identify and variables that influenced the KSS and presence of anterior knee pain. Kaplan-Meier survivorship analysis was performed for patellar revision and tibial/femoral revision endpoints.

Results: 144 patients with 175 TKA were included in this study. They were on average 66 years old, 64% female, had a BMI of 30 and had a diagnosis of OA 92% of the time. Their average f/u was 11.3 years. Groups 2 and 3 had similar demographics but of course a much shorter f/u. Group 1 had a pre-op KSS of 84 a post-op KSS of 151 and a KS change score of 67. Groups 2 and 3 had similar pre-op, post-op and KSS change scores. We found anterior knee pain occurred in 5% of patients with an average severity of 5/10. Linear regression analysis did not identify any variables including radiographic parameters that had an independent influence on KSS or anterior knee pain. Kaplan-Meier survivorship with patellar revision for any reason as an endpoint was 96% at 10 years and 94% at 17 years. 20 patella were known to have had a revision or were undergoing a revision.

Conclusion: We conclude that use of an inset patellar component can give excellent durable results over time with a low rate of anterior knee pain and complications