骨水泥髓内支撑与髓内钉治疗骨质疏松性肱骨近端骨折生物力学特性比较

A comparative study of the finite element analysis of bone cement intramedullary support and intramedullary nail in the treatment of osteoporotic proximal humerus fractures

目的应用有限元分析技术,比较外侧锁定钢板联合聚甲基丙烯酸甲酯(PMMA)骨水泥髓内支撑、外侧锁定钢板联合硫酸钙(CSC)骨水泥髓内支撑及Multiloc髓内钉治疗骨质疏松性肱骨近端骨折的生物力学特性指标。方法在1名老年骨质疏松女性(69岁,骨密度T值为-2.6)志愿者肱骨CT数据基础上建立骨缺损肱骨近端骨折的三维有限元模型,分别将外侧锁定钢板联合PMMA骨水泥髓内支撑(LLP-PMMA组)、外侧锁定钢板联合CSC骨水泥髓内支撑(LLP-CSC组)、Multiloc髓内钉(Multiloc组)3种不同内固定系统与骨折模型进行装配组合。模拟肱骨近端受力情况,对模型施加外展、内收、屈伸及旋转载荷。通过比较各组模型内植物的结构刚度、最大应力及应力分布、骨折断端位移及扭转角度评估不同内固定系统的力学稳定性。结果与Multiloc组比较,LLP-PMMA组和LLP-CSC组内收、外展、屈伸、逆时针旋转、顺时针旋转载荷下对应的结构刚度更强。在矢量载荷下,LLP-PMMA组和LLP-CSC组的内植物最大应力更小;在旋转载荷下,Multiloc组的内植物应力分布更均匀,最大应力更小。与Multiloc组比较,LLP-PMMA组和LLP-CSC组内收、外展、屈伸、逆时针旋转、顺时针旋转载荷下对应的断端位移和扭转角度更小。结论从有限元分析上看,外侧锁定钢板联合解剖状骨水泥髓内支撑占位器加强固定系统相较于联合Multiloc髓内钉固定系统具有更强的髓内支撑效果,生物力学性能更佳。

Objective To compare the biomechanical properties of lateral locking plate combined with polymethyl methacrylate(PMMA)bone cement and calcium sulfate(CSC)bone cement and Multiloc intramedullary nail in the treatment of osteoporotic proximal humerus fractures by finite element analysis.Methods A three-dimensional finite element model of proximal humerus fracture with bone defect was established on the basis of humerus CT data of an elderly osteoporotic female(69 years old,bonemineraldensity T-value-2.6)volunteer.Three different internal fixation systems,namely lateral locking plate combined with PMMA bone cement intramedullary support(LLP-PMMA group),lateral locking plate combined with CSC bone cement intramedullary support(LLP-CSC group)and Multiloc intramedullary nail(Multiloc group),were assembled and combined with fracture models,respectively.To simulate the stress situation of the proximal humerus,the model was subjected to abduction,adduction,flexion and rotation loads.The mechanical stability of different internal fixation systems was evaluated by comparing the structural stiffness,maximum stress and stress distribution,fracture displacements and torsion angles of plants in each model.Results Compared with Multiloc group,LLP-PMMA group and LLP-CSC group had stronger structural stiffness under adduction,abduction,flexion,counterclockwise rotation and clockwise rotation loads.Under vector load,LLP-PMMA group and LLP-CSC group had lower endophytic maximum stress,while under rotational load,Multiloc group had more uniform endophytic stress distribution and lower maximum stress.Compared with Multiloc group,LLP-PMMA group and LLP-CSC group had smaller displacements and torsion angles of broken ends under adduction,abduction,flexion,counterclockwise rotation and clockwise rotation loads.Conclusion From the perspective of finite element analysis,the lateral locking plate combined with anatomic bone cement intramedullary support holder has better biomechanical properties than Multiloc intramedullary nail in the treatment of osteoporotic proximal humerus fractures,and can provide stronger and more direct intramedullary medial column support.