Mechanical Engineering Department, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
Med Eng Phys. 2013 Oct;35(10):1457-64. doi: 10.1016/j.medengphy.2013.03.020. Epub 2013 May 3.
Accurate computer modelling of the fixation of unicompartmental knee replacements (UKRs) is a valuable design tool. However, models must be validated with in vitro mechanical tests to have confidence in the results. Ten fresh-frozen cadaveric knees with differing bone densities were CT-scanned to obtain geometry and bone density data, then implanted with cementless medial Oxford UKRs by an orthopaedic surgeon. Five strain gauge rosettes were attached to the tibia and femur of each knee and the bone constructs were mechanically tested. They were re-tested following implanting the cemented versions of the implants. Finite element models of four UKR tibiae and femora were developed. Sensitivity assessments and convergence studies were conducted to optimise modelling parameters. The cemented UKR pooled R(2) values for predicted versus measured bone strains were 0.85 and 0.92 for the tibia and femur respectively. The cementless UKR pooled R(2) values were slightly lower at 0.62 and 0.73 which may have been due to the irregularity of bone resections. The correlation of the results was attributed partly to the improved material property prediction method used in this project. This study is the first to validate multiple UKR tibiae and femora for bone strain across a range of specimen bone densities.
准确的单髁膝关节置换物（UKR）固定计算机建模是一种有价值的设计工具。然而，为了对结果有信心，模型必须经过体外力学测试来验证。对 10 个具有不同骨密度的新鲜冷冻尸体膝关节进行 CT 扫描，以获取几何形状和骨密度数据，然后由矫形外科医生植入非骨水泥内侧牛津 UKR。每个膝关节的胫骨和股骨上附着了 5 个应变片花，对骨结构进行了力学测试。然后在植入植入物的水泥版本后重新进行测试。开发了 4 个 UKR 胫骨和股骨的有限元模型。进行了敏感性评估和收敛性研究，以优化建模参数。水泥固定 UKR 的预测与测量骨应变的 R（2）值分别为胫骨和股骨的 0.85 和 0.92。非骨水泥 UKR 的 R（2）值略低，为 0.62 和 0.73，这可能是由于骨切除不规则所致。结果的相关性部分归因于本项目中使用的改进的材料性能预测方法。这项研究首次验证了多种 UKR 胫骨和股骨在一系列标本骨密度下的骨应变。
