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.
"However, all interfaces in these FE models simulate perfect adhesion on 100% of surface available for bonding. This perfect bonding is not representative of clinical situations, where spot-welding of implants is observed, and implants with 30 to 40% of their available surface bonded are clinically stable (Song et al., 1999). Such imperfect and uneven osseointegration could alter numerically obtained bone strains and change the outcome of implant simulations. "
"The surfaces of artificial joint prostheses are always treated with hydroxyapatite coating and rough surfaces, resulting in good integration of the bone and implant. However, this kind of treatment limits the combination of prosthesis and bone strength, as well as depth and scope, with a bone union rate of only 6% to 20% , , . Therefore, improving the bone ingrowth into prosthesis and enhancing the combination of the range between bone and prosthetic surface are important for long-term stability of artificial joints and the focus of research on uncemented artificial joints. "
[Show abstract][Hide abstract] 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 11/2013; 8(11):e79289. DOI:10.1371/journal.pone.0079289 · 3.23 Impact Factor
"The fixation stability of a cemented orthopedic implant and the host bone may be compromised either due to degradation of the bone cement itself, or there may be modeling and remodeling of the bone that occurs at the bone-implant interface . Eventually the failure of the implant occurs either due to stress shielding or host inflammatory response due to wear debris  . The initial fixation stability of an uncemented orthopedic implant is affected by the interfacial friction between the implant's surface and the host bone. "
[Show abstract][Hide abstract] ABSTRACT: This research involves the development of rapid manufacturing for patient-specific bone implants using a Subtractive Rapid Prototyping process. The geometry of segmental defects in bone, resulting from traumatic injury or cancerous tumor resection, can be reverse-engineered from medical images (such as CT scans), and then accurate defect fillers can be automatically generated in advanced synthetic or otherwise bioactive/biocompatible materials. This paper presents a general process planning methodology that begins with CT imaging and results in the automatic generation of process plans for a subtractive RP system. This work uniquely enables the rapid manufacturing of implant fillers with several key characteristics including; suitable bio-compatible materials and custom surface characteristics on specified patches of the filler geometry. This work utilizes a PLY input file, instead of the more common STL, since color texture information can be utilized for advanced process planning depending on whether the surface is fracture, periosteal or articular in origin. The future impact of this work is the ability to create accurate filler geometries that improve initial fixation strength and stability through accurate mating geometry, fixation planning and inter-surface roughness conditions.
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