Longitudinal study of the bone mineral content and of soft tissue composition after spinal cord section

Abstract

We present the results of a 1 year longitudinal study of bone mineral measurements and soft tissue composition in supra- and infra-lesional areas of 31 patients with a spinal cord injury (level D2-L3). Like others, we observed a rapid decrease of BMC in the paralysed areas, of approximately 4%/month during the first year in areas rich in trabecular bone and of approximately 2%/month in areas containing mainly compact bone. Lean soft tissue mass (muscle mass) decreases dramatically during the first months post injury in the legs, while fat content tends to increase. Though lean mass is better maintained in patients who develop spasticity, the evolution of BMC does not differ significantly between the groups of flaccid and spastic patients. In patients with partial or complete neurological recovery, a deficit in BMC of approximately 10% with regards to the initial value is still observed at 1 year in the lower limbs. The lean mass of the upper limbs increases early after the cord injury, because of intensive rehabilitation. No significant change in BMC was observed in the supra-lesional areas. These data confirm the rapid loss of bone in the paralysed areas of paraplegic patients, which occurs independently of the presence of spontaneous muscle activity or of passive verticalisation. In patients with recovery, BMC does not return to pre-injury values within 1 year. Thus, there would be an interest in preventing bone loss early in the course of the disease.