Abstract
Background Ideal internal fixation of the scaphoid relies on adequate bone stock for screw purchase;
so, knowledge of regional bone density of the scaphoid is crucial.
Questions/Purpose The purpose of this study was to evaluate regional variations in scaphoid bone density.
Materials and Methods Three-dimensional CT models of fractured scaphoids were created and sectioned into
proximal/distal segments and then into quadrants (volar/dorsal/radial/ulnar). Concentric
shells in the proximal and distal pole were constructed in 2-mm increments moving
from exterior to interior. Bone density was measured in Hounsfield units (HU).
Results Bone density of the distal scaphoid (453.2 ± 70.8 HU) was less than the proximal
scaphoid (619.8 ± 124.2 HU). There was no difference in bone density between the four
quadrants in either pole. In both the poles, the first subchondral shell was the densest.
In both the proximal and distal poles, bone density decreased significantly in all
three deeper shells.
Conclusion The proximal scaphoid had a greater density than the distal scaphoid. Within the
poles, there was no difference in bone density between the quadrants. The subchondral
2-mm shell had the greatest density. Bone density dropped off significantly between
the first and second shell in both the proximal and distal scaphoids.
Clinical Relevance In scaphoid fracture ORIF, optimal screw placement engages the subchondral 2-mm shell,
especially in the distal pole, which has an overall lower bone density, and the second
shell has only two-third the density of the first shell.
Keywords
scaphoid - bone density - subchondral - Hounsfield units
