A, Dislocation of metacarpophalangeal (MCP) joint of thumb. Metacarpal head has penetrated joint capsule; if traction were applied to thumb, metacarpal neck would be caught by capsule and reduction would be impossible. Traction should not be applied; rather, metacarpal should be adducted and dislocated joint should be hyperextended, while proximal end of proximal phalanx is pushed against and over metacarpal head with interphalangeal joint flexed to reduce tension on flexor pollicis longus. B, Clinical appearance of sports-related complex dorsal thumb MCP joint dislocation in a 15-year-old boy. C and D, Lateral and posteroanterior images of thumb prior to open reduction.