The gross osseous anatomy of the spine has been the subject of
much
study but the internal architecture and
trabecular anatomy of thoracolumbar vertebrate has not previously been
well described. This study is based
on high resolution x-ray images of 56 isolated thoracolumbar vertebrae
and
thick sections obtained from
them. A previously undescribed array of trabeculae was documented which
originated from the medial
corner of the base of the pedicles and extended in a radial array
throughout the vertebral body. This
trabecular array persisted even in severely osteoporotic specimens. The
cortex of the vertebral canal thinned
abruptly near the base of the pedicle creating what may be a stress
concentration at this site. This
corresponded to the site of origin of the trabecular array. The presence
of
this possible stress concentration,
in proximity to the trabecular array, may provide an explanation for the
trapezoidal shape of the bony
fragments that are frequently retropulsed into the spinal canal in axial
load type burst fractures, common in this area of the spine.