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Journal of Bone and Joint Surgery - British Volume, Vol 91-B, Issue 9,
1158-1163.
doi: 10.1302/0301-620X.91B9.22023 Copyright © 2009 by British Editorial Society of Bone and Joint Surgery Fixation and loosening of the cemented Müller straight stemA LONG-TERM CLINICAL AND RADIOLOGICAL REVIEWM. Clauss, MD, Orthopaedic Surgeon1; M. Luem, BSc, Clinical Research Associate1; P. E. Ochsner, MD, Professor, Former Head of Department1; and T. Ilchmann, MD, PhD, Orthopaedic Surgeon11 Department of Orthopaedic Surgery, Kantonsspital Liestal, Rheinstrasse 26, CH 4410, Liestal, Switzerland. Correspondence should be sent to Dr M. Clauss; e-mail: martin.clauss{at}ksli.ch
The original forged Müller straight stem (CoNiCr) has shown excellent ten- to 15-year results. We undertook a long-term survival analysis with special emphasis on radiological changes within a 20-year period of follow-up. In all, 165 primary total hip replacements, undertaken between July 1984 and June 1987 were followed prospectively. Clinical follow-up included a standardised clinical examination, and radiological assessment was based on a standardised anteroposterior radiograph of the pelvis, which was studied for the presence of osteolysis, debonding and cortical atrophy. Survival of the stem with revision for any reason was 81% (95% confidence interval (CI), 76 to 86) at 20 years and for aseptic loosening 87% (95% CI, 82 to 90). At the 20-year follow-up, 15 of the surviving 36 stems showed no radiological changes. Debonding (p = 0.005), osteolysis (p = 0.003) and linear polyethylene wear (p = 0.016) were associated with aseptic loosening, whereas cortical atrophy was not associated with failure (p = 0.008). The 20-year results of the Müller straight stem are comparable to those of other successful cemented systems with similar follow-up. Radiological changes are frequently observed, but with a low incidence of progression, and rarely result in revision. Cortical atrophy appears to be an effect of ageing and not a sign of loosening of the femoral component.
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