[The load on the spinal column in handling of burdens]

The health consequences of long-term professional activity in loading for transport were investigated in an epidemiological study. This involved determining the frequency of orthopedic diseases within a series of transport workers and comparing it with the disease frequency in a comparable group with the same age distribution. The frequency of orthopedic diseases in transport workers is about 22% higher than in the other group. Most of the findings relate to the lower lumbar spine. An increase in the number of diseases can be observed in the transport workers even after a short period of professional activity. In order to examine the possible cause for the increased frequency of disease, the load on the lower lumbar spine was determined quantitatively using biomechanical model calculations. A three-dimensional biomechanical model that allows examination of both static and dynamic load was developed for this purpose. The influence of posture, the mass of the load to be transferred, and the acceleration of the load and the body on the mechanical spinal load were examined as typical examples of load manipulation. In the assessment of load, the compressive forces calculated were compared with the strength of the spinal elements. The compression forces on the lower lumbar spine are of the same order of magnitude as the strength. The high mechanical load can therefore be regarded as a possible cause of the high frequency of disease among persons whose professional activity involves lifting heavy loads.