Joints Prosthetic

When a human joint has been destroyed or damaged by disease or injury, surgical replacement, also addressed to as arthroplasty, is normally required. A total joint replacement includes components that simulate a natural human joint (16)  

Three basic problems may cause a total joint replacement to fail or to have a limited service life. The first problem, arises, because the elastic modulus of the stem greatly exceeds that of the bone. Flexural loading caused by walking creates local cyclic stress concentrations due to the non-compliance of the stem. These stresses can be intense and even severe enough to cause death of local bone cells. If this 

The second basic problem is known as ball-cup friction and wear. It results from frictional wear between the hemispherical bearing and the polished spherical ceramic or metal ball attached to the stem. The third problem is addressed to as sub-surface fatigue. It results from the brittleness of the UHMWPE bearing and the tendency of the UHMWPE bearing to fail under reciprocating applied loads. 

In summary, the reaction to these particles includes inflammation and deterioration of the tissues, particularly the bone to which the prosthesis is anchored. Eventually, the prosthesis becomes painfully loose and must be replaced (12). 

Implantable prosthetic bearings may be constructed from a composite material having a first layer and a second layer (20). The first layer has an articulating surface defined therein, whereas the second layer has an engaging surface defined therein for engaging either another prosthetic component or the bone itself. The first layer is constructed of a UHMWPE, whereas the second layer is constructed of a copolymer of ethylene and an acrylate. 

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In 1971 a metal-backed polyethylene acetabular cup was introduced. This cup provided an eccentric socket which was replaceable, leaving the metal and replacing only the polyethylene. Because of the success of this component, metal-backed high density polyethylene (HDPE) liner is standard for prosthetic acetabular components. Research confirms that metal-backing reduces the peak stresses in the bone cement, and that HDPE forms a successfiil articulating surface for the prosthetic joint. 

Chemoprophylaxis has been extended to other surgieal proeedures where the risk of infection m be low but its oecurrence has serious eonsequences. This is especially frue for the implantation of prosthetic joint or heart valves. These are major surgical procedures and although infeetion be infiequent its eonsequences are serious and on balance the use of chemoprophylaxis is cost-effeetive. 

Class 11b, for example, urethral stents, insulin pens, devices supplying ionising radiation, prosthetic joint replacements, intraocular lenses, maxillofacial implants... 

Prosthetic Joints (hip, knee, shoulder, elbow, wrist)... 

A table of polycrystalline diamond may be manufactured and later attached to a prosthetic joint in a location such that it will form a bearing surface. The attachment could be performed by welding, brazing, or by the use of fasteners such as screws, bolts, or rivets (17). 

Biomaterials are materials foreign to the human body that are used in medicine to replace, support or restore body function. Applications range from central venous and urinary catheters to more complex devices such as prosthetic joints and heart valves. The risk of biomaterial centered infection (BCI) is a key factor limiting their use [1]. The incidence of this type of infections varies for each application for instance 4% for hip prostheses [2] and 10-20% for urinary catheters (see Table 1). In BCI microorganisms are present in close association with the biomaterial surface forming a so-called biofilm. Different species of microorganisms are found in BCI that are often commen-... 

Insertion of prosthetic joints. Chemoprophylaxis is justified because infection (Staphylococcus aureus, coagulase-negative staphylococci and coliforms are commonest) almost invariably means that the artificial joint, valve or vessel must be replaced (various regimens are used, with inclusion of vancomycin when the local MRSA prevalence is high). Single perioperative doses of appropriate antibiotics with plasma... 

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. 

A wide variety of medical devices are increasingly used in clinical practice. These range from vasculature and urinary catheters, prosthetic joints and heart valves, shunts and stents for improving the flow of CSF, blood or bile according to their site of... 

Acute and chronic osteomyelitis Septic arthritis/bursitis Prosthetic joint infections IV line infection Infective endocarditis... 

Another type of infectious arthritis occurs following prosthetic joint surgery. With these infections, the erythrocyte sedimentation rate usually is elevated, although a leukocytosis often is absent. Infections that result from postoperative contamination usually become apparent within 1 year of surgery. 

Kaandorp CJ, Dinant HJ, van de Laar MA, et al. Incidence and sources of native and prosthetic joint infections A community based prospective survey. Ann Rheum Dis 1997 56 470-475. 

As a metal, zirconium is used in bone and muscle implant materials. The combination of mechanical properties and excellent biocompatibility makes tetragonal zirconia polycrystal (TZP) ceramics one of the best biomaterials for prosthetic joints. (Covacci et al. 1999). 

The typical prosthesis control system consists of a Bowden cable with appropriate terminal fittings. The terminal fittings are used to anchor one end of the cable to a body-harness, and the other end to the prosthetic component to be controlled. Between the two end points, the cable crosses the prosthetic joint to be controlled and the physiolog-... 

In position control the position of the prosthetic joint is proportional to the input amount/intensity. The input amount/intensity might be the position of another physiological joint or a force level. If the position of another joint is used as the input then the system is known as a position actuated, position servomechanism. If the amount of force applied by some body part is the input, then the system is a force actuated, position servomechanism. An example is die power steering of a car. Here, the position of the steering wheel is related directly (proportional) to the position of the front wheels. Such a system is an example of a position follower (the position of the wheels follows the position of the steering wheel) or a position servomechanism. 

McKellop, H., Clarke, I., Markolf, K. and Amstutz, H. (1981) Friction and wear properties of polymer, metal, and ceramic prosthetic joint materials evaluated on a multichannel screening device. J. Biomed. Mat. Res., 15, 619-653. Compilation of laboratory tribological studies of currently used orthopaedic bearing materials. Presents a critical discussion of work by others and that of the authors. Data presented in this manuscript are commonly referred to by the orthopaedic tribology community. 

Saikko, V. (1993) Wear and friction properties of prosthetic joint materials evaluated on a pin on flat apparatus. Wear, 166, 169-178. 

Saikko V (1998), A multidirectional motion pin-on-disk wear test method for prosthetic joint materials , J Biomed Mater Res, 41, 58-64. 

Lentino JR. Prosthetic joint infections bane of orthopedists, challenge for infectious disease specialists. Clin Infect Dis 2003 36(9) 1157—61. 

Dale H, et al. Increasing risk of prosthetic joint infection after total hip arthroplasty 2,778 revisions due to infection after 432,168 primary THAs in the Nordic Arthroplasty Register Association (NARA). Acta Orthop 2012 83(5) 449—58. 

McGee MA, Howie DW, Costi K, Haynes DR, Wildenauer Cl, Pearcy MJ, et al. Implant retrieval studies of the wear and loosening of prosthetic joints a review. Wear 2000 241 158-65. 

Liao Y-S, Benya PD, McKellop HA. Effect of protein lubrication on the wear properties of materials for prosthetic joints. J Biomed Mater Res 1999 48 465-73. 

Sawae Y, Murakami T, Chen J. Effect of synovia constituents on friction and wear of ultra high molecular weight polyethylene (UHMWPE) sliding against prosthetic joint materials. Wear 1998 216 213-9. 

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