Arthroscopic Excision of Solitary Intra-articular Osteochondroma of the Knee
A 41-year-old man presented with diffuse pain and discomfort in the left knee for two months. He did not report any trauma or medical problem. Physical examination revealed a palpable bony hard mass of approximately 2×2 cm in size over the superolateral aspect of the left distal femur. The skin was normal. There was no restriction in the range of movements of the knee joint, but pain was reported with over 90 degree flexion of the knee. The Lysholm score was 80, and the International Knee Documentation Committee (IKDC) score was 79 points.\nSimple radiography showed a bony mass arising from the superolateral aspect of the left distal femur without stalk (). Magnetic resonance imaging (MRI) showed a prominence with the same intensity as a bone, arising from distal femur within the joint capsule. Cortical bone was communicating into the medullary canal of the femur. A characteristic cartilaginous cap was also seen ().\nUnder general anesthesia, arthroscopic standard portals were made, and the superolateral view revealed an intra-articular cartilaginous cap. There was minimal synovitis of the joint. The cartilage cap was connected to the femur (). Ligaments, cartilage, and menisci were intact, and patellar tracking was normal in a full range of knee motion. The tumor was then excised using a small osteotomy at the supermedial portal.\nThe histopathologic report showed that the bony outgrowth was mainly a cancellous bone with a cartilaginous cap, which is a feature consistent with osteochondroma (). At one year follow-up, the patient was asymptomatic and involved in full activities. In addition, the Lysholm score and IKDC score were both 100. Radiologic follow-up revealed no recurrence ().