Tomographic analysis of anatomical parameters of the axis in children.
OBJECTIVE
To carry out an anatomical study of the axis with the use of computed tomography (CT) in children aged from two to ten years, measuring the lamina angle, lamina and pedicle length and thickness, and lateral mass length.


METHODS
Sixty-four CTs were studied from patients aged 24 to 120 months old, of both sexes and without any cervical anomaly. The measurements obtained were correlated with the data on age and sex of the patients. Statistical analysis was performed using the Students "t" tests.


RESULTS
We found that within the age range 24-48 months, 5.5% of the lamina and 8.3% of the pedicles had thicknesses of less than 3.5mm, which is the minimum thickness needed for insertion of the screw. Between 49 and 120 months, there were no lamina thicknesses of less than 3.5mm, and 1.2% of the pedicle thicknesses were less than 3.5mm values. Neither of the age groups had any lamina and pedicle lengths of less than 12mm, or lateral mass lengths greater than 12mm.


CONCLUSIONS
The analysis of the data obtained demonstrates that most of the time, is possible to use a 3.5mm pedicle screw in the laminas and pedicles of the axis in children.


METHODS
II, Development of diagnostic criteria in consecutive patients.
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Alessandro Gonzalez
AG
Torelli
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Rafael Bellucci
RB
Kohlmann
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Olavo Letaif
OL
Biraghi
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Alexandre Sadao
AS
Lutaka
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Alexandre Fogaça
AF
Cristante
Spine Group of the Institute of Orthopedics and Traumatology of Hospital das Clínicas of the School of Medicine of Universidade de São Paulo - São Paulo, SP, Brazil.
Raphael Martus
RM
Marcon
Axis; Bone screws; Spinal fusion; Tomography