The effects of partial carpal fusions on wrist range of motion.

UNLABELLED: The objective of this investigation was to evaluate the effects of different partial wrist fusions on wrist motion. A total of 20 cadaveric wrists were tested in the intact state and after undergoing either a four-corner fusion or 2- and 3-bone fusion. The moment-rotation behaviour was measured in 24 directions of wrist motion about the forearm axis. The 2- and 3-bone fusion groups demonstrated increased radial deviation and pure flexion. Pure flexion was decreased in the four-corner fusion group. Radial extension and pure extension were decreased in all treatments compared with normal range of motion. Increasing the number of carpal bones within the fusion construct did not alter the functional axis of the wrist. Essentially equivalent motion is possible with 2-bone, 3-bone and four-corner fusions, with the exceptions of pure flexion and radial deviation. This data may influence surgeons when choosing between treatment methods. LEVEL OF EVIDENCE: N/A.