title: Does moderate or severe nonspecific knee injury affect radiographic osteoarthritis incidence and progression?
abstract: BACKGROUND
  Knee injuries can lead to radiographic osteoarthritis (ROA). Injuries may be "specific" (SI) including ligament or meniscal tears or patellar trauma, or "nonspecific" (NSI). Our objective is to understand the effect of knee NSI on ROA incidence and progression.
  
  
  METHODS
  163 people (sample-weighted for population representativeness) aged 40+ with history of knee pain had radiographs assessed on Kellgren Lawrence (KL) grade (0/1 collapsed) at baseline and follow-up (median 3.2 years apart). Progression was an increase in KL score. SIs and NSIs were labeled "severe" (walking aid for ≥1 week) or "moderate". One model treated SI and NSI as dichotomous (yes/no), and another as trichotomous (none/moderate/severe). Models were adjusted for age, sex, BMI, KL grade and follow-up time.
  
  
  RESULTS
  SI/NSI history was none, moderate (7.8/24.4%) or severe (11.0/10.8%). Duration at baseline since SI/NSI ranged from <1 year to several decades (SI/NSI mean 4.6/6.5 years). SI was significantly associated with ROA incidence and progression (odds ratio (OR) = 2.90; 95% CI = 1.04, 8.09), but NSI showed no significant effect (OR = 1.36; 95% CI = 0.61, 3.02). In the trichotomous model, severe SI was significant (OR = 4.35, 95% CI = 1.26, 15.02), while moderate SI was not (OR = 1.51, 95% CI = 0.33, 6.84). NSI showed no effect: moderate OR = 1.51, 95% CI = 0.61, 3.74; severe OR = 0.90, 95% CI = 0.24, 3.40. This study had 80% power to detect an NSI OR of 2.9.
  
  
  CONCLUSIONS
  We find no evidence that history of NSI affects knee ROA incidence and progression in a population with knee pain, adjusting for SI, age, sex, BMI, KL grade and follow-up time.
authors.affiliation: Arthritis Research Centre of Canada, 5591 No, 3 Rd, Richmond, BC, V6X 2C7, Canada. esayre@arthritisresearch.ca.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Sayre
authors.forename: Joel
authors.initials: J
authors.lastname: Singer
authors.forename: Anona
authors.initials: A
authors.lastname: Thorne
authors.forename: Hubert
authors.initials: H
authors.lastname: Wong
authors.forename: Jacek A
authors.initials: JA
authors.lastname: Kopec
authors.forename: John M
authors.initials: JM
authors.lastname: Esdaile
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
authors.forename: Savvas
authors.initials: S
authors.lastname: Nicolaou
authors.forename: Jolanda
authors.initials: J
authors.lastname: Cibere
mesh_terms: D000368:Aged; D001955:British Columbia / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000150:complications*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000453:epidemiology* / Q000209:etiology