内锁钉断裂的生物力学原因分析

从1992年3月至1997年12月,对64例复杂粉碎性股骨骨折作了内锁钉固定。55例得到随访,从3个月到90个月(平均26个月)。共发生4例内锁钉断裂,断钉率为6.3％。经梅花钉固定加植骨3例,记忆合金环抱接骨器固定加植骨1例,骨折均愈合,并且功能3例优良,1例差。断钉发生在术后6月至14月,3例位于骨折远端第一枚横锁螺孔处,1例位于内锁钉中段。断钉原因有:开放穿钉,过度分离骨膜,过早负重及功能锻炼不合适等。另外,股骨远端第一枚横锁螺钉离骨折端太近,此处应力过于集中。预防断裂的方法有尽量闭合穿钉,选择较粗较长的内锁钉,横穿内锁螺钉应稍远离骨折端、避免过早负重及合适的功能锻炼等。

Biomechanical analysis of the failure of the interlocking nails

From March 1992 to December 1997,64 patients with complex femur fractures were treated wiih the interlocking nails at our hospital. 55 cases were followed-up for at least 3 months , from 3 months to 90 months, avergage 26 months. There were 4 breakages in the locking nails. The percentage of failure is 6. 3%-After reinterfixzation with the Kuntscher nails(3 cases) or remmber-aloy-osteosythesis instrument,in the meantime planted with the bone,the fractures were union. The function was excelent in 3 cases ,poor in one case. The failure occured 6 to 14 months after operation. 3 cases were at the first screw site of the distal part of the fracture, 1 case at the middle of he nail. The reasons of breakage concludes open operation .separate the periosteum too much,too early full weight bearing and unfitable function exercise. Besides,the distal first screw was to near the farcture site,where the stress was most concentrated. The prevention of failure involves closed interlocing,using the more longer and thicker nail,the distal first screw is a little more distal to fracture site .avoiding early full weight beraring and the fitted function exer-