Finger Dislocation

Excerpt

Finger joint dislocation is a common hand injury. Finger dislocation can occur at the proximal interphalangeal (PIP), distal interphalangeal (DIP), or metacarpophalangeal (MCP) joints. This paper discusses the epidemiology, anatomy, examination, imaging, treatment, and complications of finger dislocation.

Fingers have three joints: the metacarpophalangeal (MCP) joint, the proximal interphalangeal (PIP) joint, and the distal interphalangeal (DIP) joint. The MCP joint is between the metacarpals and proximal phalanges. The PIP joint is a hinge joint between the proximal and middle phalanges. The DIP is also a hinge joint and is between the middle and distal phalanges. The range of motion of these joints allows for flexion and extension, which provides grasping, pinching, and clawing or reaching functions of the fingers. The middle phalanx range of motion at the PIP joint is 105 +/- 5 degrees and accounts for the majority of the flexion of the fingertip during grasping. Flexion and extension of the digit are also possible at the metacarpophalangeal joint; however, the MCP joint can also perform adduction, abduction, and circumduction.

The phalangeal joints have important stabilizers that provide necessary support during motion. Joint stabilizers are both static and dynamic. Static stabilizers consist of non-contractile tissue, including the collateral ligaments, volar plate, dorsal capsule, sagittal bands, and ulnar and radial collateral ligaments. The volar plate is an essential stabilizer as it reinforces the volar side of the joint capsule and maintains stability by preventing hyperextension of the finger joints. The collateral ligaments provide stabilization against radial and ulnar deviation of the interphalangeal joints. Sagittal bands encircle the MCP joint to keep the extensor tendon centralized and to prevent bowstringing. Dynamic stabilizers include extrinsic and intrinsic tendons and muscles, and two important dynamic stabilizers are the central slip and lateral bands. The central slip tendon is found dorsally and provides for PIP joint extension, and the lateral bands provide DIP joint extension. Finally, digital arteries and nerves are found volar and appear on both the ulnar and radial sides of the digit.