New research has highlighted a preventative treatment gap in patients prone to bone fractures who are otherwise healthy.
The study, led by Imperial College London, found that flexibility as well as density in the bone nanostructure is an important factor in assessing how likely someone is to suffer a femoral fracture.
In the cross-sectional study, nano- and tissue-level mechanics were compared across trabecular sections from the proximal femora of three groups (n=10 each): ageing non-fractured donors (control participants), untreated fracture patients and bisphosphonate-treated fracture patients.
Collagen fibril, mineral and tissue mechanics were measured using synchrotron X-Ray diffraction of bone sections under load. Mechanical data were compared across groups, and tissue-level data were regressed against nano.
Compared with control participants, fracture patients exhibited significantly lower critical tissue strain, max strain and normalised strength, with lower peak fibril and mineral strain. Bisphosphonate-treated participants exhibited the lowest properties. In all three groups, peak mineral strain coincided with maximum tissue strength (i.e. ultimate stress), whilst peak fibril strain occurred afterwards (i.e. higher tissue strain).
Tissue strain and strength were positively and strongly correlated with peak fibril and mineral strains.
Age-related fractures were associated with lower peak fibril and mineral strain, irrespective of treatment. The authors say this indicates that earlier mineral disengagement and the subsequent onset of fibril sliding is one of the key mechanisms leading to fracture. They say treatments for fragility should target collagen-mineral interactions to restore nano-scale strain to the healthy bone.
