Measurement of action forces and posture to determine the lumbar load of healthcare workers during care activities with patient transfers.

Moving patients or other care activities with manual patient handling is characterized by high mechanical load on the lumbar spine of healthcare workers (HCWs). During the patient transfer activity, the caregivers exert lifting, pulling, and pushing forces varying over time with respect to amplitude and direction. Furthermore, the caregivers distinctly change their posture and frequently obtain postures asymmetrical to the median sagittal plane, including lateral bending and turning the trunk. This paper describes a procedure to determine lumbar load during patient transfer supported by measurement techniques and an exemplary application; this methodology represents the basis of a complex research project, the third 'Dortmund Lumbar Load Study (DOLLY 3)'. Lumbar load was determined by simulation calculations using a comprehensive biomechanical model ('The Dortmunder'). As the main influencing factors, the hand forces of the caregiver exerted during typical patient transfers and the posture and movements of the HCW were recorded in laboratory studies. The action forces were determined three-dimensionally with the help of a newly developed 'measuring bed', two different 'measuring chairs', a 'measuring bathtub', and a 'measuring floor'. To capture the forces during transfers in or at the bed, a common hospital bed was equipped with an additional framework, which is attached to the bedstead and connected to the bedspring frame via three-axial force sensors at the four corners. The other measuring systems were constructed similarly. Body movements were recorded using three-dimensional optoelectronic recording tools and video recordings. The posture and force data served as input data for the quantification of various lumbar-load indicators.