Musculoskeletal Injuries and Conditions
Core concepts
Know the anatomy and mechanism of the high-yield injuries: ankle sprain (inversion, ATFL first), ACL tear (noncontact pivot, hemarthrosis, positive Lachman most sensitive), meniscal tear (twisting with planted foot, joint-line tenderness, McMurray), rotator cuff tendinopathy vs impingement, lateral epicondylitis, plantar fasciitis, and stress fractures (tibia, metatarsal, femoral neck, navicular). Understand the Ottawa ankle and knee rules as decision aids, not absolutes. Distinguish acute injury from overuse tendinopathy; the latter is degenerative, not purely inflammatory, which drives load-management treatment.
Traps
Questions love mechanism-to-structure pairings: inversion = lateral ligaments, eversion = deltoid/deltoid ligament and syndesmosis. A high ankle sprain (syndesmosis) has tenderness above the joint line and a positive squeeze test-do not call it a routine sprain. Femoral neck and navicular stress fractures are high-risk (avascular necrosis, nonunion) and need aggressive imaging and referral, unlike low-risk metatarsal or tibial shaft stress fractures. Distinguish patellofemoral pain (diffuse anterior knee, worse with stairs/sitting) from patellar tendinopathy (focal inferior pole tenderness).
Rule of thumb
For a joint with acute swelling within hours, think hemarthrosis (ACL, osteochondral fracture, or fracture) rather than a simple sprain. For stress fractures, "high-risk" sites are the femoral neck, anterior tibial cortex, navicular, fifth metatarsal base (Jones), and medial malleolus-these warrant non-weight-bearing and orthopedic input.
Worked example
A 16-year-old soccer player twists a planted knee, hears a pop, and has a tense effusion within 2 hours with a positive Lachman. This is an ACL tear with hemarthrosis; urgent orthopedic referral and protected weight-bearing are appropriate, not a "wait and see" ankle-sprain approach.