摘要
目的建立骨质疏松性改良Evans分型Ⅲ型股骨转子间骨折的有限元模型，比较动力髋螺钉（DHS）和股骨近端防旋髓内钉（PFNA）内固定在不同表观骨密度和载荷下的生物力学特性。方法选择1例改良Evans分型为Ⅲ型的老年股骨转子间骨折患者，男性，年龄为75岁，身高172cm，体质量为70kg。对患者股骨中上2／3段进行cT扫描，建立骨折模型并予虚拟复位，分别在此模型上搭载DHS（模型I组）和PFNA（模型Ⅱ组）两种内固定物。每组分别考虑7种表观骨密度（70％、80％、90％、100％、110％、120％、130％的表观骨密度）及3种载荷（0．5、1．0、3．0倍体质量）下的受力情况，共有42种工况。比较各种条件下两组固定模型的股骨VonMises应力峰值、内固定物VonMises应力峰值及股骨单元失效率。结果在同一载荷下，模型Ⅰ组股骨及内固定物所承受应力、股骨单元失效率均大于模型Ⅱ组，差异有统计学意义（P〈0．05）；同一模型随着载荷的增加，股骨及内固定物所承受的应力、股骨单元失效率均上升，差异有统计学意义（P〈0．05）。在3．0倍体质量载荷、70％表观骨密度下，模型I组和模型Ⅱ组的股骨最大应力值分别为84．702、38．986MPa，内固定物最大应力值分别为952．557、580．134MPa，股骨单元失效率分别为5．25％、7．99×10。％。结论对于骨质疏松性改良Evans分型Ⅲ型股骨转子间骨折，PFNA固定较DHS固定具有明显的生物力学优势，固定强度更好，且不易导致内固定失效。
Objective To compare biomechanical characteristics of dynamic hip screw （DHS） versus proximal femoral nail anti-rotation （PFNA） in fixations under different apparent bone densities and loads in a three-dimensional finite element model of osteoporotic intertrochanteric fracture of the femur （modified E- vans-Jensen type M ）. Methods CT was used to scan the upper and middle femur of an aged male with osteoporotic intertroehanteric fracture （modified Evans-Jensen type Ⅲ ） . He was 75 years old, 172 cm in height and 70 kg in weight. Based on the CT scans, fracture models were created to simulate reductions and DHS internal fixation （Model Ⅰ group） and PFNA internal fixation （Model Ⅱ group）. Each group was sub- jected to 7 apparent bone densities （70%, 80%, 90%, 100%, 110%, 120% and 130%） and 3 loads （0. 5, 1.0 and 3.0 times of weight）. The 2 model groups were compared under all working conditions in terms of the maximum Von Mises stress of the femur, the maximum Von Mises stress of internal fixator and femoral element failure ratio, Results Under the same load, the stresses and femoral element failure ratio sus- tained by Model Ⅰ group were all significantly greater than by the Model Ⅱ group （ P 〈 0. 05 ）. In the same model group, the stresses and femoral element failure ratio sustained by the femur and the internal fixator increased significantly with the increase of load （ P 〈0.05） . Under the working condition of 3.0 times of weight load and 70% of apparent bone density, Model Ⅰ group and Model Ⅱ group respectively had the femoral maximum Von Mises stresses of 84. 702 MPa and 38. 986 MPa, the maximum Von Mises stresses of internal fixator of 952. 557 MPa and 580. 134 MPa, and the femoral element failure ratios of 3.25% and 7.99 × 10-3%. Conclusion For osteoporotic intertrochanteric fracture of the femur （modified E- vans-Jensen type Ⅱ ）, PFNA internal fixation system has an obvious biomechanical advantage over DHS, because the former may provide greater fixation stability than the latter, and unlikely leads to internal fixation failure.
出处
《中华创伤骨科杂志》
CAS
CSCD
北大核心
2012年第10期876-882,共7页
Chinese Journal of Orthopaedic Trauma
基金
上海市科委生化重点科技攻关项目（08411950600）
上海市自然科学基金重点项目（10ZRl427800）
关键词
髋骨折
骨钉
骨质疏松
有限元分析
生物力学
Hip fractures
Bone nails
Osteoporosis
Finite element analysis
Biome-chanics
