Work that involved jolting of the feet and legs more than doubled the risk of knee osteoarthritis (OA) among men while stair climbing increased the risk for the disorder by over 50 percent according to a recently published study involving a cross-sectional analysis of Florida subjects. The study also showed a strong relationship between work-related stair climbing and foot OA among males.
For females, a significant association was found between standing on a rigid surface for two or more hours a day and knee OA. Also, jolting of the hands and legs nearly doubled the likelihood of experiencing hand OA among females.
Squatting had little relationship with the risk of knee OA among either men or women. No relationship was found for cervical and hand OA among both genders for the work activities assessed by the study questionnaire.
The study sample included 3,548 subjects — 1,098 males and 2,450 females – chosen in a nonrandom manner in the Clearwater, Florida area.
The Bottom Line – How This Applies To Ergonomists
This study raises the concern for a frequently overlooked work activity – jolting motions through the lower extremity. Among men, it creates a much higher risk than stair climbing for knee OA.
Also, work exposures associated with the risk of OA were different depending on gender. Women are more likely to experience knee OA from standing on a rigid surface as opposed to men who demonstrated greater risk from jolting of the feet and legs. Men experienced a higher risk of foot OA from stair climbing than women.
More specific work exposures need to be identified to determine any work relatedness between job tasks and both hand and cervical OA.
Other Key Study Points
Age was associated with knee, foot, hand, and cervical spine OA for both men and women. BMI had an impact on the risk for knee, foot, hand, and cervical spine OA among women and the risk for knee and foot OA for men.
For all subjects, radiographic OA had a prevalence of
- 17% at the knee
- 20% at the foot
- 42% at the hand
- 30% at the cervical spine
The authors conceded that they could not control for genetic predisposition. Hence, the reported OA incidence may be overestimated. Also, study outcomes may have been influenced by the healthy worker effect.
The mean age was 63.4 years for men and 61.4 years for women. The BMI was 27.6 and 26.2 kg/m2 for men and women, respectively.
Research subjects were individuals participating in the Clearwater Osteoarthritis Study, an ongoing, 40 year-old, longitudinal, cohort analysis of the risk factors related to the cause and progression of radiographic OA.
- A physical exam
- Radiographic evaluation of the knee, hand , foot, and cervical spine
- A questionnaire that included inquires relative to work tasks such as:
- stair climbing (> 5 times/day)
- standing on a rigid surface (≥2 hours/day)
- jolting of the feet/legs
- jolting of the hands/legs
Age and body mass index were taken into consideration as confounders. The study excluded those with rheumatoid arthritis, gout, disabling neuralgic disease and individuals confined to a wheel chair.
Once radiographic findings were identified, comparison between exposure groups was made. For example, the radiographic findings of those who reported a yes to “jolting of the feet and legs” were compared to those who said yes to “sitting most of the time”.
This study can be acquired at:
Article Title: Job-Related Osteoarthritis of the Knee, Foot, Hand, and Cervical Spine
Publication: Journal of Occupational and Environmental Medicine, 52:33-38, 2010
Authors: T E Bernard, F V Wilder, M Aluoch, and P E Leaverton
This article originally appeared in The Ergonomics Report™ on 2010-02-01.