Which test is used to assess sacral motion by evaluating sacral sulci and mobility?

• A. MRI
• B. Ultrasound
• C. Spring test with palpation of sulci
• D. X-ray

Answer: (C)

Assessing sacral motion relies on hands-on palpation of the sacral sulci and a springing maneuver to judge how freely the sacrum moves. The sacral sulci are the indentations on either side of the sacral base, and their depth and symmetry reflect the sacrum’s position relative to the ilia. By applying a gentle spring to the sacrum through the posterior pelvis, you evaluate its anterior-posterior mobility. A normal, easily springing sacrum with symmetrical sulci indicates balanced motion; a loss of spring or asymmetrical sulci points to a sacral dysfunction such as a torsion or extension pattern. Imaging tests like MRI, ultrasound, or X-ray show anatomy but do not assess dynamic sacral motion in this way, so they aren’t used for this particular evaluation.