A method to study ligament-length patterns in situ with roentgenstereophotogrammetry,
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.