ResearchBiomechanics and neural control of the musculoskeletal system, utilizing anatomically-based models complemented with experimental data. Most of my research is focused on the human head and neck system.
Ergonomics of Mobile Devices
Forward or flexed head posture occurs frequently while using mobile devices and are implicated in neck pain, although the mechanisms are not well understood. We have quantified the increase in head and neck flexion and musculoskeletal load while subjects used tablet computers in different conditions (with and without a desk; with and without an accessory stand). We calculated gravitational demand, a measure of load required by neck muscles to hold up the head, which is related to increased soft tissue loads on other neck structures (e.g., facet joints, intervertebral discs) and neck muscle fatigue. We found that gravitational demand in tablet usage conditions increased 3-5 times the gravitational demand in neutral posture.
Postural stability of the human head and neck
Neck muscles are important for both static postural stability (i.e., holding up the head) and restoring head posture under dynamic conditions, such as those that might occur during a blow to the head or an automobile accident (e.g., whiplash injury). When muscles are unable to stabilize the head, it can lead to injury and chronic neck pain. We are examining how the activation of neck muscles complements passive tissue stiffness to achieve postural stability using experimental studies in human subjects integrated with biomechanical model analysis.
Mechanisms of whiplash injury
The anatomical site and mechanism of injury during whiplash (a rapid acceleration of the head and neck) are still unclear. We have utilized a biomechanical model of the neck musculoskeletal system with experimental data of human subjects undergoing 5 mph whiplash-like perturbations to calculate the strains, and thus potential for injury, in neck muscles.
Gender differences in the neck musculoskeletal system
The goal of this work is to evaluate factors responsible for the increased incidence of whiplash injury and neck pain in females vs. males. We have found that female neck geometry is not a simple scaled version of male neck geometry, which implies that gender-specific biomechanical models are necessary to evaluate gender differences in neck musculoskeletal disorders. We are currently developing a biomechanical model of the female neck musculoskeletal system.
Improving the geometric representations of neck muscles in biomechanical models
Our current models of the neck musculature represent neck muscles as straight lines. We are incorporating curved muscle paths into our models by defining geometrical constraints that approximate the curved neck muscle paths based on magnetic resonance imaging (MRI) data.