European Spine Journal

, Volume 15, Issue 12, pp 1785–1795

The effect of osteoporotic vertebral fracture on predicted spinal loads in vivo

Authors

    • Centre for Health, Exercise and Sports Medicine, School of PhysiotherapyUniversity of Melbourne
    • Department of Medicine, Royal Melbourne HospitalUniversity of Melbourne
  • Tim V. Wrigley
    • Centre for Health, Exercise and Sports Medicine, School of PhysiotherapyUniversity of Melbourne
  • Jaap H. van Dieën
    • Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement SciencesVrije Universiteit
  • Bev Phillips
    • Rehabilitation Sciences Research Centre, School of PhysiotherapyUniversity of Melbourne
  • Sing Kai Lo
    • Faculty of Health and Behavioural SciencesDeakin University
  • Alison M. Greig
    • Centre for Health, Exercise and Sports Medicine, School of PhysiotherapyUniversity of Melbourne
    • Department of Medicine, Royal Melbourne HospitalUniversity of Melbourne
  • Kim L. Bennell
    • Centre for Health, Exercise and Sports Medicine, School of PhysiotherapyUniversity of Melbourne
Original Article

DOI: 10.1007/s00586-006-0158-0

Cite this article as:
Briggs, A.M., Wrigley, T.V., van Dieën, J.H. et al. Eur Spine J (2006) 15: 1785. doi:10.1007/s00586-006-0158-0

Abstract

The aetiology of osteoporotic vertebral fractures is multi-factorial, and cannot be explained solely by low bone mass. After sustaining an initial vertebral fracture, the risk of subsequent fracture increases greatly. Examination of physiologic loads imposed on vertebral bodies may help to explain a mechanism underlying this fracture cascade. This study tested the hypothesis that model-derived segmental vertebral loading is greater in individuals who have sustained an osteoporotic vertebral fracture compared to those with osteoporosis and no history of fracture. Flexion moments, and compression and shear loads were calculated from T2 to L5 in 12 participants with fractures (66.4 ± 6.4 years, 162.2 ± 5.1 cm, 69.1 ± 11.2 kg) and 19 without fractures (62.9 ± 7.9 years, 158.3 ± 4.4 cm, 59.3 ± 8.9 kg) while standing. Static analysis was used to solve gravitational loads while muscle-derived forces were calculated using a detailed trunk muscle model driven by optimization with a cost function set to minimise muscle fatigue. Least squares regression was used to derive polynomial functions to describe normalised load profiles. Regression co-efficients were compared between groups to examine differences in loading profiles. Loading at the fractured level, and at one level above and below, were also compared between groups. The fracture group had significantly greater normalised compression (= 0.0008) and shear force (< 0.0001) profiles and a trend for a greater flexion moment profile. At the level of fracture, a significantly greater flexion moment (= 0.001) and shear force (< 0.001) was observed in the fracture group. A greater flexion moment (= 0.003) and compression force (= 0.007) one level below the fracture, and a greater flexion moment (= 0.002) and shear force (= 0.002) one level above the fracture was observed in the fracture group. The differences observed in multi-level spinal loading between the groups may explain a mechanism for increased risk of subsequent vertebral fractures. Interventions aimed at restoring vertebral morphology or reduce thoracic curvature may assist in normalising spine load profiles.

Keywords

OsteoporosisVertebral fractureSpine loadingBiomechanicsOptimization

Copyright information

© Springer-Verlag 2006