EXPERIMENTALLY-INDUCED ULNO-CARPAL INSTABILITY - A STUDY ON 13 CADAVER WRISTS

This experimental work studies the role of ligamentous structures in s uspending the carpal bones from the radius and ulna. Thirteen human ca daver wrists underwent a distal radio-ulnar arthrodesis in a neutral p osition and an arthrodesis between the three bones of the first carpal row. Progressive postero-anterior forces in a palmar direction were a pplied to the fused carpal bones, Displacement was measured by two dia l gauges before and after sequential section of the different fibrous structures. The largest absolute average displacement (both, dorso-pal mar and induced rotational displacement) was observed after section of the ulnar styloid process. No significant differences were observed a fter section of the extensor retinaculum, extensor carpi ulnaris sheat h, posterior ulno-carpal and posterior radio-carpal ligaments. This wo rk suggests that the carpus is suspended not only from the radius, but also from the distal ulna and particularly at the ulnar styloid and t he structures which insert onto it.