Quantification of anatomic, geometric, and load transfer characteristics of the wrist joint.

The work reported here is an assimilation of 8 years of research, the purpose of which was to gain a better understanding of the normal and abnormal workings of the wrist joint. The results are summarized in three major areas of concentration: descriptive anatomic studies, which include direct measurements of cadaver specimens, biomechanical loading studies to define load distribution through normal and abnormal wrists, and three-dimensional (3D) anatomy studies using solid models derived from computed tomographic (CT) images of in vivo and cadaver wrists. The descriptive anatomic studies used 393 cadaver wrists to evaluate the incidence and distribution of anatomic features, arthroses, chondromalacia, and soft-tissue lesions. The data were analyzed for any statistically significant associations among different variables. The biomechanical studies characterized the biomechanics of the human wrist in a variety of normal, simulated traumatic, and surgically treated conditions. The results of the load studies have provided clinically relevant information on the normal anatomy and functional mechanics of the wrist as well as guidelines for the treatment of a number of different fractures and ligament injuries. The 3D anatomic studies use quantitative analysis of 3D reconstructions of CT scan data to build a normative database of carpal bone morphology. Thirty-five wrists were imaged in a CT scanner. Quantitative measurements of volume, surface area, maximum length, and intercarpal distances were than assessed. A reliable 3D carpal height ratio (3DCHR) was calculated by dividing the capitate maximum length by the carpal height, which is the minimum distance between the fourth metacarpal and the radius.