外展嵌插型股骨颈骨折对屈髋活动度影响的三维模拟研究

Influences of structural changes after valgus impacted femoral neck fracture on hip range of motion:a 3D simulation test

目的探讨外展嵌插型股骨颈骨折对屈髋活动度的影响,为明确此类骨折内固定手术时是否需行骨折复位提供理论依据。方法①对2019年1~4月上海交通大学附属第六人民医院收治的73例外展嵌插型股骨颈骨折患者的髋关节CT影像进行三维重建,比较患侧和健侧股骨颈干角、股骨前倾角、股骨偏心距、轴向Alpha角、外侧中心边缘角(LCEA)、前侧中心边缘角(ACEA),并测量股骨头中心位移距离,明确骨折对上述指标的影响。②模拟双侧髋关节屈髋运动,比较患侧和健侧屈髋活动度和屈髋90°时内旋活动度(MIR-90°),并采用回归分析明确骨折移位对髋关节活动度的影响。③观察模拟屈髋活动时股骨髋臼接触点在股骨侧的分布,明确骨折移位诱发股髋撞击综合征的潜在好发部位。结果①外展嵌插型股骨颈骨折对股骨颈干角、前倾角、偏心距、轴向Alpha角均有显著影响,患侧颈干角较健侧平均增加5.1°,前倾角减少6.5°,偏心距减少8.2 mm,轴向Alpha角增加9.7°,差异均有统计学意义(P<0.05)。股骨头中心位移距离平均为9.2 mm。患侧LCEA和ACEA与健侧比较差异均无统计学意义(P>0.05)。②骨折后屈髋模拟活动度较健侧平均降低27.0°,MIR-90°较健侧平均降低20.3°,差异均有统计学意义(P<0.05)。回归分析显示股骨前倾角、ACEA和股骨头中心位移距离对髋部活动有显著影响,其中前倾角变化影响最大,若前倾角减少超过7.1°提示屈髋活动度会降低至少20%以上。③骨折侧股骨髋臼撞击点分布更为广泛,其中屈髋撞击点较健侧向外上方延伸,屈髋90°内旋撞击点向内侧延伸。结论股骨颈外展嵌插型骨折前倾角减少7.1°以上会显著影响屈髋活动度且股髋撞击点分布范围扩散,建议内固定治疗时先行骨折复位。

Objective To determine the influences of structural changes after valgus impacted femoral neck fracture on hip range of motion(ROM)so as to provide evidence for clinical judgment of whether reduction is necessary or not in the internal fixation of such fractures.Methods 1.3D reconstructions of the CT hip scans were performed for the 73 patients who had been treated at Department of Orthopaedic Surgery,Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University for valgus impacted femoral neck fractures from January 2019 to April 2019.The femoral neck-shaft angle,anteversion angle,femoral offset,axial alpha angle,lateral center edge angle(LCEA),anterior center edge angle(ACEA)and center displacement were measured and compared between the affected and healthy sides to determine the influences of the fracture on the above indexes.2.Hip motions(flexion and MIR-90°)were simulated on bilateral sides to determine the influences of structural changes after fracture on hip ROM using stepwise regression and Logistic regression.3.The distribution of femoral-acetabular contact points on the femoral side was observed in simulation of hip flexion to detect the potential area for femoracetabular impingement(FAI)induced by the fracture displacement.Results 1.The valgus impacted femoral neck fractures had significant influences on femoral neck-shaft angle,anteversion angle,femoral offset and axial alpha angle.Compared with the healthy side,on average,the femoral neck-shaft angle increased by 5.1°,anteversion angle decreased by 6.5°,femoral offset decreased by 8.2 mm and axial alpha angle increased by 9.7°on the affected side,showing significant differences(P<0.05).The displacements of the femoral head center averaged 9.2 mm.There was no significant difference in LCEA or ACEA between the affected and healthy sides(P>0.05).2.Compared with the healthy side,on average,the simulated hip flexion decreased significantly by 27.0°and the hip MIR-90°decreased significantly by 20.3°on the affected side after fracture(P<0.05).Regression analysis showed that femoral anteversion angle,ACEA and displacement of the femoral head center had a significant influence on hip ROM,especially the anteversion angle.When the anteversion angle decreased by more than 7.1°,the hip flexion would decrease by at least 20%.3.The points of FAI distributed more widely on the fracture side.Compared with the healthy side,the impact points extended outward and upward in hip flexion and extended inwardly in hip MIR-90°on the affected side.Conclusions After a valgus impacted femoral neck fracture,if the femoral anteversion angle has been decreased by more than 7.1°,the hip ROM can be greatly influenced and the points of FAI can be distributed more widely.Therefore,reduction should be recommended before internal fixation of the fracture.