Arthroscopic Piecemeal Excision of a Large Intra-articular Infrapatellar Osteochondroma of the Knee: A Case Report.

Abstract

Introduction: Intra-articular osteochondromas are uncommon mass-occupying lesions of the knee, with a reported prevalence of approximately 1 in 1 million. Large lesions in the infrapatellar region are exceptionally rare, and only a handful of cases have been described in the literature. Based on a comprehensive review of the English literature, to the best of our knowledge, we report what appears to be one of the largest intra-articular infrapatellar osteochondromas successfully excised using a minimally invasive arthroscopic technique.

Case report: A 46-year-old Filipino female presented with a 6-month history of progressive pain, swelling, and restriction of motion in the left knee. Imaging revealed a well-defined ossified mass in the infrapatellar region measuring approximately 28 × 20 mm - comparable in size to the native patella. The lesion was excised arthroscopically in a piecemeal fashion followed by retrieval through a mini-open medial parapatellar incision. Histopathological examination confirmed the diagnosis of an osteochondroma with a hyaline cartilaginous cap.

Conclusion: This case demonstrates that large intra-articular osteochondromas of the infrapatellar region, though rare, can be safely and effectively managed with arthroscopic piecemeal excision, facilitating early rehabilitation and avoiding the morbidity of open surgery. The presence or absence of synovial tissue within the lesion helps determine the etiology and malignant potential, although transformation remains rare.