Osgood-Schlatter Disease (OSD) is inflammation of the patellar ligament at the tibial tuberosity (apophysitis). It is characterized by a painful bump just below the knee that is worse with activity and better with rest. Episodes of pain typically last a few weeks to months. One or both knees may be affected and flares may recur.
Risk factors include overuse, especially sports which involve frequent running or jumping. The underlying mechanism is repeated tension on the growth plate of the upper tibia. Diagnosis is typically based on the symptoms. A plain X-ray may be either normal or show fragmentation in the attachment area.