Ceramic Materials in Total Joint Arthroplasty

Bearing surfaces made of ceramic materials are an alternative to metal-on-polyethylene (PE) articulations in total hip arthroplasty and total knee arthroplasty. The advantage of ceramic surfaces in total joints is the reduction in wear rates compared with metal-on-PE. Lower wear rates result in a decreased volume of wear particles produced by the articulating surfaces. In theory, this should reduce the risk of periprosthetic osteolysis and premature implant loosening, thereby contributing to the longevity of prosthetic joints. In addition to ceramics, other alternative bearings, such as highly cross-linked PE and metal-on-metal, also offer decreased wear rates when compared with metal-on-PE articulations in total joint arthroplasty. Alumina and zirconia ceramics are familiar to orthopedic surgeons because both materials have a long history of use in total joint bearings. Alumina-on-alumina ceramic total hip articulations are now available in the United States from several implant manufacturers. Composite materials made by combining alumina and zirconia, metal-on-ceramic articulations, and new ceramic materials will offer even more choices as the search for the ideal bearing combination in total joint arthroplasty continues. The purpose of this article is to review the material properties, clinical applications, evolution, and limitations of the ceramic materials used in total joint bearings

Vascular deprivation-induced necrosis of the femoral head of the rat. An experimental model of avascular osteonecrosis in the skeletally immature individual or Legg-Perthes disease

The blood supply of rats' femoral heads was severed by cutting the ligamentum teres and stripping the periostium. Histologically, necrosis of the marrow was apparent on the 2nd postoperative day, necrosis of the bone on the 5th postoperative day and fibrous ingrowth on the 7th postoperative day. During the following 5 weeks, progressive resorption of the intertrabecular necrotic debris and necrotic bony trabeculae and subchondral bone plate and, concurrently, appositional and intramembranous new bone formation resulted in remodeling of the femoral heads. In 2 of 7 femoral heads, replacement of the necrotic bone by viable bone was complete at the 42-day postoperative interval. Also, the articular cartilage of the deformed and flattened femoral heads was undergoing degenerative changes. Reduplicating the pathogenically inferred clinical settings of blood supply deprivation, it is proposed that this model, in a small laboratory animal, satisfies the requirements sought for preclinical studies of treatment modalities of avascular osteonecrosis in man