Biomechanical stresses on healthcare workers during manual patient bed-to-chair transfers

Healthcare workers are highly susceptible to musculoskeletal injury, particularly in their lower back and shoulders. Manual patient transfers are common and can generate physical stresses that contribute to these injuries. Few studies have used in vivo musculoskeletal modeling to estimate the effect of slide boards and patient cooperation, and none have used measured hand forces as an input to the models. This laboratory study evaluated manual, one-person bed to wheelchair transfers of a 64 kg simulated patient using an instrumented gait belt that measured hand forces. Thirteen healthcare workers performed transfers with and without a slide board and with up to three levels of vertical assistance (0, 18, and 36% of patient body weight). In vivo lower back forces and resultant shoulder moments were estimated with a thoracolumbar musculoskeletal model using directly measured hand forces and full-body motion capture. Results indicated that slide boards and vertical assistance reduce physical stresses. However, all transfer conditions had trials that exceeded an ergonomic guideline. To provide some guidance on when a transfer can safely be performed manually, a post hoc analysis was performed to estimate the patient mass that can be safely transferred manually under ideal circumstances with only a gait belt. These findings have the potential to guide and credibly educate healthcare workers on when manual transfers are appropriate and when lifts are required. Regardless, mechanical lifts are still recommended in most circumstances to protect caregivers from injury and the patient from falling.