Objective To compare the stability between K-wires and scaphoid-trapezium-trapezoid (STT) fusion apparatus when they were used as internal fixation devices in scaphoid-trapezium-trapezoid arthrodesis. Methods Scaphoid-trapezium-trapezoid arthrodesis was simulated in 12 fresh cadaver wrists. The specimens were randomly divided into two groups. In the K-wire group, K-wires were used for the fusion. In the STT fusion apparatus group, STT arthrodesis was done with the fusion device. The specimens were then attached by a clamping mechanism to the wrist motion simulator. Postern-anterior and lateral wrist radiographs were obtained before and after simulated wrist movements, and the radioscaphoid angle (RSA), radioscaphoid space,scaphoid length, and stable angle of STT fusion body were measured and compared. Results STT fusion apparatus group: There were no significant changes in the tested parameters after the wrists moved to 45° flexion,40° extension, 30° ulnar deviation and 15° radial deviation(P ＞ 0.05). K-wire group: The test parameters significantly changed from bseline values when wrists moved to 35° flexion, 30° extension, and 10° radial deviation ( P ＜0.05). In addition, the stable angle of STT fusion body showed statistically significant difference when ulnar deviation reached 30°. Conclusion The STT fusion apparatus is more stable than K-wires when it is used in scaphoid-trapezium-trapezoid arthrodesis.%目的 比较舟骨和大、小多角骨(scaphoid-trapezium-trapezoid,STT)融合器与克氏针在STT融合术中内固定强度的差异.方法 12侧新鲜冷冻尸体前臂标本,随机分为融合器组(使用STT融合器)和克氏针组(使用克氏针)2组,模拟进行STT融合术,术后以夹具固定于腕动力测试仪上模拟腕关节主要活动.活动前后均拍摄腕关节标准正侧位X线片,测量桡舟角、桡舟间距、舟骨长度及STT融合体稳定角.结果 融合器组:当腕关节运动范围增加到屈曲45°、背伸40°、尺偏30°、桡偏15°时,客观指标与初始状态相比较变化差异均无统计学意义(P＞0.05).克氏针组:当腕关节运动范围增加到屈曲35°、背伸30°、桡偏10°时,客观指标与初始状态相比较变化差异均有统计学意义(P＜0.05).尺偏30°运动后融合体稳定角与初始状态相比较差异有统计学意义(P＜0.05).结论 STT融合器在舟骨和大、小多角骨融合术中内固定强度大于传统内固定物中的克氏针.
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