DEVELOPMENT OF A CEMENTLESS HIP ENDOPROST HESIS - A CHRONOLOGICAL SUMMARY

SCHAWALDER and coworkers developed different types of cementless impla nted prosthesis systems to bypass the still existing problems with the cementing procedure. The applied prosthesis systems differed markedly from the common joint replacements by the design and the technique of implantation. The applied hollow cylinder principles for fixation of the prothesis have major and critical advantages. The production costs are relatively low, due to the rotational symmetry of the ''femoral h ead'' and the ''femoral head and neck'' titanium endoprosthesis design . The implantation is minimally destructive because the initial bone b ed can be preserved. The exterior thread of the prosthesis produces an excellent primary stability leading to an ankylotic metal-bone compou nd. The design and the surface of the prosthesis do not only allow a t hree dimensional force transmission but also a rapid and almost undist urbed revascularisation of the prosthesis bone bed. The absence of the cement and the ancylotic bone-metal compound do also allow the body t o counteract a possible infection at any place close to the implant. T he problems with infections become secondary. The threaded, perforated hollow cylinder shaft of the prosthesis with its treated surface allo ws a large contact surface with minimal metal parts. The almost delica te implant construction and the physical properties of the titanium ar e the major reasons for the elasticity of the implant which is compara ble to bone. Clinical research but also long-term results support the advantage of this principally different endoprosthesis.