Predicting the onset of knee pain: results from a 2-year prospective study of new workers.

OBJECTIVE: To determine the relative contribution of work-related mechanical (injury) factors and psychosocial factors to the onset of a new episode of knee pain, in a cohort of newly employed workers. METHODS: A prospective cohort study of newly employed workers from 12 diverse occupational settings in England (The New Workers Study). 859 newly employed workers, free of knee pain, were identified. Information about occupational mechanical factors (manual handling and postural activities), the occupational physical environment, and psychological and psychosocial factors was collected by self-completion questionnaires. Participants were followed up after 12 and 24 months to identify cases of knee pain onset. Generalised estimating equations were used to estimate the risk of new-onset knee pain, with respect to the exposures previously measured. RESULTS: In total, over the 2-year follow-up period, 108 cases of new-onset knee pain were observed. Mechanical load, postural factors, psychological distress and work-place psychosocial factors all influenced the risk of new-onset knee pain over the 2-year follow-up period. On multivariate analysis, two factors remained independently predictive of knee pain onset: lifting or carrying heavy weights in one hand, and the level of general psychological distress. CONCLUSION: In addition to mechanical (injury) factors, psychological factors are important risk factors for knee pain onset as shown in a population of young newly employed workers.

Predicting the onset of forearm pain: a prospective study across 12 occupational groups.

OBJECTIVE: To determine, among workers free of forearm pain, the role of mechanical and psychosocial factors in predicting future onset. METHODS: A prospective cohort study was conducted among 782 newly employed workers from 12 occupational groups. At baseline, a cohort of 782 workers free of forearm pain was identified and measurement was made about physical and psychosocial aspects of their job and working environment. Subjects were recontacted after 1 year to determine new onsets of forearm pain. A sample of those reporting new onset forearm pain underwent a structured examination of the upper limb. RESULTS: One year after baseline, 666 (85%) subjects were followed up. The overall prevalence of new onset forearm pain was 8.3% (n = 55). The strongest mechanical risk factor was frequent repetitive movements of the arm or wrist (odds ratio [OR] 2.9, 95% confidence interval [95% CI] 1.6-5.2). The strongest psychosocial risk factors were work considered monotonous at least half of the time (OR 3.0, 95% CI 1.6-5.7) or work with little autonomy (OR 2.6, 95% CI 1.1-6.1). Three specific independent risk factors (monotonous work, repetitive wrist movement, working with hands above shoulder level) could distinguish groups of subjects at substantially different risks of onset. CONCLUSIONS: Along with repetitive movements of the arms and wrists, mechanical postural factors and psychosocial factors also are important risk factors for onset of forearm pain. Our study emphasizes the multifactorial nature of risks for onset of forearm pain, and provides leads as to possible mechanisms for prevention.