Knee Soft Tissue Injury (ACL / MCL / Meniscus)

Mechanism: • ACL: non-contact pivot, deceleration, valgus + rotation; immediate effusion within hours; 'pop' sensation; instability ('giving way'). • MCL: valgus stress; medial pain + bruising; mild instability. • PCL: dashboard injury, hyperextension; posterior pain. • Meniscus: twisting on flexed weight-bearing knee; effusion 12–24h; locking, catching, pain on squatting. Examination: lachman test (ACL — most sensitive), anterior drawer, pivot shift; valgus stress (MCL); posterior drawer (PCL); McMurray's test (meniscus); joint line tenderness. Ottawa knee rules — XR if any: age ≥55, isolated patella tenderness, fibula head tenderness, unable to flex 90°, unable to weight-bear 4 steps. MRI gold standard for soft tissue.