Prospective clinical and radiostereometric analysis of the Fitmore short-stem total hip arthroplasty
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Uncemented short, curved femoral stems may help save proximal bone stock during total hip arthroplasty (THA) and facilitate insertion in minimal invasive surgery. The aim of this 2 year, prospective, single-center study was to examine the stability and migration of the Fitmore ® stem in THA using model-based radiostereometric analysis (RSA), and thus predict the implant’s long-term survival. In addition, we evaluated the stem’s clinical performance using standard clinical measures.
Patients and methods
We conducted a prospective cohort study of 34 THA patients who received the short Fitmore Hip Stem (Zimmer, Winterthur, Switzerland). At 3, 6, 12 and 24 months postoperatively, the patients underwent clinical evaluation and radiostereometric analysis (RSA) to measure stem migration.
RSA analysis revealed a mean subsidence of −0.39 mm (95 % CI −0.60 to −0.18) at 3 months with no further migration after 2 years. Mean internal rotation along the longitudinal axis was 1.09° (95 % CI 0.52–1.66) at 2 years, versus 0.85° (95 % CI 0.44–1.26) at 3 months. The Harris hip score improved from 60 (range 30–80) preoperatively to 99 (range 83–100) after 2 years. Three patients underwent revision due to deep infection, non-specific thigh pain and aseptic loosening in one case.
We conclude that the Fitmore Hip Stem stabilizes after 3 months and achieves good short-term clinical results in most cases.
KeywordsRSA Fitmore Stem migration Short stem
We thank Bart Kaptein and Lennard Koster for the RSA analysis and for technical support, and Tina Stölzle for general study support.
Compliance with ethical standards
Conflicts of interest
The authors declare that they have no conflict of interest.
This study received financial support for statistic and RSA analysis from Zimmer GmbH.
- 9.Freitag T, Hein MA, Wernerus D et al. (2015) Bone remodelling after femoral short stem implantation in total hip arthroplasty: 1-year results from a randomized DEXA study. Arch orthop trauma surg [Epub ahead of print]Google Scholar
- 14.Harris WH (1969) Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg (Am) 51:737–755Google Scholar
- 34.Wolf O, Mattsson P, Milbrink J et al (2010) Periprosthetic bone mineral density and fixation of the uncemented CLS stem related to different weight bearing regimes: a randomized study using DXA and RSA in 38 patients followed for 5 years. Acta Orthop 81:286–291PubMedCentralCrossRefPubMedGoogle Scholar