三种空心钉固定方法治疗PauwelsⅢ型股骨颈骨折的生物力学研究

Biomechanical study of three cannulated screw fixation strategies in the treatment of Pauwels typeⅢfemoral neck fractures

目的比较三种空心钉固定方法治疗PauwelsⅢ型股骨颈骨折的生物力学性能。方法购买18个人工股骨模型,按照Pauwels角70°进行股骨颈截骨,制作PauwelsⅢ型股骨颈骨折模型。随机分成A、B、C三组,每组6个。A组菱形分布螺钉固定、B组3枚空心钉结合内侧支撑钢板固定、C组阿尔法分布螺钉固定。每组选取6个标本置于力学试验机上模拟髋关节受力情况。进行轴向静力学试验、扭转静力学试验。比较分析三组固定方法的轴向刚度、扭转刚度、失效载荷。结果A组轴向刚度(62.28±34.75)N/mm、扭转刚度(2.08±0.60)Nm/°、失效载荷(691.3±257.4)N;B组轴向刚度(68.43±20.28)N/mm、扭转刚度(1.83±0.33)Nm/°、失效载荷(976.5±123.8)N;C组轴向刚度(118.78±53.40)N/mm、扭转刚度(1.21±0.23)Nm/°、失效载荷(989.5±263.0)N。三组轴向刚度、扭转刚度比较差异有统计学意义(P<0.05),两两比较B组及C组失效载荷优于A组,组间比较差异有统计学意义(P<0.05),B组与C组组间比较差异无统计学意义(P>0.05)。结论菱形分布螺钉固定具有更好的抗扭转能力,阿尔法分布螺钉固定抗剪切能力最强,空心钉结合内侧支撑钢板具有适中的抗扭及抗剪切能力。

Objective To investigate the biomechanical properties of three different cannulated screws fixation methods in the treatment of Pauwels type III femoral neck fracture.Methods A total of 18 artificial femuRmodels were purchased,femoral neck osteotomy was performed according to Pauwels Angle 70°,and the Pauwels type III femoral neck fracture model was made.The models were randomly divided into groups A,B and C,with 6 model in each group.Group A was fixed with screws in rhombic distribution,group B with 3 cannulated screws combined with a medial buttress plate,and group C with screws in"alpha"like distribution.Both torsional statics test and axial statics test were performed.The axial stiffness,torsional stiffness and failure load were compared and analyzed among the three groups.Results The axial stiffness,torsional stiffness and failure load were(62.28±34.75)N/mm,(2.08±0.6)Nm/°and(691.33±257.37)N in group A,(68.43±20.28)N/mm,(1.83±0.33)Nm/°and(976.5±123.82)N in group B,and(118.78±53.4)N/mm,(1.21±0.23)Nm/°and(989.5±263.03)N in group C,respectively.The axial and torsional stiffness of the three groups showed statistically significant differences(P<0.05).The failure load in group B and group C was superioRto that in group A(P<0.05),but no statistically significant difference was found between group B and group C(P=0.921).Conclusion Screws in rhombic distribution have betteRtorsion resistance.Fixation with screws in"alpha"like distribution presents the strongest sheaRresistance,and medial buttress plate has moderate torsion and sheaRresistance.