Three-dimensional motion patterns of the carpal bones: an in vivo study using three-dimensional computed tomography and clinical applications.

A three-dimensional (3D) CT technique was developed to analyze in vivo segmental carpal kinematics. Transverse CT data of the distal forearm, carpals and proximal metacarpals was acquired and 3D reconstructed in various wrist positions. Carpal kinematics were analyzed in two groups of 20 asymptomatic volunteers, one group in neutral position, flexion and extension (45 degrees), and the other group in neutral position, radial (15 degrees) and ulnar deviation (30 degrees). Qualitative analysis included the 3D study of carpal anatomy, and comparison of carpal bone position between the different sets of data obtained. Carpal bone motion was quantified using rigid body and finite helical axis concepts. The results, although agreeing in principle with previous findings, showed important individual variations in carpal bone motion. Clinical applications were conducted in a series of 25 patients with various wrist disorders. There was no significant difference between the injured wrist and the heterolateral, asymptomatic wrist, but there was a significant difference between asymptomatic volunteers and both the injured wrist and heterolateral wrist of patients. In particular, scaphoid motion was altered bilaterally in our patient group, suggesting the existence of anatomic and/or kinematic factors predisposing to certain carpal pathologies. This hypothesis needs to be confirmed and refined.