Contributions of Severe Burn and Disuse to Bone Structure and Strength in Rats
ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
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Burn and disuse results in metabolic and bone changes associated with substantial and sustained bone loss. Such loss can lead to an increased fracture incidence and osteopenia. We studied the independent effects of burn and disuse on bone morphology, composition and strength, and microstructure of the bone alterations 14 days after injury. Sprague Dawley rats were randomized into four groups ShamAmbulatory SA, Burn Ambulatory BA, ShamHindlimb Unloaded SH and BurnHindlimb Unloaded BH. Burn groups received a 40 total body surface area full thickness scald burn. Disuse by hindlimb unloading was initiated immediately following injury. Bone turnover was determined in plasma and urine. Femur biomechanical parameters were measured by three point bending tests and bone microarchitecture was determined by micro computed tomography uCT. On day 14, a significant reduction in body mass was observed as a result of burn, disuse and a com bination of both. In terms of bone health, disuse alone and in combination affected femur weight, length and bone mineral content. Bending failure energy, an index of femur strength, was significantly reduced in all groups and maximum bending stress was lower when burn and disuse were combined. Osteocalcin was reduced in BA compared to the other groups, indicating influence of burn. The reductions observed in femur weight, BMC, biomechanical parameters and indices of bone formation are primarily responses to the combination of burn and disuse. These results offer insight into bone degradation following severe injury and disuse.
- Anatomy and Physiology
- Medicine and Medical Research