DonTigny [1-3] depicts a lesion which occurs in counternutation. He noted that, as one bends anteriorly, the ilium rotates anteriorly, inferiorly, and laterally on the sacrum. In this position, the gravitational weight line shifts from posterior to the pivot point of the innominates (the femoral heads) to the anterior. He stated that, if the abdominal muscles are weak, the injury occurs “from an anterior rotation of the innominate bones on the sacrum.” Anterior rotation of the innominates on the sacrum causes the short posterior ligaments to slacken and stresses the long posterior sacroiliac ligament, decreasing stability. He states that this mechanism would indicate a counternutation lesion since the long posterior ligament restricts counternutation and the innominates have rotated anteriorly into counternutation.

However, consideration should be given to the fact that the body’s weight is carried directly by the sacrum, and only indirectly by the innominates. Any inferiorly directed axial load would force the sacrum to rotate anteriorly and inferiorly, into nutation, ahead of the innominates. In this situation, it would also seem reasonable that the hamstrings, gluteus maximus, abdominals, and other hip extensors would rotate the ilia posteriorly; this counter-rotation induces nutation, stressing the ligaments that restrict nutation and, therefore, creates a nutation lesion.

Regardless of the position of the pelvis in relation to the gravitational line, it is the relationship of the sacrum to the ilium that defines nutation and counternutation. When a weight is lifted with an anteriorly tilted pelvis, the body has to resist the force of the load compounded by the leverage imposed by the horizontal distance of the weight from the sacroiliac joint. The forces on the nutation ligaments are significantly greater when lifting in anterior pelvic tilt than when lifting in the neutral stance, so a nutation lesion is the likely outcome in this situation – not a counternutation lesion.

Counternutation Lesion Possibilities
Speed Boat Analogy
It is plausible, however, that when the pelvis is rotated anteriorly and the upper body is supported so that the gravitational force is significantly reduced, a strong sudden force coming up from the legs can cause the innominates to rotate anteriorly with enough power to sprain the counternutation ligaments, but this scenario is unlikely. For example, when riding in a speed boat and leaning forward, with the upper body supported by the side of the boat, the shock of riding over waves, and landing hard, can drive the ilium into counternutation before the hip extensors can contract sufficiently to counter, especially in the presence of a nutation lesion in which the hip extensors would be inhibited and exhibit a slowed reaction time.

Nutation Lesion Chronicity
As the injury progresses, other complicating factors, such as compensation-to-compensation patterns may be found due to the muscles pulling the joints past neutral, into subluxation. For example, the counternutating force may be great enough, over time, to subluxate the sacrum posteriorly in relation to the ilium, creating a counternutation lesion (even though both may be rotated anteriorly, relative to the gravitational line).

Vleeming et al. [4, 5] showed that the long dorsal ligament (LDL) is commonly painful in pregnancy. They suggest that counternutation may be a “…pain-withdrawal-reaction to impairment elsewhere” They provide an example where, during pregnancy, nutation may stress the symphysis pubis and the pelvis may go into counternutation as a reaction to that stress. They suggest that “…pain in the LDL could be related to a strained LDL as a result of a repeated or sustained counternutated position in the SIJ and that the LDL is one of the explicit painful structures in the pelvic region.”

In both of the above examples, it is probable that the nutation lesion is the primary lesion, and the counternutation lesion is the result of either a slowed reaction of the inhibited muscles or structural positioning, both of which can occur as a result of the chronic muscular compensation pattern to a nutation lesion. Over time, this counternutation reaction may occur with any sacroiliac nutation lesion, creating a secondary lesion in the opposite direction, due to compensating muscular forces.

How to Tell the Primary Lesion
When both a nutation and counternutation lesion exist at the same time, the primary lesion can be determined by the muscular and/or structural adaptation. If counternutation is the major lesion, we should see a more pervasive reversed pattern of muscular tension/inhibition from what we see in the nutation lesion. Thus, on the side of lesion, we would see tightening of the nutation muscles, such as the ipsilateral lumbosacral multifidus, rectus abdominis, gluteus maximus/contralateral latissimus dorsi, etc., and inhibition of muscles that are tight in the nutation lesion, e.g., the ipsilateral piriformis, iliopsoas, quadratus lumborum, and other counternutation muscles described in this article. Structural distortions, as described above, should also be reversed. However, few observations of these reversed patterns are discussed in the literature and are usually evident only in local muscles, and may be explained as an over-compensation to a pre-existing nutation lesion.

One way to test is to mobilize the SIJ and see where the body settles; if it settles into a counternutation pattern on the side of injury, the original lesion is probably nutation.

References:
1. DonTigny, R.L., Evalutation, manipulation, and management of the anterior dysfunction of the sacroiliac joint. The D.O., 1973. 14(1).
2. DonTigny, R.L., Mechanics and Treatment of the Sacroiliac Joint. J Manipulative Physiol Ther, 1993. 1: p. 3-12.
3. DonTigny, R.L., Functional Biomechanics and Management of Pathomechanics of the Sacroiliac Joints. Spine: State of the Art Reviews, 1995. 9(2): p. 491-508.
4. Vleeming, A., et al., The function of the long dorsal sacroiliac ligament: its implication for understanding low back pain. Spine, 1996. 21(5): p. 556-62.
5. Vleeming, A., et al., Possible role of the long dorsal sacroiliac ligament in women with peripartum pelvic pain. Acta Obstet Gynecol Scand, 2002. 81(5): p. 430-6.