title: Predicting OA progression to total hip replacement: can we do better than risk factors alone using active shape modelling as an imaging biomarker?
abstract: OBJECTIVE
  Previously, active shape modelling (ASM) of the proximal femur was shown to identify those individuals at highest risk of developing radiographic OA. Here we determine whether ASM predicts the need for total hip replacement (THR) independent of Kellgren-Lawrence grade (KLG) and other known risk factors.
  
  
  METHODS
  A retrospective cohort study of 141 subjects consulting primary care with new hip pain was conducted. Pelvic radiographs taken on recruitment were assessed for KLG, centre-edge angle, acetabular depth and femoral head migration. Clinical factors (duration of pain, use of a stick and physical function) were collected by self-completed questionnaires. ASM differences between shape mode scores at baseline for individuals who underwent THR during the 5-year follow-up (n = 27) and those whose OA did not progress radiographically (n = 75) were compared.
  
  
  RESULTS
  A 1 s.d. reduction in baseline ASM mode 2 score was associated with an 81% reduction in odds of THR (OR = 0.19, 95% CI 0.52, 0.70) after adjustment for KLG, radiographic and clinical factors. A similar reduction in odds of THR was associated with a 1 s.d. reduction in mode 3 (OR = 0.45, 95% CI 0.28, 0.71) and a 1 s.d. increase in mode 4 score (OR = 2.8, 95% CI 1.7, 4.7), although these associations were no longer significant after adjustment for KLG and clinical factors.
  
  
  CONCLUSIONS
  ASM of the hip joint is a reliable early biomarker of radiographic OA severity, which can improve the ability to identify patients at higher risk of rapid progression and poor outcome even when KLG and clinical risk factors are taken into account.
authors.affiliation: Bone and Musculoskeletal Research Programme, Aberdeen, UK. r.j.barr@abdn.ac.uk
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Barr
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Gregory
authors.forename: David M
authors.initials: DM
authors.lastname: Reid
authors.forename: Richard M
authors.initials: RM
authors.lastname: Aspden
authors.forename: Kanako
authors.initials: K
authors.lastname: Yoshida
authors.forename: Gillian
authors.initials: G
authors.lastname: Hosie
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Silman
authors.forename: Salvatore
authors.initials: S
authors.lastname: Alesci
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Macfarlane
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000473:pathology*; D000368:Aged; D018771:Arthralgia; D019644:Arthroplasty, Replacement, Hip; D015415:Biomarkers; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D011237:Predictive Value of Tests; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers