Bone and Joint Prostheses

Bone and Joint Prostheses,—Further assessments of the potential value of polysulphone in orthopaedic implants have been made. A total elbow replace- 

Mutschler, H. Meyer, and E, Plank, Zentralbi. Veterinaermed., Reihe.A, 1979, 26, 247. 

A useful collection of symposium papers under the general title Corrosion and Degradation of Implant Materials has been published by the American Society for Testing and Materials. In this, two separate studies of retrieved orthopaedic implants are presentedtogether with an account by Dumbleton of the literature on the use, primarily in Scandinavia, of polyoxymethylene (Delrin) for compK nents of total hip and total knee joint prostheses. 

Bone and Joint Prostheses.— The present state of the art in the field of joint replacement and complications arising with existing materials has been discussed by various authors. Attention continues to be paid to the mechanical testing of implants and implant materials, particularly with respect to various aspects of the bond strength of the bone/poly(methyl methacrylate) (cement) interface. A stress analysis of the human femur with implanted Charnley prostheses has been carried out.  

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

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