Objective: To summarize the new research progress in distal interlocking screws of cephalomedullary nails for the treatment of intertrochanteric fractures.
Methods: Relevant domestic and foreign literature was extensively reviewed to summarize the static/dynamic types of distal interlocking screw holes, biomechanical studies, clinical studies and application principles, effects on toggling in the cavity, and related complications of distal interlocking screws.
Results: The mode of the distal interlocking screw holes can be divided into static and dynamic. Distal interlocking screws play the role of anti-rotation, maintaining femur length, resisting compression stress, increasing torque stiffness, resisting varus stress, etc. The number of the screws directly affects the toggling of the main nail in the cavity. At present, regardless of whether long or short nails are used, distal interlocking screws are routinely inserted in clinical practice. However, using distal interlocking screws can significantly increase the duration of anesthesia and operation, increase fluoroscopy exposure time, surgical blood loss, and incision length. There is a trend of trying not to use distal interlocking screws in recent years. No significant difference is found in some studies between the effectiveness of dynamic and static interlocking for AO/Orthopaedic Trauma Association (AO/OTA) 31-A1/2 fractures. At present, the selection of the number and mode of distal interlocking screws is still controversial. When inserting distal interlocking screws, orthopedists should endeavor to minimize the occurrence of complications concerning miss shot, vascular injuries, local stress stimulation, and peri-implant fractures.
Conclusion: Distal interlocking screws are mainly used to prevent rotation. For stable fractures with intact lateral walls, long cephalomedullary nails can be used without distal interlocking screws. For any type of intertrochanteric fractures, distal interlocking screws are required when using short cephalomedullary nails for fixation. Different interlocking modes, the number of interlocking screws, and the application prospects of absorbable interlocking screws may be future research directions.
目的: 总结股骨转子间骨折头髓钉治疗中远侧交锁螺钉的研究新进展，为临床提供参考。.
方法: 广泛查阅国内外相关文献，从远侧交锁螺钉孔的类型，远侧交锁螺钉的生物力学、临床应用研究和原则、对头髓钉摆动的影响、相关并发症等方面进行总结。.
结果: 远侧交锁螺钉孔可分为静态孔和动态孔。远侧交锁螺钉具有防旋、维持股骨长度、抵抗压缩应力、增加扭矩刚度、抵抗内翻应力等作用，其数量直接影响主钉在髓腔内的摆动。目前无论选用长钉还是短钉，临床上都常规植入远侧交锁螺钉；但使用远侧交锁螺钉会增加麻醉时间、手术时间、透视时间、手术失血和切口长度，近年来有尝试不使用远侧交锁螺钉的趋势。对于国际内固定研究协会/美国骨创伤协会（AO/OTA）31-A1/2型骨折，动、静态交锁的临床疗效无明显差异。目前关于远侧交锁螺钉数量和模式的选择仍有争议，使用时应尽量减少打不准、血管损伤、局部应力刺激、内植物周围骨折相关并发症的发生。.
结论: 远侧交锁螺钉主要起防止股骨干旋转的作用。对于外侧壁完整的稳定型骨折，采用长钉固定时可不使用远侧交锁螺钉；对于任何类型的股骨转子间骨折，采用短钉固定时需常规打入远侧交锁螺钉。不同交锁模式、交锁螺钉数量和可吸收交锁螺钉的应用将是未来研究方向。.
Keywords: Intertrochanteric fractures; biomechanical study; cephalomedullary nail; clinical study; complication; distal interlocking screw.