Orthopaedic Department, University Hospital of Patras, Patras, Greece.
Laboratory of Technology and Strength of Materials, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras, Greece.
Trials. 2019 Jun 17;20(1):359. doi: 10.1186/s13063-019-3445-x.
Total hip replacement has recently followed a progressive evolution towards principles of bone- and soft-tissue-sparing surgery. Regarding femoral implants, different stem designs have been developed as an alternative to conventional stems, and there is a renewed interest towards short versions of uncemented femoral implants. Based on both experimental testing and finite element modeling, the proposed study has been designed to compare the biomechanical properties and clinical performance of the newly introduced short-stem Minima S, for which clinical data are lacking with an older generation stem, the Trilock Bone Preservation Stem with an established performance record in short to midterm follow-up.
METHODS/DESIGN: In the experimental study, the transmission of forces as measured by cortical surface-strain distribution in the proximal femur will be evaluated using digital image correlation (DIC), first on the non-implanted femur and then on the implanted stems. Finite element parametric models of the bone, the stem and their interface will be also developed. Finite element predictions of surface strains in implanted composite femurs, after being validated against biomechanical testing measurements, will be used to assist the comparison of the stems by deriving important data on the developed stress and strain fields, which cannot be measured through biomechanical testing. Finally, a prospective randomized comparative clinical study between these two stems will be also conducted to determine (1) their clinical performance up to 2 years' follow-up using clinical scores and gait analysis (2) stem fixation and remodeling using a detailed radiographic analysis and (3) incidence and types of complications.
Our study would be the first that compares not only the clinical and radiological outcome but also the biomechanical properties of two differently designed femoral implants that are theoretically classified in the same main category of cervico-metaphyseal-diaphyseal short stems. We can hypothesize that even these subtle variations in geometric design between these two stems may create different loading characteristics and thus dissimilar biomechanical behaviors, which in turn could have an influence to their clinical performance.
International Standard Randomized Controlled Trial Number, ID: ISRCTN10096716 . Retrospectively registered on May 8 2018.
全髋关节置换术最近朝着骨和软组织保护手术的原则不断发展。在股骨假体方面，已经开发出不同的假体设计来替代传统的假体，并且人们对非骨水泥股骨假体的短型假体重新产生了兴趣。基于实验测试和有限元建模，本研究旨在比较新引入的 Minima S 短柄股骨假体和具有既定短期至中期随访记录的旧一代 Trilock Bone Preservation Stem 假体的生物力学性能和临床性能。
方法/设计：在实验研究中，将使用数字图像相关（DIC）技术评估通过皮质表面应变分布测量的股骨近端力的传递，首先在非植入股骨上进行，然后在植入的假体上进行。还将开发骨、假体及其界面的有限元参数模型。经过生物力学测试测量验证后，将植入复合股骨的表面应变有限元预测用于辅助通过得出关于所开发的应力和应变场的重要数据来比较假体，这些数据无法通过生物力学测试来测量。最后，还将对这两种假体进行前瞻性随机对照临床研究，以确定（1）在 2 年随访时使用临床评分和步态分析来确定它们的临床性能（2）使用详细的放射学分析来确定假体的固定和重塑（3）并发症的发生率和类型。
我们的研究将首次比较两种设计不同的股骨假体的临床和影像学结果以及生物力学特性，这两种假体在理论上被归类为同一主要类别中的颈干骺端短型假体。我们可以假设，即使这两种假体在几何设计上存在细微差异，也可能会产生不同的载荷特征，从而导致不同的生物力学行为，这反过来又会对它们的临床性能产生影响。
国际标准随机对照试验编号，ID：ISRCTN16143535。于 2018 年 5 月 8 日进行了回顾性注册。
