Cervical vertebral body growth and emergence of sexual dimorphism: a developmental study using computed tomography

Abstract

The size and shape of human cervical vertebral bodies serve as a reference for measurement or treatment planning in multiple disciplines. It is therefore necessary to understand thoroughly the developmental changes in the cervical vertebrae in relation to the changing biomechanical demands on the neck during the first two decades of life. To delineate sex‐specific changes in human cervical vertebral bodies, 23 landmarks were placed in the midsagittal plane to define the boundaries of C2 to C7 in 123 (73 M; 50 F) computed tomography scans from individuals, ages 6 months to 19 years. Size was calculated as the geometric area, from which sex‐specific growth trend, rate, and type for each vertebral body were determined, as well as length measures of local deformation‐based morphometry vectors from the centroid to each landmark. Additionally, for each of the four pubertal‐staged age cohorts, sex‐specific vertebral body wireframes were superimposed using generalized Procrustes analysis to determine sex‐specific changes in form (size and shape) and shape alone. Our findings reveal that C2 was unique in achieving more of its adult size by 5 years, particularly in females. In contrast, C3–C7 had a second period of accelerated growth during puberty. The vertebrae of males and females were significantly different in size, particularly after puberty, when males had larger cervical vertebral bodies. Male growth outpaced female growth around age 10 years and persisted until around age 19–20 years, whereas females completed growth earlier, around age 17–18 years. The greatest shape differences between males and females occurred during puberty. Both sexes had similar growth in the superoinferior height, but males also displayed more growth in anteroposterior depth. Such prominent sex differences in size, shape, and form are likely the result of differences in growth rate and growth duration. Female vertebrae are thus not simply smaller versions of the male vertebrae. Additional research is needed to further quantify growth and help improve age‐ and sex‐specific guidance in clinical practice.

Developmental morphology of the cervical vertebrae and the emergence of sexual dimorphism in size and shape: A computed tomography study

“…In addition, somatic growth type has a second period of growth during puberty that is not present in neural growth. In a recent study, growth of the cervical spines in the midsagittal plane revealed the cross‐sectional area of C2 to follow a neural growth type, while C3–C7 follow the somatic growth type (Miller, Hwang, Cotter, & Voreperian, 2019), supporting Scammon's report that growth of the neck is complex and does not reflect a single growth type, but rather a mixed or combination of growth types (Scammon, 1930).…”

“…For example, the descent of the larynx and positioning of the hyoid bone have been described by the relative position along the cervical spine such that the infant hyoid bone descends from C2 to the adult position when the superior margin of the hyoid body aligns with the C3/C4 junction (Bench, 1963; Boë et al, 2006; Carlsöö & Leijon, 1960; Lieberman, McCarthy, Hiiemae, & Palmer, 2001). A more thorough understanding of the directional growth of the individual cervical vertebrae (e.g., supero‐inferior heights and anteroposterior depths) would enhance assessments on relational growth, particularly since, as noted above, research findings have documented different growth trends and types for C2 versus C3–C7 (Miller et al, 2019).…”

“…Sexual dimorphism in size and shape of the cervical vertebral bodies is well documented (Chatzigianni & Halazonetis, 2009; Ezra et al, 2017; Hellsing, 1991; Johnson et al, 2016; Miller et al, 2019; Vasavada, Danaraj, & Siegmund, 2008). To date, research has focused on the comparison between adults (Been et al, 2017), the development of the upper (C1–C4) cervical vertebrae morphology (Chatzigianni & Halazonetis, 2009), or differences in growth trends (Johnson et al, 2016; Miller et al, 2019). Despite evidence on the presence of sexual dimorphism of the cervical vertebrae, the unisex standards of CVMI are currently used clinically.…”

Defining a Growing and Maturing Skeleton and its Relevance in Diseases that Affect Skeletal Growth, Such as X-Linked Hypophosphataemia (XLH)

“…The primary determinant for epiphyseal closure is timing of puberty and this step marks the end of longitudinal growth of the long bones and vertebrae and the attainment of final height [15,102]. Epiphyseal plate closure does not happen simultaneously in the skeleton and a study of union at the epiphyses at the knee involving young males/females aged 18-18.9 years showed that complete epiphyseal union of the femur, tibia and fibula occurred in males/ females in 12.5%/10%, 0%/10%, and 25%/60%, respectively [20,103,104].…”

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“…Vertebral bodies also grow via primary and secondary ossification centers, in a process where the vertebrae form shapes that optimize the protection of the spinal cord, aid general mobility and provide support for the head and neck. The vertebral bodies continue changing and adapting via endochondral ossification into adulthood as greater mobility and stability is required [20].…”