With worldwide annual hip fracture rates predicted to exceed six million by 2050, the need to identify and intervene effectively in those at risk of hip fracture is of profound scientific, social and economic importance. The distribution of cortical bone in the proximal femur is believed to be the key determinant of fracture resistance and we have made rapid advances in the development of a novel imaging biomarker of hip fragility that has the potential to revolutionise hip fracture prediction and has already identified for the first time the precisely targeted response of osteoporotic hips to bone-building treatments.
The 2009 patented technique effectively de-blurs in-vivo CT data from clinical scans, enabling assessment of regional thinning by means of a colour map of cortical thickness. Our recent studies have shown that the effects on cortical bone of the bone building drug teriparatide (parathyroid hormone peptide 1-34) are targeted to sites of mechanical loading. The practical healthcare implication of this finding is that bone-active drugs may need to be administered alongside targeted exercise to maximise bone strength.
Another new approach to non-invasive in vivo bone imaging is the MR-based technique of structural spectroscopy, which enables site-specific assessment of cortical and trabecular bone microarchitecture in the axial and appendicular skeleton. We are currently conducting a study with Osteotronix, who have developed this technology, to determine the ability of this technique to predict bone fragility and fracture risk in patients with low bone mineral density. In collaboration with a group at Guys and St Thomas' Hospital, London, we are also investigating the utility of fluoride-labeled PET-scanning to measure regional bone blood flow and bone turnover, using comparison with directly assessed indices of bone turnover in iliac crest biopsies.
Analysis of the database from our Fracture Liaison Service, which is funded by the BRC, resulted in the new observation that fractures in obese postmenopausal women make a major contribution to the global fracture burden in this population. Collaborations have been forged with large international population-based prospective studies to pursue further these findings and to establish the pathogenesis of fractures associated with obesity. Important findings to date have been that obesity is a risk factor for certain fracture types, particularly fractures of the ankle and lower leg, and that poor physical function and increased risk of falling are important determinants of fracture risk in these women.
