Relationship between Regional Bone Density Measurements and the Time since Injury in Adults with Spinal Cord Injuries

Objectives: To determine the bone mineral density (BMD) of the legs, arms, and trunk region of a group of adults with spinal cord injury (SCI) and to determine the relationship between regional BMD values and the time since injury. Design: BMD measurements were determined by total-body, dual-energy x-ray absorptiometry scans and percentage values (percentage-matched BMD), based on manufacturer-supplied normative data for age, sex, body weight, and ethnic group. The relationship between percentage-matched BMD values and time since injury was determined by linear regression analyses. Setting: Research laboratories in a university setting. Participants: Twenty-nine subjects (21 men, 8 women; mean age, 38.5y) who had sustained an SCI a mean of 10.6 years earlier (range, 0.6-35.3y). Interventions: Not applicable. Main Outcome Measure: The relationship between percentage-matched BMD values and the time since injury. Results: There was a significant inverse relationship between percentage-matched BMD leg (r²=-.76), arm (r²=-.45), and trunk (r²=-.38) values and the log of time since injury. Conclusion: Despite the varying levels of SCI and other relevant BMD contributing factors, the regional percentage-matched BMD values were significantly inversely related to the log of time since injury.