Decompression effect of partial capitate shortening for Kienbock's disease: a biomechanical study

Although capitate shortening for Kienbock's disease decompresses the radiolunate joint, the distal carpal row migrates proximally postoperatively and the carpal alignment subsequently collapses. We hypothesised that partial capitate shortening, in which only the lunate facet of the capitate is shortened and the scaphocapitate joint is preserved, could achieve adequate decompression without carpal collapse. Using 11 cadavers, we measured the intra-articular pressure with an axial load on the radioscaphoid, radiolunate and ulnocarpal joints before and after resection. We also investigated whether the decompression effect is related to the presence of the lunohamate articulation. After resection, the radioscaphoid joint mean pressure was significantly increased by an average of 39%, the radiolunate joint mean pressure was significantly decreased by an average of 53% and the ulnocarpal joint mean pressure was unchanged. The radiolunate joint mean pressure significantly decreased irrespective of the lunohamate articulation status.