Introduction: The indications for patellectomy have been considerably narrowed in recent years, but there remains a cohort of patients with previous patellectomies that remain symptomatic. In addition, these patients can develop osteoarthrosis or instability, and their treatment is challenging. We report our experience of the use of a novel implant to substitute for the absent native patella.

Materials and Methods: Six patients were treated with the Augmentation Patella (Zimmer, Allendale, USA), which was sutured to the patellar tendon. All 6 patients had previously had a patellectomy for anterior knee pain syndrome or chondromalacia patellae, between 5 and 22 years previously. They all had an arthroscopy to document the extent of degenerative changes. Patients with trochlear changes only had the trochlea resurfaced (4 cases) and those with tibio-femoral changes as well had a total knee replacement (2 cases).

Results: One patient reported excellent relief of pain, with no evidence of radiological loosening. Two patients continued to complain of pain despite the implant being solidly fixed. One patient developed wound complications secondary to difficult closure due to the bulk of the implant. In two patients, the implant loosened within 15 months necessitating further surgery to retrieve the Augmentation Patella.

Discussion: The results of the Augmentation Patella in our series of patients with previous patellectomies have been disappointing. Previous studies, where this implant has been used with a remaining shell of patella, has yielded better results. This suggests that bony ingrowth is important for a successful outcome. We recommend that this device should only be implanted if bony contact is possible.