Trunk Posture and Back Pain: Identification and Control of Occupational Risk Factors

Awkward trunk posture during work can be caused by a number of controllable factors, including poor work station layout, inappropriate design of tools and equipment, and/or incorrect work methods. If not eliminated, these postures can cause fatigue and contribute to the development of pain and disorders in the lower back. A computer-aided system was developed to evaluate trunk posture during work by measuring the time spent in neutral and non-neutral postures. This system was used to assess postural risk factors in a case-referent study of back disorders in an automobile assembly plant. The use of non-neutral trunk postures, such as forward flexion, lateral bending, and axial twisting, was associated with reports of back pain. The results of this study suggest that job redesign and/or other methods for controlling non-neutral posture be implemented to reduce the risk of back pain on industrial jobs. A general approach to work station design, based on a mechanical model of the human skeletal system, is described. This model is used to develop specific job-design guidelines to prevent awkward trunk posture.