Li Junyan, Hua Xijin, Jin Zhongmin, Fisher John, Wilcox Ruth K
Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK.
Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK.
Med Eng Phys. 2014 Nov;36(11):1449-54. doi: 10.1016/j.medengphy.2014.05.014. Epub 2014 Jun 21.
Hip hemiarthroplasty is a common treatment for femoral neck fracture. However, the acetabular cartilage may degenerate after hemiarthroplasty leading to postoperative failure and the need for revision surgery. The clearance between the acetabular cartilage and head of the prosthesis is one of the potential reasons for this failure. In this study, the influence of joint clearance on the biomechanical function of a generic hip model in hemiarthroplasty was investigated using biphasic numerical simulation. Both a prolonged loading period of 4000 s and dynamic gait load of 10 cycles were considered. It was found that a larger clearance led to a higher stress level, a faster reduction in load supported by the fluid and a faster cartilage consolidation process. Additionally, the mechanical performance of the acetabular cartilage in the natural model was similar to that in the hemiarthroplasty model with no clearance but different from the hemiarthroplasty models with clearances of 0.5mm and larger. The results demonstrated that a larger clearance in hip hemiarthroplasty is more harmful to the acetabular cartilage and prosthesis heads with more available dimensions (i.e. smaller increments in diameter) could be manufactured for surgeons to achieve a lower clearance, and reduced contact stress in hemiarthroplasty surgeries.
髋关节半关节置换术是股骨颈骨折的常见治疗方法。然而，半关节置换术后髋臼软骨可能会退化，导致术后失败并需要翻修手术。髋臼软骨与假体头部之间的间隙是导致这种失败的潜在原因之一。在本研究中，使用双相数值模拟研究了关节间隙对半关节置换术中通用髋关节模型生物力学功能的影响。研究考虑了4000秒的延长加载期和10个周期的动态步态负荷。结果发现，间隙越大，应力水平越高，流体支撑的负荷下降越快，软骨固结过程越快。此外，自然模型中髋臼软骨的力学性能与无间隙的半关节置换术模型相似，但与间隙为0.5毫米及以上的半关节置换术模型不同。结果表明，髋关节半关节置换术中较大的间隙对髋臼软骨更有害，并且可以制造更多可用尺寸（即直径增量更小）的假体头部，以便外科医生实现更小的间隙，并降低半关节置换术手术中的接触应力。
