Manual patient handling commonly induces high mechanical load on the lower back of healthcare workers. A long-term research project, the 'Third Dortmund Lumbar Load Study' (DOLLY 3), was conducted to investigate the lumbar load of caregivers during handling activities that are considered 'definitely endangering' in the context of worker's compensation procedures. Nine types of handling activities in or at a bed or chair were analysed. Measurement of action forces via specifically developed devices and posture recording by means of optoelectronic marker capturing and video recordings in order to quantify several lumbar-load indicators was previously described in detail. This paper provides the results of laboratory examinations and subsequent biomechanical model calculations focused on lumbar load and the potentials of load reduction by applying biomechanically 'optimized' transfer modes instead of a 'conventional' technique and, for a subgroup of tasks, the supplementary usage of small aids such as a sliding mat or a glide board. Lumbosacral-disc compressive force may vary considerably with respect to the performed task, the mode of execution, and individual performance. For any activity type, highest values were found for conventional performance, lower ones for the improved transfer mode, and the lowest compressive-force values were gathered when small aids were applied. Statistical significance was verified for 13 of these 17 comparisons. Analysing indicators for asymmetric loading shows that lateral-bending and torsional moments of force at the lumbosacral disc may reach high values, which can be reduced considerably by implementing an improved handling mode. When evaluating biomechanical loads with respect to age- and gender-specific work-design limits, none of the analysed tasks, despite execution mode, resulted in an acceptable load range. Therefore, applying a biomechanically adequate handling mode combined with small aids to lower the friction between patient and surfaces is highly recommended, especially to prevent overload in older caregivers.
