Pediatric dens anatomy and its implications for fracture treatment: an anatomical and radiological study

Abstract

Purpose

Separation of C2 growth plates and dens fractures are the most common types of injuries to the axis (C2) in children. Operative treatment of these injuries with the use of direct osteosynthesis requires a profound knowledge of detailed anatomy and dimensions of the axis. The main issue addressed by the study was the age at which the size of the dens is adequate at all levels to accommodate two screws, and the size of the posterior dens angulation angle (PDAA) in a healthy child in individual age periods.

Methods

Dimensions and angles of the dens and C2 in individual age categories in both boys and girls were measured in a series of 203 CT scans of individuals 0–18 years old and on anatomical specimens (42 samples). In addition, 5 histological series of this region from the fetal period were reviewed.

Results

Dimensions of the dens gradually increase with age, with a considerable acceleration during growth spurt periods that are different in boys and girls. PDAA is markedly changing with age; in the fetal period, the dens shows a slight anterior angulation which gradually transforms into posterior angulation, as early as between 4 and 6 years of age. The screw insertion angle changes accordingly.

Conclusion

During growth, there occur changes in PDAA that should be respected in evaluation of transformation of anterior into posterior angulation, as shown by imaging methods. Dens dimensions theoretically allow insertion of two 3.5 mm screws as early as from the age of 1 year.

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Funding

Supported by Ministry of Health, Czech Republic—conceptual development of research organization, Motol Univesity Hospital, Prague, Czech Republic 00064203—Jan Štulík. Petr Fojtík and Lucie Salavcová are grateful to Charles University for support in program of Specific University Research.

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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by GG, MB (CT scans) and LS, PF, ON (anatomical specimen). The first draft of the manuscript was written by JŠ and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Ondřej Naňka.

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We certify that the study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments.

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Štulík, J., Geri, G., Salavcová, L. et al. Pediatric dens anatomy and its implications for fracture treatment: an anatomical and radiological study. Eur Spine J (2020). https://doi.org/10.1007/s00586-020-06490-9

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Keywords

  • Pediatric C2 anatomy
  • Developmental changes
  • Posterior dens angulation angle
  • Screw insertion angle