Bone microarchitecture involvement and intervertebral disc alterations in patients with β-thalassemia: a retrospective study

Abstract

Background. Bone involvement in patients with β-thalassemia is well known, but only few studies have analyzed bone microarchitecture and the prevalence of intervertebral disc calcifications (IDCs) in these patients.Aim: to evaluate the bone involvement in a group of patients with β-thalassemia in terms of geometry and bone quality; moreover, we evaluated prevalence and site of IDCs in these patients.Methods. Our retrospective case-control study was conducted in a population of adults with β-thalassemia, aged between 18 and 50 years. The patients were divided, according with the International Society for Clinical Densitometry, into 2 groups: subjects with Zs ≤ -2.0, below the expected range for age, and subjects with Zs > -2.0, within the expected range for age. Assessment of proximal femur geometry was performed using the Hip Structural Analysis (HSA), that provides the following parameters: Hip Axis Length (HAL), Femoral Strength Index (FSI), Cross-Sectional Moment of Inertia (CSMI) Cross-Sectional Area (CSA), Section Modulus (Z), and buckling ratio (BR). Assessment of bone quality was performed using the Trabecular Bone Score (TBS), stratifying subjects into 3 groups: with abnormal (TBS ≤ 1.200), partially altered (TBS> 1.200 and <1.350), and normal (TBS ≥ 1.350) trabecular microarchitecture. Finally, we evaluated the prevalence of IDCs highlighted by images of Vertebral Fracture Assessment (VFA).Results. We evaluated 49 patients with β-thalassemia, mean aged 35.16 ± 9.59 years, divided into two groups: 25 patients with Zs ≤ -2.0 and 24 patients with Zs > -2.0. Results demonstrated all statistically significant differences (p<0.001) between the two groups in BMD, Ts and Zs (in all examined districts), and in number of fragility fractures (p=0.0339). HSA showed that there are significant differences between groups only in FSI (p=0.0068) and CSA (p=0.0041). Furthermore, TBS of patients with Zs ≤ -2.0 was significantly lower than individuals Zs > -2.0 (p=0.0006); there was a statistically significant difference between the two groups in categorized TBS (p=0.0061). Finally, we evidenced in 7 patients (14.29%) the presence of at least one IDC.Conclusions. Our results showed that β-thalassemia is characterized not only by a reduction in BMD, but also by a geometric and qualitative bone microarchitecture involvement. HSA and even more TBS should be included in the assessment of individuals with β-thalassemia, in order to obtain a proper management and prevention of fragility fractures; furthermore, the presence of IDCs might be better investigated in these patients.