What occurs during a posterior pelvic tilt?

• A. Rotates the pelvis backward on the femur and reduces lumbar lordosis
• B. Tilts the pelvis laterally around the vertical axis
• C. Tilts the pelvis forward increasing lumbar lordosis
• D. Rotates the pelvis around the femur causing hip adduction

Answer: (A)

During a posterior pelvic tilt the pelvis rotates backward on the femoral heads, which reduces the curve of the lower spine (lumbar lordosis). This tucks the tailbone under and flattens the lower back. This contrasts with tilting forward, which increases the lumbar curve, or tilting laterally or rotating in the transverse plane, which describe different movements not tied to changing lumbar lordosis. So the description that the pelvis moves backward and the lumbar curve decreases best matches what happens in a posterior pelvic tilt.