Wrist-joint ligament length changes in flexion and deviation of the hand: an experimental study.

A method to study ligament-length patterns in situ with roentgen-stereophotogrammetry, using strings of glued tantalum markers, was developed. The method was tested against a bone-to-bone marking method in five carpal ligaments in three specimens, whereby the hand was moved through dorsopalmar flexion and radioulnar deviation. The "glued-string" marking method was found to be superior to the bone-to-bone marking method. The length patterns obtained were found to be reproducible in the specimens and different from earlier expectations presented in the literature. The radiocapitate ligament seems to limit the displacements of the capitate in both radial and ulnar deviation, and dorsal flexion. The radiolunate ligament has the same effect for the lunate. Both the dorsal radiotriquetrum and the palmar triquetrocapitate ligaments seem to play a stabilizing role in the neutral position of the hand, whereas the radiotriquetrum ligament also has a function in palmar flexion and the triquetrocapitate ligament functions in dorsal flexion, ultimately resisting these excursions. These findings require confirmation in more extensive experiments, whereby the relationship between ligament length patterns and carpal motion axes is investigated.