CHAPTER 37 ANATOMIC APPROACHES TO THE SPINE
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A B C
FIGURE 37.4 Pedicle dimensions of T3 (A), T8 (B), and L4 (C) vertebrae. Vertical diameter (c)
increases from 0.7 to 1.5 cm, horizontal diameter (d) increases from 0.7 to 1.6 cm with minimum of 0.5
cm in T5. Direction is almost sagittal from T4 to L4. Angle (e) seldom extends beyond 10 degrees. More
proximally, direction is more oblique: T1 = 36 degrees, T2 = 34 degrees, T3 = 23 degrees. L5 is oblique
(30 degrees) but is large and easy to drill. (Redrawn from Roy-Camille R, Saillant G, Mazel CH: Plating of
thoracic, thoracolumbar, and lumbar injuries with pedicle screw plates, Orthop Clin North Am 17:147, 1986.)
T3
T8
L4
c c
c
d
d
d
e
e e
A B
C D
FIGURE 37.5 A and B, Anteroposterior and lateral views of pedicle entrance point in
thoracic spine at intersection of lines drawn through middle of inferior articular facets and
middle of insertion of transverse processes (1 mm below facet joint). C and D, Anteropos-
terior and lateral views of pedicle entrance point in lumbar spine at intersection of two
lines. On typical bony crest, it is 1 mm below articular joint. (Redrawn from Roy-Camille R,
Saillant G, Mazel CH: Plating of thoracic, thoracolumbar, and lumbar injuries with pedicle screw
plates, Orthop Clin North Am 17:147, 1986).