title: Knee pain, knee osteoarthritis, and the risk of fracture.
abstract: OBJECTIVE
  Patients with osteoarthritis (OA) have increased bone mineral density; however, the association between knee OA and fracture is controversial. Few data exist on the association between knee pain and fracture. We examined the association of knee OA and knee pain with fracture and falls in elderly men and women.
  
  
  METHODS
  The study group comprised 6,641 men and women ages > or =75 years who participated in a 3-year randomized controlled trial of intramuscular vitamin D therapy. Patients completed a questionnaire about knee pain and OA. Fracture and fall data were collected prospectively every 6 months.
  
  
  RESULTS
  Knee pain prevalence and a clinician diagnosis of knee OA were 35.2% and 6.8%, respectively. A total of 436 incident nonvertebral fractures were reported, and 3,992 patients sustained a fall. Prevalent knee pain was associated with an increased risk of falls (hazard ratio [HR] 1.26, 95% confidence interval [95% CI] 1.17-1.36) and hip fracture (HR 2.0, 95% CI 1.18-3.37). Increasing severity of knee pain was associated with a greater risk of falls and hip fracture. Clinician diagnosis of knee OA was associated with an increased risk of nonvertebral fractures (HR 1.61, 95% CI 1.09-2.36). The increased risk of fracture was not substantially reduced by adjusting for falls, but was attenuated by adjustment for the use of walking aids.
  
  
  CONCLUSIONS
  Patients with a clinical diagnosis of knee OA and with knee pain have an increased risk of nonvertebral and hip fracture. This is not explained by the increased risk of falls, but is more likely to be due to the severity of falls sustained. Knee pain and OA should be regarded as independent risk factors for fracture.
authors.affiliation: MRC Epidemiology Resource Centre, University of Southampton, Southampton, United Kingdom. nka@mrc.soton.ac.uk
authors.forename: Nigel K
authors.initials: NK
authors.lastname: Arden
authors.forename: Sarah
authors.initials: S
authors.lastname: Crozier
authors.forename: Helen
authors.initials: H
authors.lastname: Smith
authors.forename: Frazer
authors.initials: F
authors.lastname: Anderson
authors.forename: Christopher
authors.initials: C
authors.lastname: Edwards
authors.forename: Helen
authors.initials: H
authors.lastname: Raphael
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004311:Double-Blind Method; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000517:prevention & control; D006620:Hip Fractures / Q000453:epidemiology; D006801:Humans; D007273:Injections, Intramuscular; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D010003:Osteoarthritis / Q000150:complications* / Q000188:drug therapy / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D010919:Placebos; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000008:administration & dosage / Q000627:therapeutic use*; D016138:Walking
chemical_list: D010919:Placebos; D014807:Vitamin D