Biomechanical effect of isolated capitate shortening in Kienbock's disease: an anatomical study

Multiple operations have been proposed to slow the progression of osteonecrosis and secondary carpal damage in Kienböck's disease. To assess the biomechanical changes after capitate shorting, we inserted pressure-testing devices into the carpal and radiocarpal joints in an anatomical study. Pressure sensors were placed into eight thawed non-fixated human cadaver arms to measure the forces transmitted in physiological loading. Longitudinal 9.8 N and 19.6 N forces were applied before and after capitate shortening. After capitate shortening, significant load reduction on the lunate was evident in all specimens. An average decrease of 49% was seen under a 9.8 N load and 56% under a 19.6 N load. The load was transferred to the radial and ulnar intercarpal joints. More relief of pressure on the lunate after isolated capitate shortening is achieved with a shallow angle between the scaphoid and capitate in the posteroanterior radiograph.