Shape Analysis of
Pediatric Thoracic Vertebra using Generalized Procrustes Analysis
Spine morphology changes rapidly between birth and skeletal maturity;
however, normative changes in thoracic vertebral morphology are not well
understood. Hence there is a need to study age-related structural variations in
the normative thoracic spine. This study quantifies vertebral shape change as a
function of age for the thoracic spines of subjects 1 to 18 years old.
Retrospective chest CT scans of skeletally normal subjects (55 female, 45 male)
obtained from CHOP were reconstructed using MIMICS v16 (Materialise, Belgium),
refined using 3-matic v8 (Materialise, Belgium), and exported to MATLAB r2011b
(The MathWorks, Inc., Natick, MA). 30 landmark points were identified on all
vertebrae using a custom MATLAB script. Generalized procrustes analyses were
performed on landmarks at each thoracic level and gender. Data analysis
suggests a correlation between landmark position and age. In the upper half of the
thoracic spine, the vertebral body expands axially with age while in the lower
half the vertebral body expands axially, laterally, anteriorly, and posteriorly
with age. The pedicles at all thoracic levels move medially and enlarge with
age as the spinous process extends towards the posterior inferiorly with age.
The facets and the posterior of the spinal canal at all thoracic levels move anteriorly
with age. The transverse processes above thoracic level eight move superiorly
with age while at levels eight and lower the transverse processes either move
insignificantly, or drift inferiorly with age. Average shape models like
these may be used to aid computational modeling, and the development of patient
specific parameterized models.
