Evaluating the Ergonomics of Healthcare Providers using Kinematic Motion Analysis, Electromyography, and Musculoskeletal Modeling

Abstract

Work-related musculoskeletal disorders (MSDs) in healthcare providers have been heavily reported, and are a major cause of occupational discomfort, disability, and occupational absence. Current evaluation methodology of occupational posture in healthcare professionals includes qualitative methods such as survey-based instruments that report on the characteristics of existing pain, or observational instruments where still photographs or videos of occupational postures are evaluated by independent raters to assess risk or exposure to musculoskeletal disorders. This research program used marker-based kinematic motion capture, surface electromyography, and musculoskeletal modeling to evaluate occupational postures in eye care providers and dental operators. Reclining the patient during refraction and strabismus exams reduced the amount of procedural time that eye care providers’ necks were in non-neutral postures. For eye care providers performing the slit lamp exam, it was observed that moving the patient forward and adjusting slit lamp biomicroscope height led to reduced non-neutral neck postures as indicated by a reduction in sagittal plane neck flexion range of motion, upper trapezius muscle activity and the percentage of procedural time with non-neutral neck flexion. Additionally, the use of an elbow rest when holding up exam lenses at the slit lamp reduced the procedural time that the anterior deltoid muscle was active, indicating a lower likelihood of shoulder musculoskeletal disorders. For dental operators, this research investigated the effect of using two kinds of Galilean magnification loupes on neck postures in dental hygienists performing sub-gingival probing. It was observed that both loupes reduced the range of motion of sagittal plane neck flexion in dental hygienists when compared to no magnification. The use of two kinds of through-the-lens Galilean loupes used by ophthalmic surgeons was also evaluated using motion capture, electromyography, and musculoskeletal modeling. A musculoskeletal model of a 50th percentile adult male demonstrated that holding a human head balanced at the working neck flexion of a lighter loupe required a smaller angular torque than a heavier loupe. Since this lower torque was a function of both neck flexion and loupe weight, neck muscle activity was evaluated at three different neck flexions for both loupes. It was observed that using a lighter loupe with a larger angle of declination led to a decrease in upper trapezius muscle activity. Postural adjustment, patient positioning, equipment re-positioning and supportive equipment choice (such as elbow rests for slit lamp examinations, or magnification loupes for periodontal probing and ophthalmic surgery) may be easy to implement methods that can reduce the exposure of healthcare providers to work-related musculoskeletal disorders.