Metacarpophalangeal joint dislocation

The metacarpophalangeal joint is a biaxial joint composed of the proximal phalanx, the metacarpal head, the palmar plate, the collateral ligament, the collateral ligament, and the joint capsule. It has flexion-extension, adduction-abduction, and a certain amount of orbital rotation motion. Among them, the flexion-extension motion has the largest amplitude. Dislocation of the metacarpophalangeal joint is more common in the thumb and index finger, and rare in other fingers. Most of them are dislocations on the palm side, and dorsal dislocations are rare. Usually the fingers are in an overstretched position, and the violence from the longitudinal direction causes the palmar joint capsule of the metacarpophalangeal joint to rupture and the palmar fiberboard torn from the membrane. The metacarpal head passes through the ruptured joint capsule, and from the side of the flexor tendon, it is subcutaneous to the palmar side of the hand, and the base of the proximal phalanx is moved to the dorsal side of the metacarpal head.