Joint implants

Hydroxyapatite (HA) coating on the surface of the hip stem and the acetabular cup is the most recent advancement in artificial hip joint implant technology. This substance is a form of calcium phosphate, which is sprayed onto the hip implant. It is a material found in combination with calcium carbonate in bone tissue, and bones can easily adapt to it. When bone tissue does grow into HA, the tissue then fixes the hip joint implant permanently in position. These HA coatings are only used in press-fit, noncemented implants. 

Biomaterials. Just as stem designs have evolved in an effort to develop an optimal combination of specifications, so have the types of metals and alloys employed in the constmction of total joint implants. Pure metals are usually too soft to be used in prosthesis. Therefore, alloys which exhibit improved characteristics of fatigue strength, tensile strength, ductihty, modulus of elasticity, hardness, resistance to corrosion, and biocompatibiUty are used. 

B.D. Ferris, A quantitative study of the tissue reaction and its relationship to debris production from a joint implant, British journal of experimental pathology, 71 (3) 367—373,1990. 

Neutrophils are also rapidly attracted to the site of a foreign body reaction, but likely persist in large numbers for only a few days. They generally reside within blood vessels, but in response to signals such as histamine, which increases vascular permeability, neutrophils enter the extravascular space through a process known as diapedesis. A recent study by Wozniak found that nitric oxide produced by neutrophils plays an important role in loosening of total joint implants.11... 

Using the cage implant system, Kim et al. successfully polymerized a phospholipid on to a solid substrate and found reduced adsorption of proteins such as albumin, fibrinogen, and IgG and also reduced macrophage adhesion.80 There has also been widespread interest in the use of PC coats for orthopedic joint implants as well as other biomedical applications.81 3... 

Wozniak W, Markuszewski J, Wierusz-Kozlowska M, Wysocki H. Neutrophils are active in total joint implant loosening. Acta Orthopaedica Scandinavica 2004, 75, 549-553. 

The most well characterized of the p38 kinases, the final MAPK phosphorelay pathway, is p38a, which is expressed by most cells and regulates the expression of many cytokines. Interleukin 1, IL-1, a product of inflammatory cells, has been implicated in modulating the response to mechanical loading in a number of tissues. IL-1 is a product of inflammatory cells thought to be involved in cartilage destruction in osteoarthritis and in bone resorption associated with total joint implant failure. 

Orthopaedic prosthesis Mechanism of wear of Ultra-high molecular weight polyethylene currently used in total hip and knee joint implants— see J. Mater. Set. 28 1045-1058 (1993). 

Periti P, Stringa G, Mini E. Comparative multicenter trial of teicoplanin versus cefazolin for antimicrobial prophylaxis in prosthetic joint implant surgery. Italian Study Group for Antimicrobial Prophylaxis in Orthopedic Surgery. Eur J Clin Microbiol Infect Dis 1999 18(2) 113-19. 

In 2003, an up-to-date summary of studies was edited by Epinette and Manley (2003), describing the state-of-the-art of hydroxyapatite coatings in orthopaedics as this stood at the close of 2002. This compilation of results was designed to help to answer the still somewhat hotly debated question of whether the favourable results achieved in the short term with this method of biologic fixation of total joint implants has withstood the test of time. The goal of Epinette and Manley s book was mainly to determine if the use of hydroxyapatite coatings for the fixation of orthopaedic implants to bone has been proven by the survivorship and satisfaction of those patients who had received hip and knee implants. 

These restrictions notwithstanding, yttria-stabilised zirconia polycrystal (Y-TZP) femoral heads presently make up about 25% of the total annual number of hip joint implants in Europe and 8% in the United States. Between 1985 and 2001 more than 400000 Y-TZP femoral heads were implanted worldwide. However, safety concerns continue to plague zirconia femoral heads. The U.S. Food and Drug Administration (FDA, 2013) issued a safety alert in August 2013 to orthopaedic surgeons that the French manufacturer St Gobain Desmarquest had recalled an unimplanted inventory of zirconia femoral heads that were found to fracture at a higher rate than expected in some patients 13-27 months after implantation. 

Millennium Research Group (2011b) European Small-Joint Implant Market to Grow from 160 Million to 250 Million by 2016. MRG News (Nov. 2). 

Gross, U. (1994) in Technical Principles, Design and Safety of Joint Implants (eds G.H. Buchhorn and H.G. Willert), Hogrefe Huber Publishers, Seattle, WA Toronto, Bern, Gottingen, pp. 255-258, ISBN 3-456-82161-1. 

SuNDEEMAN FW Je (1994) Biological monitoring of metal exposures from joint implants. In Buchhom GH and WUlert HG, eds. Technical Principles, Design, and Safety of Joint Implants, pp. 184-187. Hogrefe and Huber, Seattle. 

After qualification by acute and chronic biocompatibility and biodurability evaluations, clinical studies were conducted to confirm that the implants were highly durable. Medical grade high performance silicone elastomer has now become used in various biomedical applications including construction of flexible bone and joint implants as designed by Swanson ( 9) (Figures... 

Figure 6. Surgical placement of the flexible hinge finger joint implant. The metacarpal head is removed to create an appropriate joint space and the intramedullary canals are then prepared to accept the implant stems. When the implant is placed in position the stems fit securely in the intramedullary canals with the flexible hinge permitting 90° active motion. Joint space is maintained by transfer of the compressive forces of joint motion across the implant to cortical bone. Careful attention to reconstructions of tendons, ligaments, and joint capsules and postoperative therapy are very important in this procedure.

P. Bracco, E. Oral, Vitamin E-stabilized UHMWPE for total joint implants a review, Clin. Orthop. Relat. Res. 469 (2011) 2286-2293. 

Li S., and A.H. Burstein. 1994. Ultra-high molecular weight polyethylene. The material and its use in total joint implants. / Bone Joint Surg Am 76 1080-1090. 

Orthopedics Today. 1999. Guide to polyethylene in joint implants. Orthopedics Today, Slack, Inc., Oct-Nov. 

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