Wrist district as a target for biomechanical risk in milking parlor workers: an emerging occupational risk?

Objective Dairy parlours activities expose workers to biomechanical risk: repetitive movements and awkward postures of the hand and wrist may heighten the risk of carpal tunnel syndrome. Median nerve impairment can be investigated with ultrasonography and through nerve conduction studies. Since this approach is not feasible on a large scale, the development of other screening tools are needed to be used in the periodical health surveillance of dairy workers. Methods Forty milking male parlours workers in the Region of Lombardy for almost three years were selected. The study protocol included: 1) identification of worker’s symptoms through the administration of a questionnaire, 2) ultrasound imaging of the carpal tunnel inlet (portable ultrasound device)3) nerve conduction studies (NCS). Descriptive statistics analysis and univariate analysis were performed with statistical package SAS. Results The anamnestic questionnaire, considered positive if at least one symptom was present maximum two weeks before the examination, showed a high level of specificity (83, 3%) and sensibility (80%) if compared with electromyography results. The specificity of the questionnaire raises at 100% if 2 or more symptoms were present. Ultrasound results showed a prevalence of median nerve sufferance (median nerve area major than 0.1cm2) of 55%. However, we didn’t find a statistical correlation between US and nerve conduction studies (NCS). Conclusions This prototype questionnaire proved to be predictive of early stage carpal tunnel syndrome and may be adequate for the periodical screening of dairy parlor workers. The use of ultrasound needs to be improved and its association with electromiography may be advisable. It is interesting to note the relative high prevalence of wrist disorders found in dairy parlour workers, that is somehow unexpected considering the recent improvement of milking routine through machineries.