High resolution peripheral computed tomography (HR-pQCT) in combination with finite element analysis (FEA) is a promising tool to assess the healing process of distal radius fractures. In a recently published pilot study, 18 fractures were scanned by HR-pQCT up to 12 weeks post-fracture. We here present the changes in bone parameters at the fracture side during a >2-year follow-up, compared with the same region at the contralateral radius. We included 18 post-menopausal women (mean age 64 years) with a stable distal radius fracture. HR-pQCT scans of the fracture region were performed at five visits scheduled at 1-2 (baseline), 3-4, 6-8, 12 weeks and >2 years post-fracture. At the last visit, the same region at the contralateral side was scanned as well. Bone density, micro-architectural and biomechanical parameters were calculated from the HR-pQCT scans in combination with FEA. Bone parameters at fracture side at each visit were compared to the bone parameters at contra-lateral side using a linear mixed-effect model. After >2-year follow-up the cortical fracture gaps were completely restored in all patients. The initial lower cortical density became comparable to the contra-lateral radius, while cortical thickness became higher (+20%, p=0.047). Trabecular density, number and thickness at fracture side were initially higher. While trabecular density and number decreased and became comparable with the contralateral radius, trabecular thickness remained higher at >2-year post-fracture (+52%, p<0.001). As a result, the initial lower torsional and bending stiffness became higher at the fracture side than at the contralateral radius after >2 years (+31%, p=0.016; and +29%, p=0.030, respectively). We conclude that during a period of >2 years post-fracture, fracture healing is still ongoing, with several cortical and trabecular bone parameters becoming higher than at the contralateral radius. This resulted in a restoration of bone stiffness at fracture side exceeding the stiffness at contralateral site.
Disclosure: B. van Rietbergen is a consultant for Scanco Medical AG. J.J. Arts is a board member of workgroup Biotechnology of the Dutch Orthopedic Association (NOV). P.C. Willems is a board member of the Dutch Spine Society (association of spine surgeons). This work was supported by the Weijerhorst Foundation (grant number WH2).