Nine-year results of Müller cemented titanium Straight Stems in total hip replacement

Abstract

At the Orthopaedic Department of the University of Basel, a total of 540 cemented Müller titanium alloy (Ti6Al7Nb) Straight Stems were inserted between 1989 and 1993. A cohort of 120 consecutive patients (66 women, 54 men) with 126 prostheses operated on between March and December 1989 were followed clinically and radiologically in a prospective manner for a mean observation time of 9.1 years. In all cases, the Müller titanium alloy Straight Stem was combined with the senior author's (E.W.M.) Press-Fit Cup. The mean age of the patients at surgery was 66 (range 43-93) years. Fourty patients (41 hips) died, 9 were interviewed by telephone, none was 'lost to follow-up'. Seventy-one patients with 76 hip replacements were available for the follow-up. Four hips had been revised: two of them due to aseptic loosening of the femoral component, one because of a late infection--all after 9 years--and one owing to a periprosthetic fracture after 6 years. The 9-year overall survivorship is 96.8%, and for aseptic loosening of the stem 98.4%. None of the cups had to be revised for aseptic loosening. The clinical result (according to Merle d'Aubigné) was excellent and good in 88%, moderate in 8%, and poor in 4%. The radiological analysis showed no osteolysis or radiolucent lines in 59 prostheses (78%). Nine stems (12%) showed a radiolucent line. Focal osteolysis was detected in 8 cases (10%) in one or more Gruen zones. The distribution of the osteolyses shows that predominantly zones VII, VI, V, and II are affected in decreasing frequency. No osteolysis was detected on the acetabular side. Our results do not confirm the high rate of osteolysis and revisions with the Müller titanium alloy Straight Stem presented by some other institutions. The verdict on a specific endoprosthetic implant must be made by combined assessment of the design, the implant surface condition, the material, the cement, the cementing procedure and the operative technique. The statement made in earlier publications that cemented titanium alloy should not be used as a femoral stem prosthesis should be reconsidered.

Total hip replacement with a collarless polished cemented anatomic stem: clinical and gait analysis results at ten years follow-up

“…Linear radiolucency and isolated bone lysis at the cement-bone interface have been reported in up to 30 % of cases at long-term follow-up [14] and do not necessarily indicate loosening [15]. We found stem subsidence in four asymptomatic patients, which is often the case in this type of prosthesis design [16].…”

Subsidence of titanium straight stems in combination with highly viscous bone cement

“…These results are better than those of a control group with chromium-cobalt stems from the same hospital [25]. However, a 10% rate of osteolysis and a 30% rate of subsidence were also observed [1].…”

“…In a followup note [23], after 10 years, an inferior survival (80.9% versus 98.2%) and a higher rate of subsidence (31% versus 16%) were found for titanium versus chromium-cobalt straight stems. In another institution for the same stem, two loosenings in 126 stems were reported after 9.1 years [1]. These results are better than those of a control group with chromium-cobalt stems from the same hospital [25].…”

“…However, the cementing method seems to be the crucial element. While in the studies by Maurer et al [15] and Schweizer et al [23] a low-viscosity cement was used, Acklin et al [1] and our institution used a high viscosity cement (Refobacin Palacos R). High viscosity bone cements showed more favourable results in larger analyses [5,12].…”

When should joint prostheses be cemented?

“…Dies betrifft sowohl den Schaft als auch die Pfanne, unabhängig von zementierter oder zementfreier Implantation. In groß angelegten Studien wurden in der primären Hüften-doprothetik generelle Lockerungsraten von 4-10% nach 10 Jahren Standzeit beschrieben [1,26]. Im Bestreben, die langlebigste Implantatkombination zu erreichen, sind in den letzten Jahrzehnten eine Vielzahl verschiedener Pfannen-und Schaftdesigns entwickelt worden, aus welchen sich über 20 Kombinationsmöglich-keiten ergeben.…”