Purpose: The use of cementless prosthesis has increased in the last 30 years with the aim of improving the long-term results of total hip arthroplasties in young and active patients. Encouraging results have recently been reported for cementless titanium and cobalt chromium stems. However, there are few studies with long-term follow-up, and the majority have analysed several models of uncemented stems due to their modifications over the years. Therefore, the aim was to assess the long-term survival rate of the Mittelmeier Mark III or Autophor 900-S stem.
Methods: A retrospective cohort study of both gender patients under 70 years old with at least one implanted Mittelmeier Mark III uncemented stem was performed. Survival rate was defined as the proportion of stems that did not need a surgical revision from any cause. Clinical status was evaluated using the Merle d'Aubigne scale modified by Matta (excellent/good/fair/poor).
Results: Between 1990 and 1999, 73 stems were implanted. The mean (SD) age at surgical time was 49.3 (9.9) years, and the median (range) of follow-up was 22 (1-28) years. The overall survival rate was 93% (68/73, 95%CI: 85-97%). The stem revisions were due to stem breakage (n = 2), to aseptic loosening (n = 2) and to septic loosening (n = 1). Clinical results were: excellent 84%, good 15% and fair 1.5%.
Conclusions: The Mittelmeier Mark III stem had an excellent survival rate with a stable long-term fixation and excellent clinical outcomes.
Keywords: Autophor 900-S; Fully porous-coated uncemented stem; Long-term follow-up; Mittelmeier Mark III; Stem survival; Total hip arthroplasty.
© 2021. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.