[New biomaterials in orthopedics]

Abstract

To develop new materials for articular prostheses seems particularly desirable since at present these do not appear to last for more than 1 or 2 decades. Improvements in our knowledge of prosthesis degradation has resulted in new, so-called "biomaterials" being proposed to cope with the various factors involved in disinsertion of artificial joints, viz, body tolerance to debris from wear or corrosion (biocompatibility), mechanical properties of the material, such as resistance to fatigue and wear and elasticity (biocompetence) and mechanical principles underlying arthroplasties (biomechanics). Current trends therefore are towards titanium alloys which are both resistant and similar to bone in elasticity, towards friction torques producing fewer or better tolerated debris (aluminium-coated polyethylene) and towards better means of fixation. Owing to the great complexity of tolerance mechanisms and to the functional character of orthopaedic surgery, very stringent testing is required before new products are in clinical use. While these products are slowly made available to surgeons, many significant improvements in existing materials (polyethylene and cements) are being achieved.