The complex motion of the wrist depends on the interactions between carpal bones and the ligaments attached to them. Injury to ligament structures will result in wrist instability and loss of function, based on severity of injury. One of the most common instabilities of the wrist is scapholunate dissociation which is caused by injury (wrist in hyperextension or supination) to the scapholunate ligament. If untreated, scapholunate joint instability will progress and finally lead to osteoarthritis (OA), a serious and debilitating condition. Surgical intervention may alleviate pain, may restore both carpal alignment and contact mechanics to normal values and may prevent progression of OA. The effects of injury and surgical repair on midcarpal joint mechanics were studied in vivo, noninvasively, with use of magnetic resonance imaging (MRI) and the efficient computational methods of surface contact modeling (SCM). Carpal geometries (bones and cartilage) were constructed from MR images of the wrist in a relaxed (unloaded) state for the normal, injured (scapholunate ligament injury) and postoperative wrist. Kinematic transformations were obtained through registration between the relaxed (unloaded) and active grasp (loaded) image sets. Contact mechanics (contact force, peak contact pressure, contact area and mean contact area) were calculated for each wrist condition (normal, injured and postoperative). Results showed a trend of an increase with scapholunate ligament injury for all contact measures for both scaphocapitate and lunocapitate articulations. A significant increase was observed in contact area between the normal and injured wrists in the scaphocapitate joint. Also, a significant increase was observed in peak contact pressure between the normal and postoperative wrists in the scaphocapitate articulation. This work demonstrated the ability to measure mid-carpal mechanics in vivo.