Densitometric patterns of spinal cord injury associated bone loss

The purpose of the study was to use dual energy X-ray absorptiometry to measure bone mineral density (BMD) in the lumbar spine, the femoral neck, Ward's triangle, and the greater trochanter in 204 men (69 able-bodies controls and 135 spinal cord injured patients) stratified according to age (20-39, 40-59, and 60+ years old) in order to determine whether changes in BMD were age related, and to determine when these changes began to appear. The BMDs of the lumbar spine of both the 40-59 year old and the 60+ year old patients were significantly higher (P < or = 0.012) than the 40-59 year old and 60+ year old controls, respectively. The femoral region BMDs of the 20-39 year old and the 40-59 year old patients were all significantly lower (P < or = 0.027) than the 20-39 year old and 40-59 year old controls, respectively. When patients were grouped according to the time since their injury (0-1, 1-5, 6-9, 10-19, 20-29, 30-39, 40-49, and 50-59 years post injury) within the various age categories different results were obtained. In all the age categories, BMD loss occurred starting one year after spinal cord injury in the hip region. This bone loss took place gradually, reaching a significant plateau (P < or = 0.017) at 19 years post injury and then started improving. The spine BMD in our patient population never significantly decreased, and started improving as the age of the injury increased. Findings presented for the femoral regions were similar to other investigators' findings; however, the steady bone mass maintained in the lumbar area, which increased with age regardless of the age of the injury, with the bone mass loss in the hip area, were the most notable new findings.