Thoracic and Lumbar Spine Biomechanics

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Low back pain continues to cost Canadian industries billions of dollars despite numerous research studies, which suggests that we do not yet adequately understand the spine. Given that the spine is a flexible multisegment column that requires active muscle and passive tissues to maintain its form, it is logical that there would be interplay across regional biomechanics and neuromuscular control. However, very few studies have investigated the thoracic spine influences the development of pain and injury in the lumbar spine. Complex loading, such as axial rotation with non-neutral flexion/extension postures, is the typical type of lumbar spine loading experienced in-vivo when performing routine activities of daily living and work tasks yet rarely used in research. These types of exposures have been recognized as risk factors for developing low back injuries in epidemiological studies. Often work must be performed in a prolonged seated or standing postures. Recent evidence demonstrates that these exposures can elicit pain, likely from altered neuromuscular control (i.e. co-activation). This work also notes a difference between the responses of men and women. While it is acknowledged that tolerance values may be modified non-linearly by these factors, current biomechanical models do not mitigate the risk with these parameters likely, due to a lack of usable data. My research that has shown complex loading increases risk of injury, and that lumbar spine motion, muscle activity, and load instability cannot fully explain lumbar responses, has led me to the long term objective of my research program: to reduce the incidence of work-related musculoskeletal disorders, particularly those associated with repetitive complex spine loading exposures; and to provide an improved characterization of the spine that industrial engineers, ergonomists, and health care providers can integrate into workplace design methods, risk identification and assessment tools, and more effective treatment and rehabilitative programs.