Effect of sex, age, and anthropometric parameters on the size and shape of vertebrae in densitometric morphometry. Results of the EPOLOS study

INTRODUCTION: Morphometric densitometry (morphometric X‑ray absorptiometry – MXA) allows to identify vertebral fractures, based on the objective measurement of vertebral dimensions. OBJECTIVES: The aim of the study was to assess the effect of sex, age, height, and body mass index (BMI) on selected parameters of vertebral size and shape measured by MXA. PATIENTS AND METHODS: A random study sample comprised 829 patients (520 women and 309 men) aged 20 to 79 years, none of whom had been previously treated for osteoporosis. Lateral densitometric scans of the thoracic‑lumbar spine (T4–L4) were performed using a fan-beam densitometer. Anterior (Ha), central (Hc), and posterior (Hp) vertebral heights were determined. RESULTS: The analysis included 9632 vertebrae. Higher values of Ha, Hc, and Hp were observed in men (P <0.001). The Ha/Hp ratio from T7 to L3 was lower in men compared with women (P <0.05). The Hc/Hp ratio was lower in T12 to L3 vertebrae in men (P <0.05). Wedging was significantly greater in men in thoracic vertebrae, and significantly lower in L3 and L4 (P <0.05). Concavity was similar in men and women in thoracic vertebrae from T5 to T10. We observed weak and moderate negative correlations between age and vertebral heights, Ha/Hp and Hc/Hp (P <0.001), and a moderate positive correlation between body height and vertebral heights (P <0.001). There were no statistically significant correlations between the body mass index and the remaining variables. CONCLUSIONS: Morphometric parameters of vertebrae vary depending on sex and age, which has to be considered when choosing reference groups. Knowledge about the differences in vertebral size and shape may prevent diagnostic errors and bias.