Exposure criteria for evaluating lumbar spine load.

OBJECTIVE: As a part of regular revision of the List of Occupational Diseases in the Czech Republic, efforts have been made to add a new item so that lumbar spine disease caused by overload may be recognized as occupational one, with adherence to the valid national rules, that is, clinical criteria are met and objective assessment confirms working conditions under which, according to recent scientific knowledge, such an occupational disease develops. The aim is to provide information on the use of a proposed method for working condition assessment in a real setting, based on the initial experiences gained from a pilot study carried out to validate the method. METHODS: Working conditions were assessed in 55 individuals with chronic low back pain (25 males, 30 females; mean age 45.6 years; mean length of employment 15.6 years). The assessment was based on estimating compressive force on the L4/L5 intervertebral disc when performing potentially high-risk work tasks which were entered into four types of checklists throughout their work shifts. The compression values were calculated using a special module that was developed. RESULTS: In 24 cases comprehensive assessment of all tasks performed showed fulfillment of the proposed criteria of working conditions needed for recognition of occupational disease. Those included healthcare, foundry and forest workers, production operators, cabinetmakers, locksmiths, bricklayers, etc. In all the cases, lumbar spine overload was associated with work tasks requiring combinations of manual handling of objects and trunk rotation or bending. The criteria were not met in 31 subjects. The mean length of employment was 15.4 and 15.8 years in patients who met and did not meet the proposed criteria, respectively. CONCLUSION: The proposed method proved to be applicable in occupational hygiene evaluation in a real setting.

Evaluation of Lumbar Spine Load by Computational Method in Order to Acknowledge Low-back Disorders as Occupational Diseases.

AIM: The aim of the study was to develop a computational module for the prediction of compressive force on the L4/L5 disc suitable for use in field settings. METHOD: The value of compressive force is intended to be used as a proxy measure of the mechanical burden of low-back when performing work activities. The compressive force predicted by the module in a particular worker should be compared with the NIOSH limit value of 3,400 N for the assessment of lumbar spine load during manual lifting tasks. Exceeding the limit will be considered as the fulfilment of "hygienic criterion" that should be met to acknowledge low-back disorder as an occupational disease. To develop the computational module we used the ergonomic software TECNOMATIX Classic Jack taking into account the anthropometric parameters of a worker and ergonomic parameters of his/her work activity. RESULTS: We calculated compressive forces on the L4/L5 disc in about 1,300 simulated combinations of various factors influencing compressive force. Parameters which turned out to be crucial for the compression of L4/L5 disc were included in the computational algorithm. CONCLUSION: Our study was primarily aimed at the assessment of lumbar disorders as occupational diseases. Moreover, the study can contribute to the recommendation of preventive measures to decrease health risks in occupations associated with the overload of low-back region. The graphic maps generated by the computational module enable a fast and exact analysis of particular job.