Morphometric Analysis and a Novel Classification of the Hyoid Bone

Purpose: This study was conducted to investigate the shape, fusion status, and body width of the hyoid bone and to examine their relationship with age, sex, and with each other. Materials and Methods: A total of 406 neck computed tomography angiography images (203 females and 203 males) from individuals aged 2–95 years were retrospectively analyzed. Results: The most common shape was type 1 (outward), and the least common was type 4 (asymmetrical). Type 2 (inward) was significantly more frequent in males ( P = 0.002). Fusion incidence increased with age, and no fusion was observed under the age of 20. The first bilateral fusion was seen in a 22-year-old male, and the first unilateral fusion in a 25-year-old female. Although overall fusion rates did not differ significantly between sexes, fusion was observed at a younger mean age in females than in males (52.81 vs. 57.71 years). The mean hyoid body width was 2.25 ± 0.38 cm, greater in males ( P < 0.001), and showed a positive correlation with age in both sexes ( P < 0.001). Fusion status did not affect the hyoid type ( P = 0.85). Type 2 had significantly wider body width compared to type 1 ( P < 0.001), and body width was significantly narrower in nonfused bones compared to unilaterally and bilaterally fused ones ( P < 0.001). Conclusion: The novel classification system introduced here provides a practical tool for the rapid and consistent evaluation of hyoid morphology. Furthermore, this study fills a gap in the literature by demonstrating that fusion status does not affect hyoid bone type, whereas body width shows a partial association with morphology.