四种内固定物固定髋臼后柱骨折的生物力学研究及有限元分析

Posterior column fractures of the acetabulum account for 4.42% of the pelvic and acetabular fractures in adults. Currently, procedures using reconstruction plates or lag screws have been advocated for fixation of posterior column fractures around the world. For reconstruction plate fixation, plate needs to be bended temporarily according to the size of acetabulum before procedure is implemented, but this is limited by the too small fixed range. Also, screw penetration into the hip joint is a potentially serious traumatic complication due to the difficult adustment of screw through the round screw hole, and this incidence is even over 4%. In order to avoid the above-mentioned problems, we originally designed the W-shaped acetabular angular plate and the matched guide apparatus. The W-shaped acetabular angular plate is suited to the acetabular posterior column and extends the fixed range, therefore avoiding the temporary bending; with 4 different models, oval screw hole and matched guide apparatus, guaranting the safe fixation of screws. This project intends to produce posterior column fractures of acetabulum on cadevaric acetabular specimens. These acetabular specimens will be fixed with single plating along the posterior column，double plating, W-shaped acetabular angular plating and a lag screw, respectively. The pressure-sensitive films and extensometers are used to assess the mechanical conduction property and stability of the above-mentioned models. We will also apply finite element analysis technique to establish a normal bony pelvis-ligament model. The finite element model of pelvis with acetabular posterior column fracture will be built, on which the 4 above-mentioned models including single plating，double plating, W-shaped acetabular angular plating and a lag screw are added, respectively. The stress and strain distribution and the stability of the each model is then assessed under loads. Taking into consideration the biomichanical studies of cadaveric specimens and finite element analysis, the four fixators are compared in the ability of stabilizing posterior column fracture of acetabulum and restoring its biomechanical properties. This study will provide biomechanical evidence to select the best fixation technique for posterior column fracture of acetabulum.

髋臼后柱骨折占骨盆环和髋臼骨折的4.4%，目前全世界均采用重建接骨板或拉力螺钉固定。重建接骨板固定需根据髋臼大小临时预弯，且固定范围小；接骨板的圆形螺孔不易调整螺钉方向，螺钉误入髋臼的发生率超过4%，易致创伤性关节炎等并发症。针对上述难题，我们原创性的研制了与髋臼后柱解剖适形无需预弯的W型髋臼安全角度接骨板和配套的导向器，分为4种型号，螺孔为椭圆形，配以导向器可安全置入螺钉固定。本课题拟制作髋臼后柱骨折模型，采用单接骨板、双接骨板、W型髋臼安全角度接骨板和拉力螺钉固定，应用引伸计和压敏片考察髋臼标本的稳定性和髋关节的力学传导特性。并将采用有限元分析技术，建立正常骨盆-韧带有限元模型及髋臼后柱骨折应用上述4种内固定物固定的有限元模型，考量其应力应变分布和固定的稳定性。与生物力学试验相互验证，比较4种内固定物固定髋臼后柱骨折的稳定性以及生物力学特性，为髋臼后柱骨折选择最佳固定方式提供相关依据。

在髋臼骨折的各种分型中，累及后壁和后柱的骨折较为多见，常用的内固定装置有重建接骨板、锁定接骨板和拉力螺钉。 由于术中视野有限，对显露部位的解剖形态和髋臼特点要有整体性认识，复位完成后放置在后柱的接骨板需要预弯成髋臼后柱匹配的形态，如果经验不足将会耽误手术时间。而且常用的重建接骨板预弯后可能出现覆盖面积不足、稳定性差等情况，而附加使用拉力螺钉或接骨板虽然稳定性获得提高，但要在术中增加显露范围，出血和神经损伤率相应增高。.针对上述问题，本课题进行了W型安全角度接骨板（W-shaped acetabular angular plate, WAAP）与常用三种内固定方式固定髋臼后柱骨折的生物力学比较；分析了髋臼后柱复位程度与髋臼周围应力分布特点，建立髋臼后柱伴后壁骨折模型，并比较W型安全角度接骨板固定的生物力学特点，最后评估了W型安全角度接骨板治疗髋臼后部骨折的疗效。.生物力学结果证明W型髋臼安全角度接骨板具有符合后柱的解剖形态、支撑与锁定固定相结合、螺钉角度安全等优点，固定坚强，能够使髋臼周围恢复正常的应力分布。发现W型安全角度接骨板和双重建板的固定刚度无显著性差异，均能够恢复髋臼周围的应力分布，而W型板在固定和使用时更具有优势。.临床研究证明W型髋臼安全角度接骨板可单独或联合用于髋臼后部骨折的固定，能够避免螺钉误入关节、减少手术时间和术中出血，术后恢复早期活动。