Further improvements in micro and macrogeometry smoothness and sphericity have also been made. Concerns of ceramic fracture seemed to have reduced with the improvement of ceramic quality and rests at approximately 1 per for a ten-year period. This hard material has lead to concerns that the less adaptable ostoeoporotic bone cannot adapt to it and fracture.
Total Hip Arthroplasty
Bizot et al. Elastic mismatch between bone and alumina ceramic or between bone and polymethylmethacrylate would be more pronounced in ostoeoporotic elderly patients. Osteolysis has still been described in the literature for this articulation. However, it appears, as with other articulations, that abnormal contact of components which occurs with poor positioning increases this risk. In vivo wear has been calculated to be less than 0. These results have been confirmed by Clarke for up to 14 million cycles. The friction coefficient of the alumina couple is 0. So that the wear that occurs in real life may not be as dramatically reduced.
Contrary to metal-on-PE articulations, the alumina-on-alumina combination does not favour a small head size. Also alumina femoral heads ranging from mm generate little debris as the bigger heads draw in more fluid for lubrication. It sometimes loosened and needed subsequent revision. Many methods of acetabular fixation have been tried, including the use of cement, press fit bulk alumina cups, and screwed in Titanium Ti shells. Sugano published his findings of 57 THA in patients with a mean follow-up of He reported radiological loosening in 3 femoral components and 16 ceramic acetabular components.
Wear of the socket was 0. Comparable results have also been published elsewhere.
Wear rate after the initial bedding-in period was 0. The mean linear wear rate was 0. They were gradually phased out by the mids in favour of metal-on-polyethylene bearings. This was mainly due to their higher loosening rates and concerns of biological reaction to the alloy constituents. Again concerns over osteolysis were thought to originate from polyethylene wear debris from metal-on-polyethylene articulations that led to the revival of metal-on-metal by the late s and its popularity seems to be increasing.
There were very few long-term published results concerning them, but studies noted their high revision rate due to component loosening. One such study published a follow-up of years, with a survival rate of Again it was noted that older patients in the study were more likely to have component loosening in the McKee-Farrar group. Other studies published metal-inducing tissue reaction, and this was attributed to the high rate of osteolysis noted at retrieval. This was despite the fact that wear rates from retrieval studies for these prostheses had shown very low wear rates.
In addition, metal ion release became more of a concern resulting in studies measuring their concentration in serum, blood and urine. These metallic wear particles have been shown to elicit an osteolytic response, but have also been found in para-aortic lymph nodes, the liver and the spleen. Granulomas in liver and spleen have also been found as a result of high concentrations of metal ions. However, again a higher rate of cancer development has not been proven in any study to date and long term risk of using the metal-on-metal bearings is not known.
The principal implications of the developments in all of these bearing surfaces in recent years are two-fold. Firstly, reduced wear has reduced debris causing osteolysis and aseptic loosening and, thus, increased the longevity of the THR. This would have the added advantages of reduced incidence of dislocation, a greater range of movement, and less impingement on the femoral neck.
Patients have different requirements from their THR implants depending on their age, gender and lifestyle and as long as there is this diversity, there will be a host of different implants made with different materials to cater to them. It is not possible to say that one bearing combination is better than the rest, but one must endeavour to tailor the selection of bearing surface to the patient to ensure satisfaction and the longest possible implant life.
However, better quality and more refined implants have resulted in most of the common bearing combinations mentioned in this paper having improved wear rates. What has been proven is that no matter which materials are being used in the THA, correct implantation techniques and alignment of components is the most important factor in avoiding early failure.
While focussing on the common bearing surfaces used in THAs, this paper does not extrapolate on different ways of fixing them to the femur or acetabulum or problems which might be encountered with patients with poor acetabular bone stock. It also does not explore the concept of resurfacing or other bone preserving techniques of surgery.
Other important concepts such as the size of femoral head and its effect on joint stability and range of motion have also not been covered here as they are outside the scope of this paper. While discussing wear characteristics of different bearing couples, it has not elaborated on the effect of implant position as a reason for increased wear because this is independent to the bearing couples and applies to all bearing surfaces. Measurement of polyethylene wear in acetabular components inserted with and without cement. A randomized trial. J Bone Joint Surg Am ; The Otto Aufranc Award.
Highly cross-linked polyethylene in total hip arthroplasty: randomized evaluation of penetration rate in cemented and uncemented sockets using radiostereometric analysis. Clin Orthop Relat Res ; Low-friction arthroplasty of the hip using alumina ceramic and cross-linked polyethylene. A ten-year follow-up report.
J Bone Joint Surg Br ; Larger diameter femoral heads used in conjunction with a highly cross-linked ultra-high molecular weight polyethylene: a new concept.
J Arthroplasty ; Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements. J Orthop Res ; Biomaterials ; Clinical performance of highly cross-linked polyethylenes in total hip arthroplasty. Clinical performance of a Durasul highly cross-linked polyethylene acetabular liner for total hip arthroplasty at five years.
Five-year experience with Crossfire highly cross-linked polyethylene. A randomized prospective evaluation of outcomes after total hip arthroplasty using cross-linked marathon and non-cross-linked Enduron polyethylene liners. Hamadouche M, Sedel L. Ceramics in orthopaedics. Christel PS.
Biocompatibility of surgical-grade dense polycrystalline alumina. Clin Orthop Relat Res Ceramics in total hip replacement. Boutin P. Experimental study and 1st clinical applications]. Prosthetic component failures in hip arthroplasty surgery. J Orthop Sci ; 5: Walter A.
On the material and the tribology of alumina-alumina couplings for hip joint prostheses. Clarke I. Stuctural ceramics in orthopaedics. Bone implant interface.
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Fritsch EW, Gleitz M. Ceramic femoral head fractures in total hip arthroplasty. Prudhommeaux F. Biomechanics International symposium on ceramics in medicine. World Scientific Publishing: New York; Meunier A. Clinical results of ceramic bearings in Europe. Symposium on alternative bearing surfaces in total joint replacement. Osteolysis in association with a total hip arthroplasty with ceramic bearing surfaces. The use of ceramic in prosthetic hip surgery. The state of the art. Chir Organi Mov ; Friction and wear properties of polymer, metal, and ceramic prosthetic joint materials evaluated on a multichannel screening device.
J Biomed Mater Res ; Ultra-low wear rates for rigid-on-rigid bearings in total hip replacements. Proc Inst Mech Eng H ; The various factors that contribute to bearing performance and control wear are thoroughly evaluated, and careful consideration is given to the technology and design solutions proposed with a view to producing low-wearing hip joints. This book will be of interest both to novices who want to learn more about the field and to experienced orthopaedic surgeons wishing to keep abreast of the latest developments.
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