摘要
目的研究全髋关节假体中聚乙烯内衬在髋臼不同植入方向和不同直径股骨头时,在平地行走和上楼等不同运动状态下关节面白的接触应力水平。方法建立金属髋臼、聚乙烯内衬以及相应直径股骨头的三维有限元模型,在股骨头中心加载关节负荷,非线性接触弹塑性分析内衬关节面的接触应力。结果髋臼植入的前倾、外展角度不同和股骨头直径变化以及不同运动状态对内衬应力水平均有一定的影响。上楼等高负重运动以及股骨头直径减小均可增加内衬的应力,直径小于28 mm的股骨头在上楼时内衬的应力水平可超过聚乙烯的屈服强度;髋臼前倾(0°～30°)和外展(30°～60°)角度变化对平地行走时内衬应力水平的波动在20%左右,应力水平均低于其屈服强度,但是在上楼时前倾和外展角度的增加均可增加内衬的应力,前倾大于15°时应力峰值均超过聚乙烯的屈服强度。结论全髋关节置换手术可考虑选择股骨头直径较大的髋臼假体,并且严格控制髋臼植入在安全范围内,术后避免或减少上楼等高负重活动均有利于减少对内衬的破坏。
Objective To determine the variation in contact stress on polyethylene liner of met-al-backed acetabular components in cases of different cup orientation and femoral head prosthesis diameter un-der different gait states including heelstriking, midstance, toe off and upstairs. Methods Three-dimen-sional finite element models of metal-backed acetabular components and corresponding ultra-high molecular weight polyethylene liners with femoral head diameters of 22 to 32 mm were developed. With the various stress loaded through the head center, contact force of articular surface was analyzed by nonlinear contact elasto-plastic finite element model. Results The cup orientation by different anteversion and/or abduction angles with different head diameters under various loading states affected the resulting contact stress markedly. Liner stress level increased with higher loading states like upstairs and/or smaller femoral head diameter. The peak liner contact stress values were found beyond the yield stress of polyethylene in femoral head smaller than 28 mm under upstairs loading. During walking at same speed on flat ground, the differ-ence of anteversion (0°-30°) and abduction (30°-60°) raised contact stress level of polyethylene liner fluctu-ating within 20% approximately, and all of the peak stress values were less than the yield stress of polyethy-lene. But under upstairs loading state, liner contact stress was found to increase either anteversion or abduc-tion angles. When anteversion angle exceed 15° with various abduction angles (30°-60°), the peak contact stress was all beyond yield stress of polyethylene. Conclusion Among the various designs and operative procedures available for surgeon to select, larger head diameter and proper orientation should be considered for the sake of efficient decrease of the liner contact stress. For patients after total hip arthroplasty, it is nec-essary to avoid or at least reduce higher loading activities.
出处
《中华骨科杂志》
CAS
CSCD
北大核心
2004年第4期211-215,共5页
Chinese Journal of Orthopaedics
