Dissociated hip and spine demineralization: a specific finding in spinal cord injury.

Bone mineral density of the lumbar spine and right hip was measured with dual x-ray absorptiometry in 14 men with chronic spinal cord injury (SCI). The pattern of demineralization was compared to that observed in 46 men with a variety of endocrine disorders (chronic steroid use seven, chronic neuroleptic use 15, prolactinoma three, hypogonadism six, hyperthyroidism three, idiopathic osteoporosis 12). The SCI patients had significant hip demineralization but normal bone density in the lumbar spine (percent of age-matched normal 86.0 +/- 3.8 for the femoral neck, 101.8 +/- 4.3 for the lumbar spine; t = 3.88, p = 0.002). In contrast, the endocrine disorders were associated with disproportionate lumbar spine demineralization (percent of age-matched normal 97.5 +/- 1.9 for the femoral neck, 81.8 +/- 2.0 for the lumbar spine; t = 8.98, p < 0.000001). We conclude that hip demineralization is a common complication of SCI but that lumbar bone density is well preserved. This pattern of highly selective bone loss from the hip appears to be unique compared to other endocrine causes of osteoporosis.