Wedge osteotomies of the radius for Kienböck's disease: a biomechanical analysis

We compared changes in lunate cortical strain with an applied physiologic load by altering radial inclination to simulate opening and closing wedge osteotomies of the distal radius. Nineteen fresh-frozen cadaver arms were mounted in neutral position and tested under axial compression at a physiologic load by means of a repeated-measures design. Principal compressive strains were measured with rosette strain gauges mounted on the lunate's palmar and dorsal cortices. Distal radius osteotomy and custom external fixator allowed for altering radial inclination in progressive 3 degrees increments both by increasing and decreasing radial inclination in each specimen. Maximum principal strain was recorded for each inclination increment and compared with control. Comparison of all data showed a 26% decrease on lunate cortical strain for the radial opening wedge osteotomy and a 24% increase for the radial closing wedge osteotomy. This difference was statistically significant. No significant differences were found between individual angular increments (3 degrees to 15 degrees). The radial opening wedge osteotomy was more effective than the radial closing wedge osteotomy at diminishing lunate strain. The results validate the biomechanical effectiveness of this extra-articular osteotomy, which is intended to minimize alteration of ulnar variation.