What is Nutation and Counternutation?

Nutation describes when the sacrum is rotated forwards relative to the iliac bones and Counternutation describes when the sacrum is rotated backwards relative to the iliac bones.

What causes Nutation and Counternutation?

Nutation occurs when the sacrum absorbs shock; it moves down, forward, and rotates to the opposite side. In rebound (counternutation) the sacrum moves up, backward, and rotates to the same side that absorbs the force. At the same time, the ilium rotates in the opposite direction.

Is Nutation a flexion or extension?

Anterior nutation (sacral flexion) is a nodding movement of the sacrum between the innominates, with the sacral base moving anteriorly and inferiorly and the sacral apex moving posteriorly and superiorly.

Is Nutation a posterior pelvic tilt?

Nutation can also be described as anterior tilt; counternutation can also be described as posterior tilt.

Which is the correct definition of counternutation?

Counternutation is simply movement in the opposite direction. Nutation is defined as a relative anterior tilt of the sacral base (upper flat surface of the sacrum that articulates with L5) in relation to the ilium (Figure 1).

Is there a balance between nutation and counternutation?

Therefore there may be some degree of relative nutation on one side and counternutation on the other. There is a delicate balance between stability and movement at the SI joint. While a small amount of nutation and counternutation are desirable, too much movement at this joint can lead to pain and biomechanical dysfunction.

How does counternutation differ from sacroiliac nutation?

For counternutation, the shifts are in the opposite direction: the iliac crests move laterally, the sacral promontory moves posteriorly, and the ischia move medially (from Kapandji, with permission). Figure 6.2a. The gross movements of the pelvis and sacrum that are involved in sacroiliac nutation are indicated by arrows.

What happens to the ilium during nutation and counternutation?

Nutation occurs when the sacrum absorbs shock; it moves down, forward, and rotates to the opposite side. In rebound (counternutation) the sacrum moves up, backward, and rotates to the same side that absorbs the force. At the same time, the ilium rotates in the opposite direction.