Bone density loss in spinal cord injuries slowed by high doses of stress to bone

A 3-year clinical trial conducted by University of Iowa researchers has found delivering high doses of stress to bone through programmed electrical stimulation of the muscle can significantly slow the loss of bone density in patients with spinal cord injury. The study published in Osteoporosis International.

“The novelty of our study is we have designed a method for individuals with paralysis to stand (bear weight) while superimposing a dose of muscle force using programmed electrical stimulation of the muscle,” study author Richard Shields, PT, PhD, stated in a news release.

The findings, according to the release, reveal that high doses of muscle force can be effective for the significant reduction of bone loss.

Shields and his fellow researchers evaluated several groups: seven patients who performed unilateral quadriceps stimulation in a supported stance while undergoing a compressive 150% body weight load (high dose) in one leg and 40% body weight load (low dose) in the other; five patients who stood passively with no application of quadriceps electrical stimulation to either leg (40% body weight or low dose); 15 patients who performed no standing at all (no dose) and 14 who did not display any spinal cord injury. Participants performed their training five times per week for 3 years.

Bone mineral density, according to the abstract, was tested between one and six times throughout the 3-year training protocol.

According to the release, after the 3-year study period average bone mineral density in the femur was almost 40% lower in patients who received low dose or no dose load when compared with patients who received high dose. The results also indicated high-dose load slowed the deterioration of trabecular bone. The abstract noted no differences between the low dose and untrained groups, suggesting bone mineral density for those patients who performed passive standing did not differ from patients who performed no standing.

“Keeping 40% of the bone material in the bone should translate to improved overall health along several dimensions, including the risk of fracture, as well as reducing other common complications stemming from SCI, like kidney stones and diabetes,” Shields stated in the release.

Reference:
Dudley-Javoroski, Saha P, Liang G, et al. High dose compressive loads attenuate bone mineral loss in humans with spinal cord injury. Osteoporos Int. 2011. doi: 10.1007/s00198-011-1879-4

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