title: Total hip replacement but not clinical osteoarthritis can be predicted by the shape of the hip: a prospective cohort study (CHECK).
abstract: OBJECTIVE
  To investigate the association between baseline hip shape and both clinical hip osteoarthritis (OA) and total hip replacement (THR) at 5-year follow-up.
  
  
  METHODS
  Individuals from the Cohort Hip and Cohort Knee (CHECK) study, with early symptomatic OA, having standardized anteroposterior pelvic radiographs at baseline and 5-year follow-up (n = 723) were included. Hip shape on the radiographs was assessed using statistical shape modeling (SSM). Hips fulfilling the American College of Rheumatology (ACR) criteria at follow-up were classified as clinical OA. The association between each mode of shape variation and both outcome measures was calculated by Generalized Estimating Equations (GEE).
  
  
  RESULTS
  The included individuals comprised 575 females and 148 males (mean age 55.9 ± 5.2 years). At baseline, 8% fulfilled the ACR criteria, 76% had no radiographic hip OA [Kellgren & Lawrence (K&L) = 0] and 24% had doubtful OA (K&L = 1). At follow-up, 147 hips (10.4%) fulfilled the ACR criteria and 35 hips (2.5%) had received THR. Five shape variants (modes) at baseline associated significantly with THR within 5 years. When combined in one GEE model, these shape variants resulted in a predictive power indicated by an area under the curve of 0.81. No shape variants associated with the presence of clinical OA at follow-up.
  
  
  CONCLUSIONS
  The shape of the hip as quantified by an SSM has a good predictive value for THR, whereas variation in shape cannot predict clinical OA. Minor shape variants may be used as a radiographic biomarker to predict the future risk of THR.
authors: Department of Orthopaedics, Erasmus MC University Medical Centre, Rotterdam, The Netherlands. r.agricola@erasmusmc.nl
authors: R
authors: R
authors: Agricola
authors: M
authors: M
authors: Reijman
authors: S M A
authors: SM
authors: Bierma-Zeinstra
authors: J A N
authors: JA
authors: Verhaar
authors: H
authors: H
authors: Weinans
authors: J H
authors: JH
authors: Waarsing
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000473:pathology; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors