title: Risk factors for lesions of the knee menisci among workers in South Korea's national parks.
abstract: BACKGROUND
  This study was designed to investigate the prevalence of the menisci lesions in national park workers and work factors affecting this prevalence.
  
  
  METHODS
  The study subjects were 698 workers who worked in 20 Korean national parks in 2014. An orthopedist visited each national park and performed physical examinations. Knee MRI was performed if the McMurray test or Apley test was positive and there was a complaint of pain in knee area. An orthopedist and a radiologist respectively read these images of the menisci using a grading system based on the MRI signals. To calculate the cumulative intensity of trekking of the workers, the mean trail distance, the difficulty of the trail, the tenure at each national parks, and the number of treks per month for each worker from the start of work until the present were investigated. Chi-square tests was performed to see if there were differences in the menisci lesions grade according to the variables. The variables used in the Chi-square test were evaluated using simple logistic regression analysis to get crude odds ratios, and adjusted odds ratios and 95 % confidence intervals were calculated using multivariate logistic regression analysis after establishing three different models according to the adjusted variables.
  
  
  RESULTS
  According to the MRI signal grades of menisci, 29 % were grade 0, 11.3 % were grade 1, 46.0 % were grade 2, and 13.7 % were grade 3. The differences in the MRI signal grades of menisci according to age and the intensity of trekking as calculated by the three different methods were statistically significant. Multiple logistic regression analysis was performed for three models. In model 1, there was no statistically significant factor affecting the menisci lesions. In model 2, among the factors affecting the menisci lesions, the OR of a high cumulative intensity of trekking was 4.08 (95 % CI 1.00-16.61), and in model 3, the OR of a high cumulative intensity of trekking was 5.84 (95 % CI 1.09-31.26).
  
  
  CONCLUSIONS
  The factor that most affected the menisci lesions among the workers in Korean national park was a high cumulative intensity of trekking.
authors.affiliation: Department of Occupational and Environmental Medicine, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Donghee
authors.initials: D
authors.lastname: Shin
authors.affiliation: Department of Occupational and Environmental Medicine, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Kanwoo
authors.initials: K
authors.lastname: Youn
authors.affiliation: Department of Radiology, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Eunja
authors.initials: E
authors.lastname: Lee
authors.affiliation: Department of Occupational and Environmental Medicine, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Myeongjun
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Occupational and Environmental Medicine, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Hweemin
authors.initials: H
authors.lastname: Chung
authors.affiliation: Department of Orthopedics, Wonjin Green Hospital, 568-1 Sagajeong-ro 49-gil 53, Jungrang-gu, Seoul South Korea.
authors.forename: Deokweon
authors.initials: D
authors.lastname: Kim
keywords: Knee; MRI; Menisci lesions; National park workers; Trekking