Clinical and biomechanical investigation of an increased articular cavity depth after distal radius fractures: effect on range of motion, osteoarthrosis and loading patterns

After fracture, distal radius malunion with dissociation of the volar and dorsal ulnar fracture fragments can lead to an increased articular cavity. To investigate its clinical impact we retrospectively analyzed the outcome of 81 patients and simulated this form of malunion in a biomechanical experiment with six cadaver specimens in a dynamic loading set-up. In clinics, a higher arthritis stage was significantly correlated with an increased articular cavity depth and an increased anterioposterior distance. In cadaver specimens, a significantly decreased range of motion and significantly altered intraarticular contact characteristics were recognized for an increased cavity. Alterations in contact biomechanics could be one reason for the higher incidence of posttraumatic osteoarthritis when a deeper central impaction of the distal radius is present. From a clinical and experimental point of view, restoration of the normal shape of the distal radius is considered to minimize the risk for posttraumatic radiocarpal osteoarthritis.