Finger Dislocation
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Original Editor - Puja Gaikwad
Top Contributors - Puja Gaikwad, Kim Jackson, Anas Mohamed, Shaimaa Eldib, Rucha Gadgil and Wanda van Niekerk
Introduction[edit | edit source]
Clinically Relevant Anatomy[edit | edit source]
Fingers consist of three joints: Metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and the distal interphalangeal (DIP) joints. The MCP joint is located between metacarpals and proximal phalanges. The PIP and DIP joints are hinge joints between proximal and middle phalanges and between the middle and distal phalanges respectively. These PIP and DIP joints allow flexion and extension, which helps in grasping, pinching, and clawing or reaching functions. The middle phalanx range of motion available at the PIP joint is 105+/- 5 degrees and accounts for the fingertip flexion during grasping. Flexion and extension of the digit are also possible at the metacarpophalangeal joint; however, the MCP joint performs flexion, extension, adduction, abduction, and circumduction.
The phalangeal joints have stabilizers that provide support during motion. There are static and dynamic joint stabilizers. Static stabilizers involve non-contractile tissue, collateral ligaments, volar plate, dorsal capsule, sagittal bands, ulnar, and radial collateral ligaments, etc. The volar plate is an important stabilizer as it holds up the volar side of the joint capsule and maintains stability and thereby prevents hyperextension of the finger joints. The collateral ligaments provide stabilization against the radial and ulnar deviation of the IP joints. Sagittal bands encircle the metacarpophalangeal joint to keep the extensor tendon centralized and thereby prevent bowstringing. Dynamic stabilizers include extrinsic and intrinsic muscles and tendons. Two major dynamic stabilizers are central slip and lateral bands. The central slip tendon is placed dorsally and provides a PIP joint extension, and the lateral bands provide a DIP joint extension. Lastly, digital arteries and nerves are found in the volar aspect and appear on both ulnar and radial sides of the digits.
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