Bone strength in girls and boys after a distal radius fracture: a 2-year HR-pQCT double cohort study.
Macdonald HM, Määttä M M, Gabel L, Mulpuri K, MckKay HA. Bone strength in girls and boys after a distal radius fracture: a 2-year HR-pQCT double cohort study. J Bone Miner Res. February 2018. DOI : 10.1002/jbmr.3307
Abstract
We recently reported impaired bone strength in girls with low‐ to moderate‐energy distal radius fractures (Fx) compared with girls with no history of forearm fractures (Non‐Fx). We aimed to determine whether bone strength deficits observed at baseline were still present after 2 years. We assessed bone strength, microarchitecture, and bone mineral density (BMD) of the non‐fractured (Fx) and non‐dominant (Non‐Fx) distal radius (7% site) at baseline, 12, and 24 months using high‐resolution pQCT (Scanco Medical, Brüttisellen, Switzerland) in 104 girls (aged 11.0 ± 1.7 years; 47 Fx, 57 Non‐Fx) and 157 boys (aged 12.7 ± 1.7 years; 86 Fx, 71 Non‐Fx). Bone outcomes included total area (Tt.Ar) and bone mineral density (Tt.BMD), trabecular bone volume ratio (BV/TV), thickness (Tb.Th), separation (Tb.Sp), and number (Tb.N), and cortical BMD (Ct.BMD), thickness (Ct.Th), and porosity (Ct.Po). We used finite element analysis to estimate bone strength (failure load [F.Load]; ultimate stress [U.Stress]; load‐to‐strength ratio). We used sex‐specific mixed‐effects models to compare bone outcomes between Fx and Non‐Fx over 2 years. In girls, those with fractures had 18% to 24% lower U.Stress and 5% to 9% lower Tt.BMD than Non‐Fx at all time points (p < 0.017). In secondary analysis by fracture degree, girls with low‐energy (LE) fractures had 19% to 21% lower F.Load, 25% to 47% lower U.Stress, 11% to 14% lower Tt.BMD, and 11% to 15% lower BV/TV than Non‐Fx at all time points (p < 0.017). In contrast, boys’ bone outcomes were similar between Fx and Non‐Fx at all time points. In secondary analysis by fracture degree, boys with LE fractures had 10% lower Tt.BMD and 10% lower Ct.Th compared with Non‐Fx at 12 months only. Deficits in distal radius bone strength and trabecular bone microarchitecture appear to track across 2 years after a forearm fracture in girls but not in boys. Longer follow‐up is needed to determine whether deficits persist into adulthood in women and how they may influence future risk of fragility fracture. © 2017 American Society for Bone and Mineral Research.