Which sacral pattern is indicated by deep sacral bases with shallow ILAs?

• A. Bilateral flexion
• B. Bilateral extension
• C. Anterior torsion
• D. Posterior torsion

Answer: (A)

The main idea here is recognizing how the sacrum moves when it flexes on both sides. When the sacrum undergoes bilateral flexion, the base tilts forward toward the pubic symphysis and presents as a deeper, more anterior base on palpation. At the same time, the posterior landmarks become less prominent, so the inferior lateral angles feel shallow. This combination—deep sacral bases with shallow ILAs—is the classic bilateral flexion pattern.

In contrast, bilateral extension would show the base less prominent (shallower) and the ILAs more prominent (deeper), and torsions would produce asymmetry between sides rather than a symmetric pattern.