不同内固定方式治疗髋臼顶压缩骨折后髋臼负重区接触特性的研究

Contact characteristics research of acetabular weight-bearing area with different internal fixation methods after compression fracture of acetabular dome

目的建立髋臼顶压缩骨折模型,采用压敏片技术测量并探讨3种不同内固定方式固定后髋臼负重区接触特性。方法将16具新鲜成人半骨盆标本随机均分为4组,每组4具。D组为完整髋臼对照组;其余3组制备髋臼顶压缩骨折模型后,A组采用重建接骨板固定方法、B组采用顺行排钉螺钉固定方法、C组采用逆行排钉螺钉固定方法固定骨折。将压敏片贴于股骨头上,于倒置的单足站立位行轴向加载压缩试验,分别测量各组髋臼负重区的负重区面积、平均应力及峰值应力。结果载荷为500 N时,D组髋臼负重区面积显著高于其余各组,平均应力和峰值应力显著低于其余各组,差异均有统计学意义(P<0.05)。B、C组髋臼负重区面积显著高于A组,平均应力及峰值应力显著低于A组,差异均有统计学意义(P<0.05);B、C组间比较上述指标差异均无统计学意义(P>0.05)。结论对于髋臼顶压缩骨折,即使行解剖复位并坚强内固定,髋臼负重区接触特性也不能恢复至正常水平;顺行及逆行排钉螺钉固定与重建接骨板固定相比,能够增加髋臼负重区面积,降低平均应力及峰值应力,可降低创伤性关节炎的发生率。

Objective To establish the model of compression fracture of acetabular dome, and to measure the contact characteristics of acetabular weight-bearing area of acetabulum after 3 kinds of internal fixation. Methods Sixteen fresh adult half pelvis specimens were randomly divided into 4 groups, 4 specimens each group. Group D was the complete acetabulum （control group）, and the remaining 3 groups were prepared acetabular dome compression fracture model. The fractures were fixed with reconstruction plate in group A, antegrade raft screws in group B, and retrograde raft screws in group C. The pressure sensitive films were attached to the femoral head, and the axial compression test was carried out on the inverted single leg standing position. The weight-bearing area, average stress, and peak stress were measured in each group. Results Under the loading of 500 N, the acetabular weight-bearing area was significantly higher in group D than in other 3 groups （P〈0.05）, and the average stress and peak stress were significantly lower than in other 3 groups （P〈0.05）. The acetabular weight-bearing area were significantly higher in group B and group C than in group A, and the average stress and peak stress were significantly lower than in group A （P〈0.05）. There was no significant difference in the above indexes between group B and group C （P〉0.05）. Conclusion For the compression fracture of the acetabular dome, the contact characteristics of the weight-bearing area can not restore to the normal level, even if the anatomical reduction and rigid internal fixation were performed; compared with the reconstruction plate fixation, antegrade and retrograde raft screws fixations can increase the weight-bearing area, reduce the average stress and peak stress, and reduce the incidence of traumatic arthritis.