Patterns of injury to carpal ligaments. A spectrum

The concept of a spectrum of progressive ligamentous injury of the wrist, supported by anatomical and biomechanical data, indicates that a pattern of ligamentous injury begins on the radial side of the wrist. The mechanism of carpal injury associated with this ligamentous damage is a three-dimensional or spatial mechanism including extension, ulnar deviation, and intercarpal supination. Perilunar instability (PLI) begins at the scapholunate joint (Stage I PLI) and may be associated with partial interosseous ligament tears, interosseous ligament elongation, or complete disruption. Radiocapitate ligament failure leads to Stage II (PLI) with opening of the space of Poirier. This proceeds to Stage III (PLI) with radiotriquetral ligament failure. Stage IV (PLI) exhibits dorsal radiocarpal ligament disruption.