A Rare Cause of Anterior Knee Pain in a Young Athlete and a Delayed Diagnosis: Osteoid Osteoma of the Patella

Intra-articular osteoid osteomas are a rare cause of articular pain. Their diagnosis can be challenging due to their non-specific clinical presentation and imaging characteristics. We present the case of a young soccer player with a 12-month history of anterior knee pain that was first attributed to Sinding Larsen Johansson syndrome and then to Hoffa's syndrome. A CT scan was performed that revealed the localization of an osteoid osteoma of the patella. The patient was successfully treated by percutaneous radiofrequency ablation under CT guidance without complications and returned to full sports activity. Although a rare entity, osteoid osteoma of the patella with its atypical clinical features could be included in the differential diagnosis of persistent anterior knee pain in the young adult. High clinical suspicion is necessary to avoid delay in diagnosis and irrelevant procedures for the patient.