Recurrent giant cell tumor of the patella managed by total patellectomy and Achilles tendon allograft reconstruction: a case report and review of the literature

Introduction and importance: Primary tumors of the patella are rare, accounting for less than 1% of primary bone tumors of the lower extremity. Giant cell tumor (GCT) is a locally aggressive, benign bone tumor causing progressive bone destruction. While primary management often involves curettage, treating local recurrence is complex, necessitating a balance between oncological clearance and functional preservation. Presentation of case: A 22-year-old male presented with a 6-month history of knee pain and swelling. He had undergone curettage and bone grafting for a patellar GCT 2 years prior. Evaluation confirmed a local recurrence with soft-tissue extension (Campanacci grade III). He was successfully treated with a total patellectomy and reconstruction of the extensor mechanism using a frozen Achilles tendon allograft. Clinical discussion: Local recurrence of patellar GCT demands more radical surgical intervention than the primary lesion. Total patellectomy provides definitive oncological resection but results in the loss of the patellar lever arm. In this patient, reconstructing the extensor apparatus with an Achilles tendon allograft restored knee stability and extension strength. At 3-year follow-up, he achieved a final range of motion of 0°–125°, no extension lag and an musculoskeletal tumor society score of 93%. Conclusion: In cases of significant local recurrence, total patellectomy followed by allograft reconstruction represents a viable surgical option to achieve local control while allowing a return to functional activity. The main takeaway lessons are: (1) GCT of the patella is a rare entity but can be an important differential diagnosis for anterior knee pain. (2) Local recurrence is a significant risk following intralesional curettage of patellar GCT. (3) In this patient, total patellectomy achieved local control of a Campanacci grade III recurrence with soft tissue extension.