Osseointegration of total hip arthroplasties: studies in humans and animals.
ABSTRACT Total hip replacement is a successful, time-proven surgical procedure for reconstruction of the arthritic hip joint. The state of the bone-implant interface is crucial to the long-term integration and durability of hip replacements whether cemented or cementless. This review summarizes current clinical implant retrieval and animal research in hip-joint reconstruction. Future research must attempt to extend the longevity of hip replacements to avoid complex revision surgery.
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ABSTRACT: Finite element models of orthopedic implants such as hip resurfacing femoral components usually rely on contact elements to model the load-bearing interfaces that connect bone, cement and implant. However, contact elements cannot simulate progressive degradation of bone-cement interfaces or osseointegration. A new interface element is developed to alleviate these shortcomings. This element is capable of simulating the nonlinear progression of bone-cement interface debonding or bone-implant interface osseointegration, based on mechanical stimuli in normal and tangential directions. The new element is applied to a hip resurfacing femoral component with a stem made of a novel biomimetic composite material. Three load cases are applied sequentially to simulate the 6-month period required for osseointegration of the stem. The effect of interdigitation depth of the bone-cement interface is found to be negligible, with only minor variations of micromotions. Numerical results show that the biomimetic stem progressively osseointegrates (alpha averages 0.7 on the stem surface, with spot-welds) and that bone-stem micromotions decrease below 10 microm. Osseointegration also changes the load path within the femoral bone: a decrease of 300 microepsilon was observed in the femoral head, and the inferomedial part of the femoral neck showed a slight increase of 165 microepsilon. There was also increased stress in the implant stem (from 7 to 11 MPa after osseointegration), indicating that part of the load is supported through the stem. The use of the new osseointegratable interface element has shown the osseointegration potential of the biomimetic stem. Its ability to model partially osseointegrated interfaces based on the mechanical conditions at the interface means that the new element could be used to study load transfer and osseointegration patterns on other models of uncemented hip resurfacing femoral components.Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine 03/2013; 227(3):209-20. · 1.42 Impact Factor
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ABSTRACT: The improvement of bone ingrowth into prosthesis and enhancement of the combination of the range between the bone and prosthesis are important for long-term stability of artificial joints. They are the focus of research on uncemented artificial joints. Porous materials can be of potential use to solve these problems. This research aims to observe the characteristics of the new porous Ti-25Nb alloy and its biocompatibility in vitro, and to provide basic experimental evidence for the development of new porous prostheses or bone implants for bone tissue regeneration. The Ti-25Nb alloys with different porosities were fabricated using powder metallurgy. The alloys were then evaluated based on several characteristics, such as mechanical properties, purity, pore size, and porosity. To evaluate biocompatibility, the specimens were subjected to methylthiazol tetrazolium (MTT) colorimetric assay, cell adhesion and proliferation assay using acridine staining, scanning electron microscopy, and detection of inflammation factor interleukin-6 (IL-6). The porous Ti-25Nb alloy with interconnected pores had a pore size of 200 µm to 500 µm, which was favorable for bone ingrowth. The compressive strength of the alloy was similar to that of cortical bone, while with the elastic modulus closer to cancellous bone. MTT assay showed that the alloy had no adverse reaction to rabbit bone marrow mesenchymal stem cells, with a toxicity level of 0 to 1. Cell adhesion and proliferation experiments showed excellent cell growth on the surface and inside the pores of the alloy. According to the IL-6 levels, the alloy did not cause any obvious inflammatory response. All porous Ti-25Nb alloys showed good biocompatibility regardless of the percentage of porosity. The basic requirement of clinical orthopedic implants was satisfied, which made the alloy a good prospect for biomedical application. The alloy with 70% porosity had the optimum mechanical properties, as well as suitable pore size and porosity, which allowed more bone ingrowth.PLoS ONE 01/2013; 8(11):e79289. · 3.53 Impact Factor
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ABSTRACT: This study aimed to observe the osseointegration of hollow porous titanium prostheses (HPTP) loaded with cancellous bone matrix (CBM) in rabbits using histological and biomechanical perspectives. Experimental samples were implanted into the lateral femoral condyles of 66 New Zealand rabbits, allocated into the following groups: non-porous prosthesis group (Group A, n=22); HPTP group (Group B, n=22); HPTP+CBM group (Group C, n=22). The rabbits were sacrificed at 3, 8 and 12 weeks, postoperatively. X-ray analyses, microscopy techniques and morphological measurement software and mechanical tests were used for evaluation. At each time point, the tissues surrounding the implants were similar in all of the groups, with bony in-growth into the 2-mm round holes observed for the defects in Groups B and C. However, the internal bone formation was significantly better in Group C than in Group B at different time points (P<0.01). Biomechanically, the pull-out forces were significantly greater in Groups B and C than in Group A (P<0.01), with no difference between Groups B and C (P>0.05). These results suggest that bone can grow into the cavities of HPTP to achieve more stable locking fixation, and those osteogenic materials, such as CBM, can enhance osteogenesis to achieve better osseointegration between the implant and the host bone.Chinese Science Bulletin 57(20). · 1.37 Impact Factor