🦴 Apophysitis (Overuse)
• Osgood-Schlatter: tibial tubercle (patellar tendon insertion), age 10-15, bilateral in 20-30%, worse with running/jumping/kneeling
• Sinding-Larsen-Johansson: inferior pole of patella, similar presentation
• Sever disease: calcaneal apophysitis (heel pain)
🩺 Anterior Knee Pain
• Patellofemoral pain syndrome: vague anterior pain, worse with stairs/squatting/sitting (theater sign)
• Patellar subluxation/dislocation: apprehension test positive, locked knee (≈45° flexion)
• Bipartite patella: incidental x-ray finding, may become painful
🦵 Ligamentous & Meniscal Injuries
• ACL tear: twisting injury, "pop," immediate hemarthrosis (hours)
• Meniscal tear: twisting with foot planted, delayed effusion (24-48h), joint line tenderness, locking
• PCL, MCL, LCL: less common but possible
⚠️ Other Causes
• Osteochondritis dissecans (OCD): avascular necrosis of femoral condyle (medial > lateral), locking, loose body
• Discoid meniscus: lateral congenital variant, "clunk" with flexion
• SCFE/hip pathology: referred pain to knee → examine hips!
• Septic arthritis: fever, effusion, refusal to bear weight
📌 Decision strategy: Anterior knee pain in adolescent athlete → apophysitis or patellofemoral. Effusion immediate after trauma → hemarthrosis (ACL tear). Delayed effusion → meniscal tear. Hip pathology can present as knee pain → always check hip exam.