[Labor of freight-container tractor drivers and low-back pain. Characteristics of the low-back pain through clinical findings].

In order to clarify the characteristics of the low-back pain which is prevalent among freight-container tractor drivers, a medical examination, composed of orthopedic tests and questions about health conditions, was carried out on 231 tractor drivers. Prevailing complaints were: dullness or stiffness of the shoulder (71%); dullness of the neck (69%); dullness of the low back (62%); low-back pain (42%); dullness of the lower limbs (39%) and dullness of the back (36%). The rates of complaints of dullness or pain of the neck, shoulder, upper limbs, back or lower limbs, and disturbance of daily activity were associated with the grade of low-back pain evaluated from the subjective symptoms. Orthopedic examination revealed fatigue signs of muscles i.e. tenderness of the body trunk and limbs, tenderness or percussion pain on the spinous processes, and poor results in some tests on muscle strength. These findings were seen more frequently in the group with subjective symptoms, but even among the group without symptoms, they were evident to some degree. These findings were considered to originate from the fact that the freight-container tractors had many ergonomic problems and the daily driving hours of many drivers were estimated to exceed the allowable vibration exposure time of the ISO.