title: Retinal arteriolar narrowing and incidence of knee replacement for osteoarthritis: a prospective cohort study.
abstract: OBJECTIVE
  The role of the microcirculation in the pathogenesis of osteoarthritis (OA) remains unclear. This prospective cohort study examined the association between retinal vascular calibre and incidence of knee replacement for OA.
  
  
  METHODS
  1838 participants of the Australian Diabetes, Obesity and Lifestyle (AusDiab) Study had retinal vascular calibre measured using a nonmydriatic digital fundus camera in 1999-2000 and were aged ≥ 40 years at joint replacement data collection commencement. The incidence of knee replacement for OA during 2002-2011 was determined by linking cohort records to the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR).
  
  
  RESULTS
  77 participants underwent knee replacement for OA. They had narrower retinal arteriolar calibre compared with those without knee replacement (166.1 ± 24.8 μm vs 174.3 ± 24.5 μm, P = 0.004). For every one standard deviation reduction in retinal arteriolar calibre, the incidence of knee replacement increased by 25% (HR 1.25, 95% confidence interval (CI) 1.00-1.56). Participants in the narrower two-thirds of arteriolar calibre had twice the risk of knee replacement compared with those in the widest one-third (HR 2.00, 95% CI 1.07-3.74, P = 0.03) after adjustment for sex, body mass index (BMI), physical activity and HbA1c. There was no association for retinal venular calibre.
  
  
  CONCLUSIONS
  Retinal arteriolar narrowing is associated with increased risk of knee replacement for OA suggesting that further work is warranted to determine the role of the microcirculation in the pathogenesis of knee OA.
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia. Electronic address: monira.hussain@monash.edu.
authors.forename: S M
authors.initials: SM
authors.lastname: Hussain
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia. Electronic address: yuanyuan.wang@monash.edu.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Baker IDI Heart and Diabetes Institute, Melbourne, VIC 3004, Australia. Electronic address: jonathan.shaw@bakeridi.edu.au.
authors.forename: J E
authors.initials: JE
authors.lastname: Shaw
authors.affiliation: Baker IDI Heart and Diabetes Institute, Melbourne, VIC 3004, Australia. Electronic address: dianna.magliano@bakeridi.edu.au.
authors.forename: D J
authors.initials: DJ
authors.lastname: Magliano
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Center, Duke-NUS Graduate Medical School, National University of Singapore, Singapore. Electronic address: tien_yin_wong@nuhs.edu.sg.
authors.forename: T Y
authors.initials: TY
authors.lastname: Wong
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia. Electronic address: anita.wluka@monash.edu.
authors.forename: A E
authors.initials: AE
authors.lastname: Wluka
authors.affiliation: Department of Surgery, Flinders University Adelaide, SA, Australia; Australian Orthopaedic Association National Joint Replacement Registry, Discipline of Public Health, School of Population Health & Clinical Practice, University of Adelaide, SA 5005, Australia. Electronic address: segraves@aoanjrr.org.au.
authors.forename: S
authors.initials: S
authors.lastname: Graves
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Australia; Indigenous Eye Health Unit, Melbourne School of Population and Global Health, The University of Melbourne, Australia. Electronic address: robyn.tapp@unimelb.edu.au.
authors.forename: R J
authors.initials: RJ
authors.lastname: Tapp
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, VIC 3004, Australia. Electronic address: flavia.cicuttini@monash.edu.
authors.forename: F M
authors.initials: FM
authors.lastname: Cicuttini
mesh_terms: D000328:Adult; D000368:Aged; D001160:Arterioles / Q000473:pathology*; D019645:Arthroplasty, Replacement, Knee; D001315:Australia; D015331:Cohort Studies; D003251:Constriction, Pathologic / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D019721:Ophthalmoscopes; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery*; D011446:Prospective Studies; D012042:Registries; D012171:Retinal Vessels / Q000473:pathology*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: Knee replacement; Microcirculation; Osteoarthritis; Retinal arteriolar calibre; Retinal venular calibre