title: The effect of middle-age body weight and physical activity on the risk of early revision hip arthroplasty: a cohort study of 1,535 individuals.
abstract: BACKGROUND
  Overweight and a high level of physical activity are known risk factors for loosening of a total hip arthroplasty (THA) due to primary osteoarthritis. We wanted to investigate how these factors, together with age and sex, affect the risk of revision surgery.
  
  
  METHODS
  We matched data from the Norwegian Arthroplasty Register with information on risk factors collected at a cardiovascular screening. We identified 1,535 primary THAs in the screened cohort (930 cemented implants using well-documented cement). Of the participants included, 969 were female. Mean age at screening was 49 years, at primary THA 63 years, and 69 years at the end of follow-up. We used Cox regression analysis to estimate relative risks (RRs). Event was defined as implant revision due to aseptic loosening of cup, stem or both. Follow-up was time from primary THA to event or censoring.
  
  
  RESULTS
  Men were at greater risk than women of loosening of the femoral stem (RR 2.0, 95% CI 1.3-3.2). Both men and women with upper-quartile body weight were at increased risk of revision due to loosening of the stem (RR 2.5 and 2.7, respectively). Men with a high level of physical activity during leisure time were at increased risk of revision due to loosening of the cup (RR 4.8, 95% CI 1.3-18). In the multivariate model with adjustment for activity, there was little association between age at primary THA and risk of revision due to loosening.
  
  
  CONCLUSIONS
  We found that body weight and physical activity recorded long before THA affected the survival of total hip arthroplasties. Controlling for these variables weakened the association between age at primary surgery and aseptic loosening. Men had an increased risk of loosening of the femoral stem, also after controlling for lifestyle factors.
authors: Orthopaedic Centre, Ullevål University Hospital, Oslo NO-0407, Norway. Gunnar.Flugsrud@ioks.uio.no
authors: Gunnar B
authors: GB
authors: Flugsrud
authors: Lars
authors: L
authors: Nordsletten
authors: Birgitte
authors: B
authors: Espehaug
authors: Leif I
authors: LI
authors: Havelin
authors: Haakon E
authors: HE
authors: Meyer
mesh_terms: D000367:Age Factors; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight; D011474:Prosthesis Design; D016459:Prosthesis-Related Infections / Q000209:etiology; D012086:Reoperation; D012307:Risk Factors; D012737:Sex Factors