title: Small and similar amounts of micromotion in an anatomical stem and a customized cementless femoral stem in regular-shaped femurs. A 5-year follow-up randomized RSA study.
abstract: OBJECTIVE
  High primary stability is important for long-term survival of uncemented femoral stems. Different stem designs are currently in use. The ABG-I is a well-documented anatomical stem with a press-fit design. The Unique stem is designed for a tight customized fit to the cortical bone of the upper femur. This implant was initially developed for patients with abnormal anatomy, but the concept can also be used in patients with normal femoral anatomy. We present 5-year radiostereometric analysis (RSA) results from a randomized study comparing the ABG-I anatomical stem with the Unique femoral stem.
  
  
  METHODS
  100 hips with regular upper femur anatomy were randomized to either the ABG-I stem or the Unique femoral stem. RSA measurements were performed postoperatively and after 3, 6, 12, 24, and 60 months.
  
  
  RESULTS
  RSA measurements from 80 hips were available for analysis at the 5-year follow-up. Small amounts of movement were observed for both stems, with no statistically significant differences between the 2 types.
  
  
  CONCLUSIONS
  No improvement in long-term stability was found from using a customized stem design. However, no patients with abnormal geometry of the upper femur were included in this study.
authors.affiliation: Orthopaedic Research Centre , Department of Orthopaedic Surgery, Trondheim University Hospital.
authors.forename: Mona
authors.initials: M
authors.lastname: Nysted
authors.forename: Olav A
authors.initials: OA
authors.lastname: Foss
authors.forename: Jomar
authors.initials: J
authors.lastname: Klaksvik
authors.forename: Pål
authors.initials: P
authors.lastname: Benum
authors.forename: Kristin
authors.initials: K
authors.lastname: Haugan
authors.forename: Otto Schnell
authors.initials: OS
authors.lastname: Husby
authors.forename: Arild
authors.initials: A
authors.lastname: Aamodt
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D016059:Range of Motion, Articular