Bone
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Fracture nonunion risk is related to severity of injury and type of treatment, yet fracture healing is not fully explained by these factors alone. We hypothesize that patient demographic factors assessable by the clinician at fracture presentation can predict nonunion. ⋯ A logistic model predicted nonunion with reasonable accuracy (AUC=0.725). Within the Medicare population, nonunion patients were younger than patients who healed normally. Fracture was associated with increased risk of death within 1year of fracture (p<0.0001) in 14 different bones, confirming that geriatric fracture is a major public health issue. Comorbidities associated with increased risk of nonunion include past or current smoking, alcoholism, obesity or morbid obesity, osteoarthritis, rheumatoid arthritis, type II diabetes, and/or open fracture (all, multivariate p<0.001). Nonunion prediction requires knowledge of 26 patient variables but predictive accuracy is currently comparable to the Framingham cardiovascular risk prediction.
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Clinically, vertebral fractures often occur in the upper lumbar spine and involve the superior endplate of a vertebra (which is immediately caudal to a disc). Knowledge that the cranial endplate of a disc is thicker and has greater bone mineral density (BMD) than the corresponding caudal endplate helps to explain this phenomenon. In this study, we investigated structural differences in vertebral trabeculae on either side of a lumbar disc to provide further insight into vertebral fracture risk. ⋯ Structural asymmetries of vertebral trabeculae were not associated with age, disc degeneration, or disc narrowing. Vertebral trabecular parameters cranial to the disc were greater than caudally in the upper but not in the lower lumbar region. Findings further explain why vertebral fractures are more common in the upper lumbar region and more frequently involve the endplate caudal to a disc.