Dislocation of a digit is common among skeletally mature adolescents and active young adults. Dorsal displacement of the proximal interphalangeal joint of the finger is the most frequent dislocation . On the other hand, double dislocations of the finger interphalangeal and/or metacarpophalangeal joints are a rare entity . The primary management of digital joint dislocations consists of radiographic exclusion of a fracture, joint reduction after appropriate analgesia and/or regional anesthesia, and splinting.
The reduction of digit dislocations is reviewed here. The treatment of toe and finger fractures is discussed separately. (See "Metatarsal and toe fractures in children" and "Toe fractures in adults" and "Proximal phalanx fractures" and "Middle phalanx fractures" and "Distal phalanx fractures".)
Finger function involves a complex interaction among multiple joints, flexor and extensor tendons, and supporting fascia and ligaments. Each of the digits, except the thumb, has three phalanges with three hinged joints: distal interphalangeal (DIP), proximal interphalangeal (PIP), and metacarpophalangeal (MCP) (figure 1). Joint stability is provided by the structure of the phalanges, joint capsule, radial and ulnar collateral ligaments, and dorsal and palmar ligaments. (See "Finger and thumb anatomy".)
Flexion and extension are the primary movements of the fingers. Abduction and adduction can be performed at the MCP joints. The thumb is capable of opposition, abduction, adduction, and retropulsion, in addition to flexion and extension.
At the metacarpophalangeal (MCP) joints, lateral motion is limited by the collateral ligaments, which are actually lateral oblique in position rather than true lateral. Triangular in shape, these ligaments arise from the lateral head of each metacarpal bone and attach to the base of the proximal phalanx distally. Because of these anatomical features, the MCP joint is more stable in flexion than in extension due to stabilization by the collateral ligaments (figure 2) . The volar plate is part of the joint capsule that attaches only to the proximal phalanx, allowing hyperextension. The volar plate is the site of insertion for the intermetacarpal ligaments. The intermetacarpal ligaments restrict the separation of the metacarpal heads.