Trabecular metal augmentation for idiopathic avascular necrosis of the patella following non-resurfaced total knee arthroplasty

Avascular necrosis (AVN) of the patella is an uncommon complication following non-resurfaced total knee arthroplasty (TKA) and is typically attributed to compromised blood supply during surgery. We presented a case of idiopathic patellar AVN in a 71-year-old male one year after TKA with a non-resurfaced patella. Radiographs at that time revealed patellar erosion, prompting patelloplasty with a Zimmer NexGen Trabecular Metal Augmentation Patella (Zimmer Biomet, Warsaw, Indiana). Two weeks post-operatively, the patient resumed activities of daily living with minimal pain. At nine months, radiographs showed further patellar resorption and fragmentation, though the implant remained well-aligned. The patient exhibited no extensor lag but did present with mild weakness compared to the contralateral side. This case highlights trabecular metal patellar augmentation as a viable surgical option for managing symptomatic idiopathic patellar avascular necrosis following non-resurfaced total knee arthroplasty. The procedure preserved extensor mechanism function and provided meaningful clinical improvement, underscoring its potential role in select patients with limited patellar bone stock.