Results of this study confirmed with real-world data that rib fracture patterns in unbelted occupants were more distributed and symmetric across the thorax compared to belted occupants in crashes with a deployed frontal airbag. Other factors, such as occupant kinematics and occupant age, also produced differing patterns of fractures. Normative data on rib fracture patterns in real-world occupants can contribute to understanding injury mechanisms and the role of different causation factors, which can ultimately help prevent fractures and improve vehicle safety.

Despite the evidence suggesting that between 8% and 55% of manual labourers experience thoracic pain, research on spinal loading during occupational tasks has been almost invariably limited to the lumbar spine. In this study, we determined the ratio of thoracic to lumbar compression force and the relative risk of injury to each region in various postures. Compressive forces on the spine were calculated based on previously reported thoracic and lumbar intradiscal pressures and disc cross-sectional areas. Flexion postures were associated with an approximate doubling in lumbar compression force but only small increases (or even decreases) in thoracic compression. The ratio of thoracic to lumbar compression was above the tolerance ratio (i.e. the ratio of thoracic to lumbar compressive strength) during upright postures and below the tolerance ratio during flexion postures, indicating that upright postures may pose a greater relative risk of injury to the thoracic spine than to the lumbar spine. Practitioner summary: Previously reported thoracic and lumbar in vivo disc pressures during various postures were compared. The ratio of thoracic and lumbar compression increased during upright postures and decreased in flexed postures, indicating that upright postures may pose a greater risk of injury to the thoracic spine than to the lumbar spine.

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Job design that is protective of the lumbar spine may inadvertently increase stresses on the thoracic spine, potentially leading to thoracic injury. In this study, we determined the ratio of thoracic to lumbar loading during various tasks, including stoop and squat lifts. Loading on the thoracic spine was calculated based on previously reported thoracic intradiscal pressures and cross-sectional areas, and compared to loading on the lumbar spine calculated using the same methodology. Results demonstrated that the ratio of thoracic and lumbar loading is not uniform and varies with the posture used during manual material handling tasks. Specifically, the loading of the thoracic spine increased during squat lifts, as compared to stoop lifts, whereas the loading on the lumbar spine decreased during squat lifts. This study adds to the body of knowledge that there are trade-offs between squat and stoops lifts and neither are without risks.