ABSTRACT Introduction Unicompartmental knee arthroplasty (UKA) is a treatment option in patients with unicompartmental degenerative disease. Compared to total knee arthroplasty (TKA), the advantages of UKA include accelerated recovery and cruciate ligament retention. These advantages, along with emerging evidence that mild patellofemoral joint osteoarthritis does not compromise results of UKA have encouraged expansion of the indications for UKA. Symptomatic lateral patellofemoral joint degenerative disease is a common cause of UKA revision. Partial lateral patellar facetectomy can provide relief from symptoms of lateral patellofemoral degenerative disease. We hypothesize that simultaneous UKA and lateral patellar facetectomy provides durable pain relief and functional improvement in a patient population with degenerative disease of one tibiofemoral compartment and the lateral patellofemoral joint. Materials and methods: Between 2004 and 2008, 11 lateral UKA's were performed in association with partial lateral patellar facetectomy in 11 female patients (mean age: 66.7 years) with degenerative changes in one tibiofemoral compartment and the lateral patellofemoral joint. Patients were followed clinically and radiographically for a mean of 5 years. Results No patient underwent revision surgery in the followup period. The mean international Knee Society (IKS) knee score improved from 64.9 ± 11.2 points preoperatively to 87.5 ± 12.6 points at final follow-up (p = 0.01). The mean IKS functional score improved from 65.9 ± 23.5 points preoperatively to 83.2 ± 23.3 points at final follow-up (p = 0.012). The mean Kujala score was 84.3 ± 13.5 points postoperatively. Progression of patellofemoral OA was observed in one patient. Conclusion Simultaneous UKA and partial lateral patellar facetectomy is a viable treatment option for symptomatic degenerative disease involving one tibiofemoral compartment and the lateral patellofemoral joint. This treatment approach may be a useful alternative to TKA or bicompartmental arthroplasty in a carefully selected patient population. Level of evidence Case series—Level IV. Magnussen RA, Gancel E, Servien E, Jacobi M, Demey G, Neyret P, Lustig S. Simultaneous Unicompartmental Knee Arthroplasty and Lateral Patellar Facetectomy for Bicompartmental Degenerative Disease. The Duke Orthop J 2013;3(1):61-66.