Time-course Of Cancellous And Cortical Bone Loss In A Rodent Contusion Spinal Cord Injury Model: 2333 Board #80 May 29, 11

Rodent spinal cord injury (SCI) models are commonly used to assess preclinical interventions designed to restore musculoskeletal integrity. However, relatively few rodent contusion SCI models simultaneously demonstrate cortical and cancellous bone loss, hallmark characteristics of the clinical SCI population. PURPOSE: To characterize the time-course of cortical and cancellous bone loss in a skeletally-mature rodent contusion SCI model. METHODS: Sixty male Sprague-Dawley rats aged 20 weeks received SHAM surgery or T9 laminectomy plus moderate/severe contusion SCI and were sacrificed 1-, 2-, or 3-months post-surgery. RESULTS: No cancellous or cortical bone deficits were present in 1-month SCI animals at the femoral metaphysis or diaphysis, respectively (as assessed via microCT). In contrast, cancellous bone mineral density was 32-35% lower in 2-month (p<0.05) and 3-month animals (p<0.01), compared with respective SHAMs. These changes were characterized by a 57-60% lower cancellous bone volume versus SHAMs (p<0.05, 2-month; p<0.01, 3-month), an effect primarily resulting from reduced trabecular number (p<0.01). Trabecular pattern factor (an inverse measure of trabecular connectivity) was increased 18-20% (p<0.05, 2-month and p<0.01, 3-month) and structure model index (a measure of plate-/rod-like trabecular structures) was increased 7-9% (p=0.052, trend 2-month; p<0.01, 3-month) compared with SHAMs. At the femoral diaphysis, 2- and 3-month SCI animals exhibited 10% lower cortical thickness (p<0.01), 8% lower total bone area (p<0.05, 3-month only), 12-13% lower cortical area (p<0.01), and 5-6% lower cortical area fraction (p<0.05) compared with respective SHAMs. CONCLUSION: Cancellous and cortical bone deficits are present within 2 months of moderate/severe contusion SCI in skeletally mature male rodents. These deleterious morphological and microarchitectural alterations suggest compromised structural integrity occur in the femora of our rodent model, similar to that observed clinically after SCI, and indicate the viability of this model as a means of testing therapeutic interventions designed to prevent bone loss and/or regenerate bone subsequent to SCI. Supported by a Department of Veterans Affairs SPiRE Award to JFY.