Analysis of Cortical Bone Structures in Perimenopausal Female Patients With Recent Fragility Fractures

Abstract

Aims: The aim of this study was to investigate trabecular and cortical bone microstructure in perimenopausal patients with atraumatic peripheral or vertebral fractures. We hypothesize that in perimenopausal women cortical bone is more affected by osteoporosis than trabecular bone. Methods: We consecutively investigated 26 perimenopausal treatment naive female patients (mean age: 47.8 yrs) with peripheral fractures (PG) and compared them to ageand sex-matched healthy controls (CG; n538; mean age 42.7 yrs). Patients had an average of two atraumatic fractures, but were otherwise healthy. The distal radius and the ultradistal tibia of all patients were scanned on an HRpQCT scanner (XtremeCT, SCANCO Medical, Br€uttisellen, Switzerland). Trabecular bone volume fraction (BV/TV) from the volumetric BMD of the trabecular compartment (Tb.BMD), the peripheral region adjacent to the cortex (pTb.BMD) and the central trabecular region (mTb.BMD) were analyzed. From the binary trabecular ridge image, trabecular number (Tb.N) was measured using the direct 3D distance transform approach. Based on the densitometric BV/TV and direct Tb.N, trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were derived using traditional plate model assumptions, as has been described previously (Boutroy et al., JCEM 2005). To assess cortical bone microarchitecture, the trabecular and cortical compartment were segmented by automated algorithm (Burghardt et al., JBMR 2009). We analyzed cortical BMD (Ct.BMD), cortical porosity (Ct.Po), cortical pore volume (Ct.Po.V), cortical pore diameter (Ct.Po.Dm) and cortical pore diameter distribution (Ct.Po.Dm.SD). Results: Structural analysis by HR-pQCT showed significant differences between patients and healthy controls regarding cortical but not trabecular parameters at both sites. At the radius patients had increased cortical pore volume (7.74 4.97mm vs. 5.29 3.78; p!0.01), increased cortical pore diameter (0.17 0.03mm vs. 0.15 0.02mm; p! 0.001) and an increased distribution of cortical pore diameters (7 3% vs. 4 3%; p!0.01) compared to controls. In addition, at the tibia cortical pore volume (61.15 30.66mm; p!0.01) and also cortical porosity (7 4% vs. 4 3%; p!0.01) were significantly increased. Strong correlations of cortical parameters were found between the tibia and radius. In addition, most cortical structure parameters were correlated with age in patients and controls. Conclusion: Our results suggest that bone fragility and fracture susceptibility in perimenopausal females are likely to contribute to poor cortical bone strength and increased cortical porosity. However, HR-pQCT resolution is limited and cortical porosity, analyzed by different algorithm, was reported to be much higher. Disclosure of Interest: None Declared