title: The effects of different weight-bearing regimes on press-fit cup stability: a randomised study with five years of follow-up using radiostereometry.
abstract: OBJECTIVE
  There is little evidence to support immediate weight bearing after uncemented total hip arthroplasty (THA).
  
  
  METHODS
  Thirty-seven patients with unilateral osteoarthritis of the hip received a press-fit cup. Cup stability was assessed with radiostereometry (RSA) over five years. Patients were randomised to immediate full weight bearing, or partial weight bearing for three months.
  
  
  RESULTS
  At five years, we found no difference in micro-motion as assessed with radiostereometry. Numerically, there was more proximal translation and increased inclination with immediate weight bearing, but these values barely exceeded the precision limit for the method. Pooled data for the two groups revealed translations of 0.1-0.3 mm and rotations of 0.2-0.3° over the five year follow-up period.
  
  
  CONCLUSIONS
  We found no adverse effects of immediate weight bearing after THA in relation to stability of these press-fit cups. Early mobilisation might have other advantages.
authors.affiliation: Surgical Sciences, Orthopaedic, Uppsala, Sweden, olof.wolf@akademiska.se
authors.forename: Olof
authors.initials: O
authors.lastname: Wolf
authors.forename: Per
authors.initials: P
authors.lastname: Mattsson
authors.forename: Jan
authors.initials: J
authors.lastname: Milbrink
authors.forename: Sune
authors.initials: S
authors.lastname: Larsson
authors.forename: Hans
authors.initials: H
authors.lastname: Mallmin
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods* / Q000534:rehabilitation; D002484:Cementation; D004434:Early Ambulation; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D013314:Stress, Mechanical; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology