Fracture Repair in the Distal Radius in Post-Menopausal Women: A Follow-Up Two Years Post-Fracture Using HRpQCT

Fracture healing is characterized by an intense increase in modeling and remodeling of bone, which allows removal of the cast after a stable distal radius fracture within 3-5 weeks. However, at that time bone strength has not recovered yet. We studied the changes in BMD, micro-architecture and bone stiffness after a distal radius fracture during a two-year follow-up in comparison to the contra-lateral side, and the association between the two-year stiffness and baseline BMD, micro-architecture, and early changes in these parameters. The fractured side of fourteen post-menopausal women (mean age 64 +/- 8) with a conservatively treated distal radius fracture was scanned by HRpQCT at 1-2, 3-4, 6-8 and 12 weeks and two years post-fracture. The same region contra-laterally was scanned as well at the two-year visit. BMD, micro-architecture and stiffness parameters were determined and the fracture side was compared to the contra-lateral side using a linear mixed-effect model. Spearman's correlation was used to correlate the two-year bone stiffness with baseline BMD, micro-architecture, and early three-month changes in these parameters. Two years post-fracture, cortical and trabecular thickness and torsional and bending stiffness were significantly higher at the fractured side as compared to the non-fractured side (21%, 55%, 31% and 29%, respectively, p < 0.05), while BMD was similar. Two-year torsional and bending stiffness correlated significantly with baseline BMD and cortical perimeter (|rho|>/=0.63, p < 0.016), but not with early changes in bone parameters. Using HRpQCT, this study illustrates that fracture healing is not completed by the time the cast is removed. We showed that from six weeks to two years post-fracture large changes occur in BMD, micro-architecture and biomechanical parameters at the fractured side, which were fully recovered after two years in comparison to the non-fractured contra-lateral side. Interestingly, higher two-year torsional and bending stiffness were associated with lower BMD and higher cortical perimeter at baseline. This article is protected by copyright. All rights reserved