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 c ord 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 t hree 20 year age groups (20-39, 40-59, and 60(+) years of age). BMD me asurements were obtained using dual energy X-ray absorptiometry (DEXA, Lunar Model DPX). BMD levels taken within the first year of injury we re not significantly lower than the age-matched able-bodies controls. The 20-39 year old patients injured longer than 1 year had significant ly lower (P less than or equal to 0.01) BMDs in their femoral region t han both their age matched controls and the 20-39 year old acutely inj ured (injured for less than 1 year) patients. Although femoral BMDs of both paraplegic and quadriplegic patients 40-59 and 60(+) years of ag e decreased over time, none showed significant bone loss in this regio n until 10 years after their injury. These results indicate that spina l cord injury associated bone loss occurs most dramatically in the fem oral region of young men. These results also indicate that initial bon e mass loss does not occur prior to 1 year post-injury to the extent t hat it is detectable by densitometry, or at least it did not occur in our patients.