title: A prospective study on knee pain and its risk factors.
abstract: OBJECTIVE
  To evaluate the effects of work-related and individual factors as well as physical activity and sports on the incidence and persistence of knee pain among a working population.
  
  
  METHODS
  Employees of a large Finnish forestry company replied to a questionnaire (a modified version of the Nordic Questionnaire) on musculoskeletal pain and its possible risk factors at the baseline of this study. A cohort of 2122 workers free of knee pain and another cohort of 333 workers with severe knee pain were followed up for one year. The effects of the risk factors on the incidence and persistence of knee pain were studied using multivariable logistic regression models.
  
  
  RESULTS
  A total of 214 (10%) workers developed knee pain during the follow-up. Significant predictors of incident knee pain in the multivariable model were higher age, overweight, smoking, and previous knee injuries. Also, working with the trunk forward flexed in kneeling or standing position and physically strenuous work were non-significant predictors of incident knee pain. Of those 333 workers with severe knee pain at baseline, 220 (66%) still reported severe knee pain after one year. Higher age and job dissatisfaction increased the risk of persistent symptoms. General physical exercise and different sports activities did not predict the incidence or persistence of knee pain.
  
  
  CONCLUSIONS
  In this large prospective study, the risk factors for self-reported knee pain seemed to be highly similar to the risk factors for knee osteoarthritis (OA) reported in other papers. Age, previous knee injuries, overweight, and knee-straining work were those risk factors, which contributed to the incidence of knee pain. Psychosocial elements of work were more involved in the persistence of the symptoms in the knee.
authors.affiliation: Musculoskeletal Research Unit, Department of Physiology, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, FIN-00250 Helsinki, Finland. helena.miranda@occuphealth.fi
authors.forename: H
authors.initials: H
authors.lastname: Miranda
authors.forename: E
authors.initials: E
authors.lastname: Viikari-Juntura
authors.forename: R
authors.initials: R
authors.lastname: Martikainen
authors.forename: H
authors.initials: H
authors.lastname: Riihimäki
mesh_terms: D000328:Adult; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D010146:Pain / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D013177:Sports