Institute of Medical and Biological Engineering, Mechanical Engineering, University of Leeds, Leeds, UK.
Ann Biomed Eng. 2024 May;52(5):1393-1402. doi: 10.1007/s10439-024-03464-6. Epub 2024 Mar 6.
Osteochondral grafting has demonstrated positive outcomes for treating articular cartilage defects by replacing the damaged region with a cylindrical graft consisting of bone with a layer of cartilage. However, factors that cause graft subsidence are not well understood. The aim of this study was to develop finite element (FE) models of osteochondral grafts within a tibiofemoral joint, suitable for an investigation of parameters affecting graft stability. Cadaveric femurs were used to experimentally calibrate the bone properties and graft-bone frictional forces for use in corresponding image-based FE models, generated from µCT scan data. Effects of cartilage defects and osteochondral graft repair were measured by examining contact pressure changes using further in vitro tests. Here, six defects were created in the femoral condyles, which were subsequently treated with osteochondral autografts or metal pins. Matching image-based FE models were created, and the contact patches were compared. The bone material properties and graft-bone frictional forces were successfully calibrated from the initial tests with good resulting levels of agreement (CCC = 0.87). The tibiofemoral joint experiment provided a range of cases that were accurately described in the resultant pressure maps and were well represented in the FE models. Cartilage defects and repair quality were experimentally measurable with good agreement in the FE model pressure maps. Model confidence was built through extensive validation and sensitivity testing. It was found that specimen-specific properties were required to accurately represent graft behaviour. The final models produced are suitable for a range of parametric testing to investigate immediate graft stability.
骨软骨移植通过用包含骨和软骨层的圆柱形移植物替换受损区域,已被证明对治疗关节软骨缺损具有积极的效果。然而,导致移植物下沉的因素尚未得到很好的理解。本研究的目的是开发适用于研究影响移植物稳定性的参数的胫骨股骨关节内骨软骨移植的有限元(FE)模型。使用尸体股骨进行实验校准骨特性和移植物-骨摩擦力,用于从 µCT 扫描数据生成相应的基于图像的 FE 模型。通过进一步的体外试验测量软骨缺损和骨软骨移植修复的效果,检查接触压力的变化。在这里,在股骨髁上创建了六个缺损,然后用骨软骨自体移植物或金属销进行治疗。创建了匹配的基于图像的 FE 模型,并比较了接触斑块。从初始测试中成功校准了骨材料特性和移植物-骨摩擦系数,具有很好的一致性(CCC=0.87)。胫骨股骨关节实验提供了一系列的情况,在产生的压力图中得到了准确的描述,并在 FE 模型中得到了很好的体现。通过在 FE 模型压力图中具有良好的一致性,对软骨缺损和修复质量进行了实验测量。通过广泛的验证和敏感性测试建立了模型的可信度。发现需要特定于标本的特性来准确表示移植物的行为。最终生成的模型适用于一系列参数测试,以研究即时移植物稳定性。