Clinical experience with mueller total hip endoprostheses of different design and material

Abstract

Patients of the Orthopaedic University Hospital in Frankfurt operated between 1970 and 1977 were examined to control the success of implantations of total hip endoprostheses. Ninety-three percent of totally 1497 implanted hip prostheses are Müller standard type, additionally there have been implanted 44 Weber-Huggler prostheses and 54 special long stem prostheses. During the follow-up period of 10 years 7.4% of the primarily implanted prostheses had to be revised. The reasons for revision were loosening of the stem and/or socket in 56% of the cases, 20% infections, 14% technical errors and in 11% of the cases fractures of the stem occured. Fifty-two percent of the implanted Weber-Huggler prostheses with rotational ball heads made of polyester had to be revised in the meantime, 78% of the cases because of loosening of the prosthetic components. It could be shown that the number of infected cases could be diminished after introduction of an ultraclean air operating box. The change of the cross section of the Müller-type-stem from a round medial wedge to a flat one and the introduction of CoNiCrMo wrought alloy Protasul-10 instead of CoCrMo cast alloy Protasul-2 as stem material in 1973 resulted in a much smaller rate of loosened prostheses without fractures of the forged Protasul-10 stems. During the 6 examined years there has been no fracture of a prosthetic stem made of Protasul-10.

Mechanical factors in loosening of Christiansen and Charnley arthroplasties

“…In fact, the Christiansen prostheses with a long neck had a greater tendency toward medial migration than the heads with medium or short necks in our series. Similar observations have been made by Willert et al ( 1980) concerning different designs of Miiller total hip prostheses. When calculating a total offset as a sum of the structural offset of the Christiansen prosthesis and the offset resulting from the position of the stem, we could substantiate this theory further, demonstrating increased frequency of cement fractures and medial migration with increased total offqet due to long neck and varus position.…”

“…Thus, insertion of the stem in a varus position was more common in the Christiansen than in the Charnley group. Varus position has previously been found to predispose to loosening (Beckenbaugh & Ilstrup 1978, Willert et al 1980 Willert et al 1980). We observed that, to give maximal protection against loosening, the cement mantle has not only to cover the total length of the prosthetic stem but also to extend from cortical wall to cortical wall of the medullary canal.…”

Stem fracture with the Exeter prosthesis 3 of 27 hips followed for 10 years

“…Apart from one report of 11% stem fractures with the Muller prosthesis of the earlier design (Martens et al 1974), less than 5% of stem fractures have been reported with other prostheses (Chamley 1975, Carlsson et al 1977, Willert et al 1980, Chao and Coventry 1981, Wroblewski 1982, Ritter and Campbell 1986, Amstutz et al 1990. Munuera and GarciaCimbrelo 1990.…”

An In Vivo Study of the Host Response to Starch‐Based Polymers and Composites Subcutaneously Implanted in Rats

“…Unpredictable adverse reactions to some commonly used traditional implants have been reported by a number of research groups. [3][4][5][6][7] Key factors in device failure are believed to be the generation of wear particles and the biological response to them in periprosthetic tissues [2,4] as well as the degradation products of biodegradable materials, both resulting in osteolytic reactions. [5,6,8] The presence of activated macrophages [9][10][11][12][13] or foreignbody giant cells, [9,11,13] and the formation of a fibrous capsule [14,15] are tissue-specific responses that have been the focus of investigation in the evaluation of biomedical implants.…”