This history is typical of Osgood-Schlatter disease. Microfractures in the area of the insertion of the patellar tendon into the tibial tubercle are common in athletic adolescents. Swelling, tenderness, and an increase in size of the tibial tuberosity are found. Radiographs can be used to rule out other conditions. Treatment consists of rest.Legg-Calve-Perthes disease is avascular necrosis of the femoral head. This condition usually produces mild or intermittent pain in the anterior thigh but can also present as a painless limp. Gonococcal arthritis, although common in this age range, is uncommon in this anatomic site. More significant systemic signs and symptoms, including chills, fever, migratory polyarthralgia, and rash, are commonly seen. Slipped capital femoral epiphysis is usually seen in a younger, more obese child (mean age about 10 years) or in a thinner, older child who has just undergone a rapid growth spurt. Pain upon movement of the hip is typical. Popliteal (Baker) cysts are found on the posterior aspect of the knee. Observation is usually all that is necessary, as they typically resolve over several years. Surgical excision is indicated if the cyst progressively enlarges or if there are unacceptable symptoms associated with the cyst.