Abstract
Introduction: The cemented MS-30 stem (Morscher-Spotorno) has been introduced with a matte surface in clinical practice in 1990. Since it has been shown that tappered collarless stems with a polished surface show better results than those with a matte surface , the MS-30 stem was also manufactured in a polished version from 1994 on. Because no prospective study comparing the two surfaces was published until then and our own results with this stem with a matte surface revealed excellent results with no revision and no osteolysis during a 4 year period, we decided to perform such a study including 125 implants in each group. The only variable was the characteristics of the surface.
Patients and Methods: In the first group with a matte surface there are 61 men with a mean age of 65 (41–86) years and 66 women with 73 (54–89) years. In the second group there are 63 men with a mean age of 64 (35–88) years, and 65 women with 70 (40–91) years. In 21 patients, the MS-30 stem was inserted bilaterally during the index period. All patients were followed up for a minimum of 8 years. The average observation time was 8.6 (8.0–10.3) years. No patients were lost to the follow-up. Ninety-two MS-30 stems with a matte and 103 with a polished surface had a minimum 8-year clinical and radiological check. As an acetabular component the Press-Fit Cup was used.
Results: The overall results were excellent and good in the group with the matte surface in 92% and in 91% with a polished surface. Two revisions each had to be done for aseptic loosening Two hips had to be revised for recurrent early dislocation. The overall revision rate is thus 6/255 (2.4%), and 4/244 (1.5%) for aseptic loosening. Six osteolyses (one confluent) in the group with the matte suface and 7 in the group of polished stems were detected. Subsidence of 2–5mm occured in 10 cases each. There was no osteolysis and no revision for aseptic loosening, however, two revisions for dislocation for the Morscher Press-Fit Cup.
Conclusion: No significant difference in the outcome of MS-30 stems in each group could be found during a 8–10-year observation period. The main reason for the almost equally excellent performance may be the design of the centralizer, which resists both a debonding of the stem from the cement and subsequent subsidence as a precondition for fretting between the two surfaces at the metal/cement interface. Another reason is the cement and the good cement mantle which influence the final result of a cemented THR more than the design of the implant, as it is shown by the Swedish and Norwegian implant register.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
