Medical Device Research Institute, College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia.
J Orthop Res. 2020 Jul;38(7):1515-1522. doi: 10.1002/jor.24636. Epub 2020 Mar 4.
Aseptic loosening is the most common indication for revision of cementless acetabular cups and often depends on the primary stability achieved following surgery. Cup designs must be capable of achieving primary stability for a wide variety of individuals and surgical conditions to be successful. Typically, preclinical finite element (FE) testing of cups involves assessing the performance in a single patient and under a limited set of idealized conditions. The aim of this study was to assess the effect of patient and surgical parameters on the primary stability of an acetabular cup design in a set of subject-specific FE models. Interference fit was varied in a representative set of 12 patient-specific models of the implanted hemipelvis. Linear mixed models showed a significant association with micromotion for interference fit (P < .0001), acetabular bone elastic modulus (P < .001), native acetabular diameter (P = .03), and the interference fit-elastic modulus interaction (P = .01). There were no significant associations between the polar gap and any of the parameters considered. The significant interference fit-elastic modulus interaction suggests that increasing the interference fit in patients with low bone quality leads to a greater reduction in micromotion than in patients with higher bone quality. However, the significant association between percentage bone yielding and interference fit (P < .0001) suggests a higher periacetabular fracture risk at higher interference fits. This work supports the development of preclinical testing of cup designs for the broad range patients and surgical conditions a cup may face following surgery.
无菌性松动是翻修无水泥髋臼杯最常见的指征，通常取决于手术后获得的初始稳定性。杯设计必须能够为广泛的个体和手术条件实现初始稳定性，才能取得成功。通常，杯的临床前有限元（FE）测试涉及评估单个患者和一组理想化条件下的性能。本研究的目的是在一组特定于个体的 FE 模型中评估患者和手术参数对髋臼杯设计初始稳定性的影响。在一组 12 个植入半骨盆的患者特异性模型中，对过盈配合进行了变化。线性混合模型显示出与微动对过盈配合（P<0.0001）、髋臼骨弹性模量（P<0.001）、固有髋臼直径（P=0.03）和过盈配合-弹性模量相互作用（P=0.01）的显著相关性。极隙与任何考虑的参数之间均无显著相关性。过盈配合-弹性模量相互作用具有显著意义，表明在骨质量较低的患者中增加过盈配合会导致微动减少幅度大于骨质量较高的患者。然而，骨屈服百分比与过盈配合之间存在显著相关性（P<0.0001），表明在较高的过盈配合下，发生髋臼周围骨折的风险更高。这项工作支持为广泛的患者和手术条件下的杯设计开发临床前测试，以应对手术后杯可能面临的情况。
