Carpal Biomechanics: Application to Ligamentous Injuries

Since Destot in 1905, the study of intracarpal injuries has interested many authors who were faced with wrist traumatisms [ 1– 7 ] . Therefore, the analysis of the sole traumas is not enough to understand carpal biomechanics. Studies have thus been led in different directions to solve injuries’ mechanism. Imaging studies dealt with the radiography of healthy subjects [ 8– 17 ] , with the in vitro measure of intracarpal movements [ 18– 27 ] and then in vivo by CT scan [ 28– 40 ] . The radiographic studies of healthy subjects enabled to measure the shift of the bones that could be seen on front and pro fi le views. But the bone superposition and the out-of-theradiographic-plane position of some bones do not allow to measure all the displacements. Cadaveric studies allowed researchers to fi x markers on carpal bones to differentiate them better and measure their movements. The authors of these studies mostly resorted to metallic markers, which shifting was recorded by stereoradiography. Yet, the necessary surgical approach to introduce the markers and their presence inside the wrist involve a doubt on the similarity in between in vivo results [ 23, 28, 29 ] . Recent CT scan studies measured in vivo the in-plane and out-of-plane movements of the bones [ 28, 29, 36, 38– 40 ] . These studies enabled to draw an accurate view of carpal biomechanics. In vitro studies on carpal ligament sections were useful to start some ligamentous traumatic sequences. Several carpal restraints are thus described [ 7, 41– 50 ] . Works on forces transmission enabled to explain the different strains applied to the moving wrist [ 51– 58 ] . As the study and the diagnosis of carpal ligamentous injuries are dif fi cult, it seems necessary to present a biomechanical synthesis of the available data on the topic.