Demineralization in tetraplegic and paraplegic man over time

The aim of the present study was to compare bone mineral density (BMD in g/cm(2)) in the lumbar spine and three hip regions of male spinal cord injured subjects at various times post injury to age-matched able-bodied controls and to correlate their BMDs to their age and level of their spinal cord lesion. Patients and controls were stratified into three 20 year age groups (20-39, 40-59, and 60(+) years of age). BMD measurements were obtained using dual energy X-ray absorptiometry (DEXA, Lunar Model DPX). BMD levels taken within the first year of injury were not significantly lower than the age-matched able-bodies controls. The 20-39 year old patients injured longer than 1 year had significantly lower (P less than or equal to 0.01) BMDs in their femoral region than both their age matched controls and the 20-39 year old acutely injured (injured for less than 1 year) patients. Although femoral BMDs of both paraplegic and quadriplegic patients 40-59 and 60(+) years of age decreased over time, none showed significant bone loss in this region until 10 years after their injury. These results indicate that spinal cord injury associated bone loss occurs most dramatically in the femoral region of young men. These results also indicate that initial bone mass loss does not occur prior to 1 year post-injury to the extent that it is detectable by densitometry, or at least it did not occur in our patients.