Ligament stability of the metacarpophalangeal joint: a biomechanical study.

Capsuloligamentous contributions to metacarpophalangeal joint stability were obtained from load-displacement tests on the joints of 15 human cadavers. The contribution of each ligament to joint stability was obtained by measuring the reduction of load that induced a given joint displacement after sequential ligamentous sectioning. Four modes of joint displacement were examined: distal distraction, dorsopalmar dislocation, abduction-adduction rotations, and supination-pronation rotations. This study demonstrated that both radial and ulnar collateral ligaments play primary roles in stabilizing the metacarpophalangeal joint in all four modes of joint displacement. The accessory collateral ligaments contribute primarily to abduction-adduction rotational stability, but contribute little to stabilizing dorsopalmar dislocation or axial (supination-pronation) rotations. The palmar plate prevents dorsal dislocation only at full extension. The dorsal capsule has a moderate contribution to stability in distraction and supination-pronation rotations.