J Štulík1, G Hodasová2, M Podhráský1, P Nesnídal1, P Fojtík3,4, O Naňka5. 1. Department of Spinal Surgery, First Faculty of Medicine, Teaching Hospital Motol, Charles University, V Úvalu 84, 150 06, Prague 5, Czech Republic. 2. Department of Imaging Methods, Second Faculty of Medicine, Teaching Hospital Motol, Charles University, V Úvalu 84, 150 06, Prague 5, Czech Republic. 3. Orthopedic Department, First Faculty of Medicine and Central Military Hospital, Charles University, U Vojenské nemocnice 1200, 169 02 Prague 6, Prague, Czech Republic. 4. Institute of Anatomy, First Faculty of Medicine, Charles University, U Nemocnice 3, 128 00, Prague 2, Czech Republic. 5. Institute of Anatomy, First Faculty of Medicine, Charles University, U Nemocnice 3, 128 00, Prague 2, Czech Republic. ondrej.nanka@lf1.cuni.cz.
Abstract
PURPOSE: The most common injuries to the upper cervical spine are fractures of the dens axis. Therefore, the purpose of our study was to answer three questions, namely (1) whether the size of the dens is adequate at all levels to accommodate two screws, (2) what the angle of the posterior tilt of the dens is in a healthy individual and (3) compare the measured variables between the sexes. METHODS: The cohort comprised 50 males and 50 females CT examination of the craniocervical junction. We measured the five diameters of the dens and posterior dens angulation angle (PDAA) and screw insertion angle (SIA). The same dimensions were measured in a control group, consisting of 40 non-pathological second cervical vertebrae specimens. RESULTS: On CT scans, the mean PDAA was 162.7 degrees in males and 160.26 degrees in females; the mean SIA was 62.0 degrees in males and 60.2 degrees in females. On specimens, the mean PDAA was 169.47 degrees in males and 166.95 degrees in females; the mean SIA was 65.42 degrees in males and 64.47 degrees in females. All obtained values were higher in males; regardless of their measuring on either CT scans or specimens, differences between males and females were statistically significant (p < 0.05) in a, c, d and e values. CONCLUSIONS: The values of our measurements correlate with the dimensions identified previously in other studies. Based on our clinical experience and measurements, we presume that two 3.5-mm screws can be inserted into the dens of all adult patients, except for those with pronounced anatomical anomalies. Posterior dens angulation angle is slightly larger than we expected. The dens is significantly larger in males almost in all measurement. These slides can be retrieved under Electronic Supplementary Material.
PURPOSE: The most common injuries to the upper cervical spine are fractures of the dens axis. Therefore, the purpose of our study was to answer three questions, namely (1) whether the size of the dens is adequate at all levels to accommodate two screws, (2) what the angle of the posterior tilt of the dens is in a healthy individual and (3) compare the measured variables between the sexes. METHODS: The cohort comprised 50 males and 50 females CT examination of the craniocervical junction. We measured the five diameters of the dens and posterior dens angulation angle (PDAA) and screw insertion angle (SIA). The same dimensions were measured in a control group, consisting of 40 non-pathological second cervical vertebrae specimens. RESULTS: On CT scans, the mean PDAA was 162.7 degrees in males and 160.26 degrees in females; the mean SIA was 62.0 degrees in males and 60.2 degrees in females. On specimens, the mean PDAA was 169.47 degrees in males and 166.95 degrees in females; the mean SIA was 65.42 degrees in males and 64.47 degrees in females. All obtained values were higher in males; regardless of their measuring on either CT scans or specimens, differences between males and females were statistically significant (p < 0.05) in a, c, d and e values. CONCLUSIONS: The values of our measurements correlate with the dimensions identified previously in other studies. Based on our clinical experience and measurements, we presume that two 3.5-mm screws can be inserted into the dens of all adult patients, except for those with pronounced anatomical anomalies. Posterior dens angulation angle is slightly larger than we expected. The dens is significantly larger in males almost in all measurement. These slides can be retrieved under Electronic Supplementary Material.
Entities:
Keywords:
C2 anatomy; C2 fracture; Dens fracture; Posterior dens angulation angle; Screw insertion angle
Authors: Patrick Platzer; Gerhild Thalhammer; Gerhard Oberleitner; Rupert Schuster; Vilmos Vécsei; Christian Gaebler Journal: J Bone Joint Surg Am Date: 2007-08 Impact factor: 5.284