[Biomechanics of the carpus--functional anatomy and movement analysis of the carpal bones].

The often unsatisfactory outcome of attempts to reconstruct ligaments and perform partial arthrodeses of the wrist bones has prompted us to investigate the kinematic behavior of the proximal row of carpal bones in their immediate environment. The movements of the individual bones were observed on fresh autopsy specimens before they were dissected to study the exact location of the interconnecting ligaments. Finally, a special model of epoxy resin was made in which the exact form of the joint surfaces (cartilage surfaces) was maintained. The ligaments were simulated by means of stout threads and, according to the observations recorded in the previous study, attached to the model bones. In this manner a working model resulted that not only proved the correct positioning of the ligaments, but also enabled their function in controlling the movements of the bones during dorsal-palmar flexion and radial-ulnar abduction of the wrist to be established. It was seen that movement of the proximal row of carpal bones is caused primarily by the orientation of the adjoining articular surfaces and limited by the ligaments. Therefore, it is of paramount importance that the friction at the joint surfaces remains as low as possible. If the friction increases, the "floating" bones can no longer slide under load and movement of the hand becomes limited.