• D A Räber, S Czaja, and E W Morscher.
• Department of Orthopaedic Surgery, University of Basel, Switzerland.
• Arch Orthop Trauma Surg. 2001 Jan 1; 121 (1-2): 38-42.

AbstractBetween September 1980 and May 1982, 112 primary unilateral total hip arthroplasties with the original cemented M. E. Müller Straight stem (manufactured from Protasul-10, a CoCrNiMo alloy) were inserted in 109 consecutive patients, all combined with non-cemented, non-coated polyethylene RM cups. Forty-three patients (40%) died during the follow-up period, all with the implant in place. Of the 66 surviving patients, 2 (1.8%) were lost to follow-up, and 7 (6.3%) were unable to attend the 15-year clinical and radiological follow-up. Eight stems (7.3%) had to be revised for aseptic loosening and 3 stems (2.7%), for septic loosening. The 15-year survivorship of the Müller Straight stem regarding aseptic loosening is, therefore, 92.7%. Forty-six patients with 49 total hip replacements could be evaluated clinically and radiologically after 15 years. The mean duration of clinical follow-up for these 46 patients (42.2%) was 14.8 years (range 12.8-16.5 years). There were 22 women (48%) and 24 men (52%). The mean age at the time of the operation was 62 years (range 38-80 years), and 78 years (range 59-93 years) at the time of the latest follow-up. The mean Harris Hip Score at the latest follow-up evaluation of the 49 hip joints was 85 points (range 34-100 points). Of the 46 patients, 39 (85%) had a good or excellent clinical result. Radiographic follow-up was performed for 49 hips: 35 (70%) had linear or focal osteolysis in one or more zones of the stem, but only 4 (8%) had evidence of definitive loosening (linear radiolucency of over 2 mm all around the stem). Subsidence of over 2 mm was found in 20 hips (41%), 6 of them within the cement mantle. There was no correlation between subsidence and pain. The cause for the poor results is primarily the high rate of aseptic loosening of the non-coated, non-cemented all-polyethylene RM cups, with a loosening rate of 63% and a revision rate of 25% after 15 years.

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