The third generation of hip resurfacing commenced in the U.K. in the 1990’s with the BirminghamudHip Resurfacing system and is now becoming more commonplace as an attractive alternative forudyoung and active patients due to premature failure in total hip replacement in this patient group.udHowever the Swedish National Hip Arthroplasty Register (2010) suggests that premature failure ofudresurfacing arthroplasty may be more prevalent than first expected. The aim of this study is toudinvestigate, through Finite Element Analysis, the short, medium and long term performance of PolyudMethyl Methacrylate (PMMA) bone cement of the femoral component in hip resurfacingudarthroplasty. The study takes a forensic engineering approach, analysing the performance ofudPMMA bone cement in order to provide understanding, awareness and an insight into lifestyle options.udFinite Element Analysis explores and models the effect of resting periods during daily activities,udpatients’ bone quality and PMMA bone cement Young’s modulus on the PMMA bone cementudstresses within the femoral hip resurfacing component. Mechanical tests are used to illustrate the use of the Finite Element Analysis results.udContributing to knowledge, this study verifies the significance of high metal-on-metal friction due to resting periods, developing a dynamic FEA model to quantify the premature fatigue failure ofudPMMA bone cement, within the femoral component of hip resurfacing arthroplasty. A decrease inudbone quality added to the effect of resting periods increase the risk of PMMA fatigue failure and PMMA-metal interface failure due to an increase of PMMA tensile and shear stresses, suggesting that patients with low bone quality should avoid hip resurfacing procedures. The use of low PMMA Young’s modulus could greatly enhance the long term success of hip resurfacing arthroplasty generally and specifically reduce the risk of interface failure and PMMA bone cement failure due to resting periods and patient bone quality. Moreover, this study shows that the consequence of PMMA fatigue failure and PMMA-metal interface failure must be included in the design, patient selection, screening process, post-operative rehabilitation and long term lifestyle attributes.udThis study suggests that occupational therapists and patients with hip resurfacing arthroplastyudshould be aware of high metal-on-metal friction situations, which could lead to early failureudindicated by this research. The deleterious effect of resting periods indicated by this researchudcould be alleviated by appropriate re-initiation of synovial lubrication by movement prior to fulludloading. Recommendations for further work include the compilation of a PMMA bone-cement fatigue properties database and further development of the FEA modelling technique for application upon other arthroplasty procedures.
展开▼
