Department of Biomedical Engineering, The University of Melbourne, Victoria, Australia.
Department of Biomedical Engineering, The University of Melbourne, Victoria, Australia; Department of Biomechanical Engineering, Delft University of Technology, Delft, Netherlands.
Clin Biomech (Bristol). 2020 Mar;73:201-212. doi: 10.1016/j.clinbiomech.2020.01.017. Epub 2020 Jan 20.
Osseointegrated implants for transfemoral amputees facilitate direct load transfer between the prosthetic limb and femur; however, implant loosening is a common complication, and the associated implant-bone loads remain poorly understood. This case study aimed to use patient-specific computational modeling to evaluate bone-implant interface loading during standing and walking in a transfemoral amputee with an osseointegrated implant prior to prosthesis loosening and revision surgery.
One male transfemoral amputee with an osseointegrated implant was recruited (age: 59-yrs, weight: 83 kg) and computed tomography (CT) performed on the residual limb approximately 3 months prior to implant failure. Gait analyses were performed, and the CT images used to develop a finite element model of the patient's implant and surrounding bone. Simulations of static weight bearing, and over-ground walking were then performed.
During standing, maximum and minimum principal strains in trabecular bone adjacent to the implant were 0.26% and -0.30%, respectively. Strains generated at the instant of contralateral toe-off and contralateral heel strike during walking were substantially higher and resulted in local trabecular bone yielding. Specifically, the maximum and minimum principal strains in the thin layer of trabecular bone surrounding the distal end of the implant were 1.15% and -0.98%, respectively.
Localised yielding of trabecular bone at the interface between the femur and implant in transfemoral amputee osseointegrated prosthesis recipients may present a risk of implant loosening due to periprosthetic bone fracture during walking. Rehabilitation exercises should aim to produce implant-bone loading that stimulates bone remodelling to provide effective bone conditioning prior to ambulation.
对于股骨截肢者，整合式骨内植入物可促进假肢与股骨之间的直接负载转移；然而，植入物松动是一种常见的并发症，相关的植入物-骨负载仍知之甚少。本病例研究旨在使用患者特异性计算建模来评估在假体松动和翻修手术之前，具有整合式骨内植入物的股骨截肢者在站立和行走期间的骨-植入物界面负载。
招募了一名男性股骨截肢者，他使用整合式骨内植入物（年龄：59 岁，体重：83 公斤），并在植入物失效前约 3 个月对残肢进行计算机断层扫描（CT）。进行步态分析，并使用 CT 图像开发患者植入物及其周围骨骼的有限元模型。然后对静态负重和地面行走进行模拟。
在站立时，紧邻植入物的小梁骨的最大和最小主应变分别为 0.26%和-0.30%。行走时对侧脚趾离地和对侧脚跟触地瞬间产生的应变要高得多，导致局部小梁骨屈服。具体来说，植入物远端周围的薄小梁骨的最大和最小主应变分别为 1.15%和-0.98%。
股骨截肢者整合式骨内假体接受者股骨和植入物之间界面处小梁骨的局部屈服可能会导致假体松动的风险，因为行走时会发生假体周围骨折。康复锻炼应旨在产生刺激骨重塑的植入物-骨负载，以在开始行走前提供有效的骨条件。
