Bone Abstracts

Background and aims: Dual energy X-ray absorptiometry (DXA) as currently utilised has limitations in identifying patients with osteoporosis and predicting fractures, since most low-trauma fracture (LTF) patients have osteopenia not osteoporosis based on DXA assessment. We aimed to express peripheral quantitative computed tomography (pQCT) variables of patients with low-trauma fracture as T-scores by using T-score scales obtained from healthy young women, and to evaluate the potential clinical utility of pQCT to complement DXA for the assessment of bone fragility.

Methods: Fracture patients were recruited from a fracture liaison service at a tertiary hospital. Reference pQCT data were obtained from studies of women’s health conducted by our group. A study visit was arranged with fracture patients, during which DXA and pQCT measures were obtained to assess their bone strength.

Results: A total of 59 fracture patients were recruited, and reference data were obtained from 78 healthy 19–25 year-old females after screening for medical exclusions. All DXA variables and most pQCT variables were significantly different between healthy young females and fracture patients (P<0.05), except polar stress strain index (SSIp; P=0.15). Fracture patients were divided into osteoporosis and non-osteoporosis groups according to their DXA T-scores. Significant differences between these groups were observed in most pQCT variables (P<0.05), except trabecular area and cortical density (P>0.9 and P=0.5, respectively). By applying pQCT T-scores, 15 (37%) LTF patients who were classified as low/medium risk of fracture on DXA T-scores alone were reclassified as high risk. Results of logistic regression suggested trabecular volumetric BMD and SSIp were independent predictors of fracture risk status.

Conclusions: More patients can be identified as having high fracture risk by applying pQCT T-score variables in older people with low-trauma fracture. Peripheral QCT T-scores contribute to the understanding of bone fragility in this population.