BIOMECHANICAL ANALYSIS OF CAPITATE SHORTENING WITH CAPITATE HAMATE FUSION IN THE TREATMENT OF KIENBOCKS-DISEASE

The biomechanical effects of surgical treatment options for Kienbock's disease have been compared. However, no study has included a direct a nalysis of capitate shortening along with capitate-hamate fusion (CSCH F). To investigate the biomechanical effects of CSCHF, a cadaver model of the upper extremity was used to determine radiocarpal articular pr essure changes resulting from this procedure using pressure-sensitive film. Ten specimens were tested by placing each in an apparatus that a pplied load across the radiocarpal joint through the wrist flexor and extensor tendons. Testing was performed in 3 wrist positions (ulnar de viation, radial deviation, and neutral) combined with 3 forearm positi ons (pronation, supination, and neutral) and neutral flexion/extension . Radioscaphoid, radiolunate, and mean contact pressures in the entire radiocarpal joint were determined for each of the 9 wrist positions, both intact and after surgery. The radioscaphoid mean pressure increas ed in 6 of 9 positions and was unchanged in 3 positions. The radioluna te mean pressure decreased in 9 of 9 positions. The radiocarpal mean p ressure increased in 2 of 9 positions and was unchanged in 7 positions . These data suggests that CSCHF increases radioscaphoid mean pressure , decreases radiolunate mean pressure, and has little effect on radioc arpal mean pressure. Copyright (C) 1998 by the American Society for Su rgery of the Hand.