Stress placed upon the spinal column during the lifting and carrying of loads - development of a worker-specific measurement system

Status:

completed 05/1998

Aims:

The handling of heavy and unwieldy loads combined with work performed in extreme trunk bending postures leads to severe stresses upon the musculo-skeletal system. Access to reliable, continuous stress recording procedures by which the instantaneous stress situation can be monitored must be provided in order to permit prevention measures of a technical and occupational health nature concerning the lifting and carrying of loads, and also to support investigations into industrial diseases (BK 2108 and BK 2109 - diseases of the lumbar and cervical spine of discogenic origin resulting from long-term lifting or carrying of heavy loads). Conventional visual recording methods such as video recordings, pencil and paper methods, etc. are of extremely limited use. The objective of the project was to develop a worker-specific measuring system for automated monitoring and assessment of essential stress variables at workplaces.

Activities/Methods:

The prototype of a measurement system for automated recording of external stress variables such as trunk posture and the loads handled was developed with the inclusion of three degree theses and a dissertation at the Institute of Applied Physics at the University of Bonn. Different types of sensor were employed for recording of the trunk angle. A special sensor jacket was used to record the measured data on the worker over a full working shift; the data were then immediately available for subsequent computer evaluation. A software application was written for evaluation of the measured data incorporating both automation of an ergonomic method (OWAS) and a biomechanical model for estimation of the compression forces acting upon the lumbosacral discs.

Results:

A validated measuring system is available which has been employed successfully in numerous field applications. The measured values which it delivers have provided valuable information for prevention measures in specific occupations. The measurement procedure developed by the BG Institute for Occupational Safety - BIA has been patented in seven countries. Extension of the measurement procedure to include the upper limb is in preparation.

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