If 10 mm of AS is corrected, femur height changes by:

• A. -4 mm
• B. -2 mm
• C. +4 mm
• D. No change

Answer: (A)

When the sacral misalignment is corrected, the pelvis rotates to re-establish balance. The femur height measure is tied to how the pelvis and lower spine align, so only part of the sacral adjustment shows up as a change in femur height. In this balancing pattern, a correction of ten millimeters in the anterior direction translates to about four millimeters less in femur height. That’s why the femur height would decrease by four millimeters with that correction.