Objective To find out some parameters to judge the stability of the wrists after four-corner arthrodesis and to explore the strategyfor improving the range of motion (ROM) of the wrist after four-corner arthrodesis. Methods After the simulated four-corner arthrodesis was performed in both wrists of 8 men and 4 women cadaver, the wrists were fixed on the wrist motor simulator; and wrist movement including flexion, extension, radial deviation, ulnar deviation was simulated. The standard posteroanterior and lateral radiographs were taken for measuring the change of capitolunate angle（α）, radiolunate angle（β）, capitolunate posteroanterior angle（θ）, the height（H）and width（W）of the fused four carpal bone bloc. Results There were statistically significant differences in α,β,θ angles (P＜0.01) in the case of 50° flexion or 40° extension, and in H and W values (P＜0.05) in the case of 25° ulnar deviation or 15° radial deviation when compared with before movement. Conclusion Capitolunate angle, radiolunate angle, capitolunate posteroanterior angle, the height and the width of thefused four carpal bone bloc can be used to judge the stability of the wrists after four-corner arthrodesis.
