title: Prospective clinical and radiostereometric analysis of the Fitmore short-stem total hip arthroplasty.
abstract: BACKGROUND
  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.
  
  
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  We conclude that the Fitmore Hip Stem stabilizes after 3 months and achieves good short-term clinical results in most cases.
authors.affiliation: Orthopedic Surgery, Kantonsspital Graubünden, Loestrasse 99, 7000, Chur, Switzerland. yvespascal.acklin@gmail.com.
authors.forename: Yves P
authors.initials: YP
authors.lastname: Acklin
authors.affiliation: Orthopedic Surgery, Kantonsspital Graubünden, Loestrasse 99, 7000, Chur, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Jenni
authors.affiliation: Orthopedic Surgery, Kantonsspital Graubünden, Loestrasse 99, 7000, Chur, Switzerland.
authors.forename: Heinz
authors.initials: H
authors.lastname: Bereiter
authors.affiliation: Orthopedic Surgery, Kantonsspital Graubünden, Loestrasse 99, 7000, Chur, Switzerland.
authors.forename: Caroline
authors.initials: C
authors.lastname: Thalmann
authors.affiliation: Orthopedic Surgery, Kantonsspital Baselland, Rheinstrasse 26, Liestal, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Stoffel
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D015331:Cohort Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D011474:Prosthesis Design; D059869:Radiostereometric Analysis; D055815:Young Adult
keywords: Fitmore; RSA; Short stem; Stem migration