桡骨掌倾角改变对桡腕关节稳定性影响的生物力学研究

Palmar tilt changes due to distal radius fractures and radiocarpal instability:a biomechanical study

目的研究桡骨远端骨折背侧成角畸形对桡腕关节稳定性的影响。方法制作桡骨远端FrykmanⅠ型不稳定骨折模型,应用压力敏感片测不同掌倾角改变时桡腕关节面上桡舟、桡月接触面积及压力变化情况,并摄腕关节侧位X线片。结果桡腕关节面背倾角度超过10°时,桡舟、桡月接触面积显著减少并向背侧移位,桡舟接触面压力显著增加;X线侧位片显示当背侧成角大于40°时可出现腕骨背侧半脱位。结论桡骨远端骨折背侧成角畸形背倾角度大于10°是其发生腕不稳定的最初原因。

Objective To investigate the impact of dorsally angulated malunited distal radius fractures on the stability of the radiocarpal joint. Methods Eight fresh upper limb specimens from 4 human cadavers were obtained, in which radial osteotomy was performed to prepare models of FrykmanⅠdistal radius fracture. Pressure-sensitive film was applied to study the changes in the contact area distribution and the pressure load across the radiocarpal joint in response to palmar tilt variation, and the lateral radiograph of the wrist was taken at the end of pressure loading. Results When the dorsal tilt exceeded 10°, the radioscaphoid and radiolunate articular contact areas were markedly decreased (P<0.01) and shifted to the dorsal aspect of the radiocarpal joint, where the pressure load was significantly increased (P<0.01). A dorsal radiocarpal subluxation was liable to occur on the sagittal plane when the dorsal tilt exceeded 40°. Conclusion A dorsal tilt over 10°is the most primary cause of radiocarpal instability after a dorsal deformity due to distal radius fractures.