Bone mineral density in upper and lower extremities during 12 months afterspinal cord injury measured by peripheral quantitative computed tomography

Objective: To evaluate the loss of trabecular and cortical bone mineral den sity in radius, ulna and tibia of spinal cord injured persons with differen t levels of neurologic lesion after 6, 12 and 24 months of spinal cord inju ry (SCI). Design: Prospective study in a Paraplegic Centre of the University Hospital Balgrist, Zurich. Subjects and methods: Twenty-nine patients (27 males, two females) were exa mined by the highly precise peripheral quantitative computed tomography (pQ CT) soon after injury and subsequently at 6, 12 and in some cases 24 months after SCI. Using analysis of the bone mineral density (BMD), various degre es of trabecular and cortical bone loss were recognised. A rehabilitation p rogram was starred as soon as possible (1 - 4 weeks) after SCI. The influen ce of the level of neurological lesion was determined by analysis of varian ce (ANOVA). Spasticity was assessed by the Ashworth Scale. Results: The trabecular bone mineral density of radius and ulna was signifi cantly reduced in subjects with tetraplegia 6 months (radius 19% less, P < 0.01; ulna 6% less, P > 0.05) and 12 months after SCI (radius 28% less, P < 0.05; ulna 15% less, P < 0.05). The cortical bone density was significantl y reduced 12 months after SCI (radius 3% less, P < 0.05; ulna 4% less, P < 0.05). No changes in BMD of trabecular or cortical bone of radius and ulna were detected in subjects with paraplegia. The trabecular BMD of tibia was significantly reduced 6 months (5% less, P < 0.05) and 12 months after SCI (15% less, P < 0.05) in all subjects with SCI. The cortical bone density of the tibia only was decreased after a year following SCI (7% less, P < 0.05 ). No significant difference between both groups, subjects with paraplegia and subjects with tetraplegia was found for tibia cortical or trabecular BM D, There was no significant influence for the physical activity level or th e degree of spasticity on bone mineral density in all subjects with SCI. Conclusions: Twelve months after SCI a significant decrease of BMD was foun d in trabecular bone in radius and in tibia! of subjects with tetraplegia, In subjects paraplegia, a decrease only in tibia BMD occur-red. Intensity o f physical activity did not significantly influence the loss of BMD in all subjects with para- and tetraplegia. However, in some subjects regular inte nsive loading exercise activity in early rehabilitation (tilt table, standi ng) can possibly attenuate the decrease of BMD of tibia. Na influence was f ound for the degree of spasticity on the bone loss in all subjects with SCI .