The instrumentation of anterior vertebral body screws has become an important
approach for the treatment of unstable fractures or curvature of the spine,
but little attention has been paid to the starting point of placing the screws
and the variability of the rib head position. We analysed the variability of rib
head position in a Chinese population in terms of the spinal canal and vertebral
body using computed tomography (CT). Images from transverse CT scans of
the T4–T12 vertebral bodies of 30 normal individuals were 3-D reconstructed
and analysed for measurement of parameters which included: 1) distance between
the left (or right) anterior border of the rib head and the posterior (or
anterior) margin of the vertebral body [L(R)ARHP(A)VB]; 2) left (or right) transverse
dimension [L(R)TD]; 3) left (or right) posterior (or anterior) safe angle
[L(R)P(A)SA]; and 4) distance between the inferior border of the left (or right) rib
head and the superior (or inferior) end-plate in the sagittal plane [I L(R)RHS(I)EP].
The ARHPVB, PSA, and IRHIEP gradually decrease, but ARHAVB, TD, ASA, and
IRHSEP gradually increase, from T4 to T12, indicating that the position of the
rib head changes from a more anterior position to a more posterior position
and from a more superior position to a more inferior position, as the number of
the vertebra increases. Our study has provided a comprehensive reference guide
for accurate and safe instrumentation of vertebral body screws in treating related
spine diseases. (Folia Morphol 2010; 69, 4: 232-240
