Background: Fracture healing is a dynamic process, in which an inflammatory reaction induces bone resorption and formation in order to repair the fracture and restore bone strength. In contrast to plain radiographs, high resolution peripheral quantitative computed tomography (HR-pQCT) allows to visualize trabecular and cortical bone three dimensionally. From these 3D images bone strengths based on µFEA can be calculated.

Objectives: Evaluate the different stages of bone formation and bone resorption during the fracture healing process and relate the pattern of bone formation and resorption to the HR-pQCT derived bone parameters.

Methods: 18 women, aged 64±8 years, with a stable distal radius fracture were included and underwent HR-pQCT scanning (XtremeCT, Scanco Medical, Switzerland) of the fractured radius at 1-2 weeks post-fracture (baseline) and 3-4 weeks, 6-8 weeks and 12 weeks post-fracture. From the HR-pQCT images bone mineral density was assessed for the trabecular and the cortical region and using the 3D models, trabecular thickness and bone stiffness were calculated. Blood samples were collected at each visit for measurement of PINP, ICTP and hs-CRP. A linear mixed effect model with time post-fracture as fixed effect was used to detect significant changes from baseline. Correlations between the HR-pQCT parameters and the biomarkers were calculated using the Spearman’s correlation coefficient.

Results: During the fracture healing period, trabecular density and thickness and bone stiffness increased by 20%, 28% and 33%, respectively (all p<0.01), while cortical density decreased by 2.9% (p<0.05). Mean hs-CRP was 3.78±6.33 mg/L and was correlated negatively with the increase in trabecular density (r=-0.78, p<0.001) and PINP (r=-0.321, p<0.01). PINP temporarily increased and PINP and ICTP were intercorrelated at visit 1 and 2 (r=0.48, p<0.001). No significant correlations were found between the HR-pQCT parameters and the biomarkers.

Conclusions: These results open the perspective that a combination of HRpQCT and markers of inflammation and bone remodeling allow to study in detail the factors that are involved in normal and impaired fracture healing, and potentially also the effects of medications in optimizing the natural process of fracture healing.

Disclosure of Interest: J. de Jong: None Declared, S. Bours: None Declared, P. Willems: None Declared, J. Arts: None Declared, T. van Geel: None Declared, P. Brink: None Declared, B. van Rietbergen Consultant for: Scanco Medical AG, P. Menheere: None Declared, J. van den Bergh: None Declared, P. Geusens: None Declared