关于温哥华C型股骨假体周围骨折采用不同长度锁定钢板固定的生物力学研究

目的通过比较四种不同长度的锁定钢板在治疗温哥华C型股骨假体周围骨折的生物力学实验中的表现,来分析锁定钢板相对于股骨假体柄远端的位置与产生的刚度和应力集中情况的关系。方法选取10对成人新鲜股骨标本,随机均分为四组,制作温哥华C型股骨假体周围骨折模型,以四种不同长度的锁定钢板固定:A组,钢板最近端双皮质锁定螺钉距离假体尖端1个股骨直径;B组,钢板最近端双皮质锁定螺钉与假体尖端平齐;C组,钢板最近端单皮质锁钉与假体尖端重叠1个股骨直径;D组,钢板最近端单皮质锁钉与假体尖端重叠2个股骨直径。分别进行轴向压载实验、扭转实验、内外四点侧弯实验及前后四点侧弯实验,记录各组数据并进行统计学分析;最后进行循环负载实验,记录骨折情况。结果各组在各实验中表现出的刚度值有显著差异,D组刚度值最大(P<0.05);在循环负载实验中,D组骨折线分布于股骨假体尖端、近端锁钉以及钢板远端附近,A、C组的骨折线集中在近端锁钉与股骨假体尖端之间,B组骨折线集中在股骨假体尖端与钢板顶端的线性区域内,结果显示D组应力集中程度比A、B、C三组低(P<0.05)。结论在使用锁定钢板治疗温哥华C型股骨假体周围骨折时,随着钢板长度增加,内固定稳定性提高;锁定钢板与股骨假体柄尖端重叠固定不会增加应力集中,反而随着钢板与股骨假体重叠区域增加,应力显著分散。

Biomechanical comparison of Vancouver C type periprosthetic femoral fractures Fixed with Locking Plate Of Different Length

ObjectiveComparing the biomechanical differences of four different locking plate fixation of different lengths in the treatment of Vancouver C type periprosthetic femoral fractures, the relationship between the position of locking plates relative to the distal end of the femoral stem and the stiffness and stress concentration was analyzed. MethodsTen pairs of fresh adult femoral specimens were randomly divided into four groups. Then, the modle of Vancouver C type periprosthetic femoral fractures was established. Fixed with locking plates of four different lengths: in group A, the proximal bicortical locking screw of the plate was 1 femoral diameter to the tip of the prosthesis; in group B, the proximal bicortical locking screw of the plate was the same level with the tip of the prosthesis; in group C, the proximal single cortical locking screw of the plate overlapped with the tip of the prosthesis by 1 femoral diameter; in group D, the proximal single cortical locking screw of the plate overlapped with the tip of the prosthesis by 2 femoral diameter. All of the models are performed by axial ballast test, torsion test, four-point bend test inside and outside, and four-point bend test front and behind. The data of each group were recorded and analyzed statisticallyby SPSS software. Finally, the cyclic loading test was carried out and the fracture line distribution was recorded. ResultsThe stiffness of each group showed significant difference, and the stiffness of group D were the largest in all tests (P<0.05). In the cyclic loading experiment, the fracture of group D were distributed near the tips of femoral prosthesis, proximal locking nails and distal plates. The fracture of group A and C were concentrated between proximal locking nails and the tips of femoral prosthesis. The fracture of group B were concentrated in the linear region between the tips of femoral prosthesis and the tips of steel plates. The results showed that the stress concentration of group D was lower than that of group A, B and C (P<0.05). ConclusionsIn the treatment of Vancouver Ctype periprosthetic femoral fractures with locking plate, the stability of internal fixation increases with the plate length; the overlapping fixation of locking plate and the tip of femoral stem does not increase the stress concentration, and the stress is significantly dispersed, with increasing with the overlapping area of plate and femoral prosthesis.