Magnetic resonance imaging evaluation of coccyx morphology and morphometry in childhood

Abstract

Objectives: Pain around the coccyx is referred to as coccydynia. Inter coccygeal and sacrococcygeal angles as well as some types of coccyx may be associated with idiopathic coccydynia. The aim of this retrospective study was to evaluate the morphology and morphometry of the coccyx using MRI and to determine whether morphologic-morphometric features are associated with coccydynia in the pediatric population. Methods: This study was performed retrospectively on children aged 10–17 years who underwent pelvic and sacral magnetic resonance imaging for non-trauma related reasons. Inter coccygeal-sacrococcygeal angles and coccyx types were determined using sagittal T1- and T2-weighted images. Gender-specific assessments were made for intercoccigeal and sacrococcygeal angles as well as coccyx types based on Postacchinni and Massobrio classification. In statistical analysis, a p-value less than 0.05 was considered statistically significant. Results: One hundred and fifty-six children were included in the final analysis (108 girls, 48 boys). The mean age of the cases was 13.8 years (10–17). Type 1 was the most common type overall, accounting for 57.7% of the population. The sacrococcygeal angles of boys were significantly higher than those of girls. A significant negative correlation was found between age and sacrococcygeal angle. In children with Type 1 and Type 2 coccyx, girls had significantly higher intercoccigeal angles than boys. The intercoccigeal angle varied significantly in each coccyx type and the intercoccigeal angles increased significantly as the coccyx type increased (from Type 1 to Type 4). The most common coccyx type in the coccidynia group was Type 2, while the most common type in the control group was Type 1. The mean intercoccigeal angles of children with coccidynia were significantly higher than those of the control group. Conclusion: Coccydynia is a symptom with many possible reasons rather than a diagnosis. Coccyx morphology and morphometry can be associated with idiopathic coccydynia. To better understand these morphological and morphometric features, especially in the pediatric population, larger population studies are required.

Keywords

• coccyx
• intercoccygeal angle
• MRI
• sacrococcygeal angle

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