High dose compressive loads attenuate bone mineral loss in humans with spinal cord injury

Osteoporos Int, 2012 · DOI: 10.1007/s00198-011-1879-4 · Published: September 1, 2012

Spinal Cord Injury Rehabilitation Musculoskeletal Medicine

Simple Explanation

People with spinal cord injury (SCI) lose bone and muscle integrity after their injury. Early doses of stress, applied through electrically induced muscle contractions, preserved bone density at high-risk sites. The study compared three doses of bone compressive loads at the distal femur in individuals with complete SCI who receive a novel stand training intervention. Over 3 years of training, 150% BW compressive load in upright stance significantly attenuated BMD decline when compared to passive standing or to no standing.

Study Duration

3 years

Participants

28 individuals with motor complete spinal cord injury and 14 without SCI

Evidence Level

Not specified

Key Findings

1
BMD for the High Dose group significantly exceeded BMD for both the Low Dose and the Untrained groups (p<0.05).
2
No significant difference existed between the Low Dose and Untrained groups (p>0.05), indicating that BMD for participants performing passive stance did not differ from individuals who performed no standing.
3
High-resolution CT imaging of one High Dose participant revealed 86% higher BMD and 67% higher trabecular width in the High Dose limb.

Research Summary

People with spinal cord injury (SCI) lose bone and muscle integrity after their injury. Early doses of stress, applied through electrically induced muscle contractions, preserved bone density at high-risk sites. The purpose of this study is to compare three doses of bone compressive loads: 0% BW (no standing), 40% BW with passive standing, and 150% BW induced by quadriceps stimulation during stance on BMD loss at the distal femur in individuals with complete SCI. Over 3 years of training, a high dose of compressive load (150% BW) administered via quadriceps activation in stance significantly attenuated BMD decline at the distal femur when compared to a low dose of load (passive standing) or no loading (no standing) in subjects with SCI.

Practical Implications

High-Dose Compressive Loading

High-dose compressive loading via quadriceps activation can help prevent bone loss in SCI patients.

Ineffectiveness of Passive Standing

Passive standing alone may not be sufficient to prevent bone mineral density decline.

Clinical Intervention Strategies

Clinicians can consider implementing quadriceps activation protocols to deliver targeted compressive loads for bone preservation.

Study Limitations

1
Training effects at the tibia sites were not detectable by pQCT but were apparent with high-resolution CT imaging
2
the quadriceps muscle was activated, which generated the primary stress through the distal femur during stance.
3
loads induced by muscle contractions are most concentrated over the bony sites that the muscle spans.

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