Four-Corner Arthrodesis: Influence of the Position of the Lunate on Postoperative Wrist Motion: A Cadaveric Study

PurposeEvaluate the influence of the position of the lunate on postoperative wrist motion in four-corner arthrodesis.MethodsSix upper cadaveric limbs were evaluated, comparing the total arc of motion in each wrist after simulating four-corner arthrodesis. The lunate was fixed in 3 different positions: neutral (0°), extended (30°), and flexed (20°). Statistical analyses (ANOVA and Bonferroni tests) were carried out to establish the significance of differences in articular motion in these 3 positions.ResultsSignificant statistical differences were observed in full wrist extension. No significant differences, however, were found in flexion-extension total arc of motion, radial deviation, or ulnar deviation.ConclusionsAccording to our results in this cadaveric model, the position of the lunate affects postoperative wrist flexion and extension after four-corner arthrodesis. The flexed lunate position increases postoperative wrist extension and restrains wrist flexion. Inversely, the extended lunate position improves articular flexion and limits extension. Total arc of motion of the fused wrist does not vary in the 3 lunate positions.