Understanding the Sacroiliac Joint
Asana Anatomy-Understanding the Sacroiliac Joint
Controversy does not often strike the yoga community. Non-harming, truthfulness, and loving kindness are not very controversial concepts. Yet the poor, barely mobile, sacroiliac joint has become the center of a yoga debate – to square or not to square the hips. Ok, so it is not as racy as a celebrity feud, but it may affect your personal yoga practice.
Let’s dissect this joint.
The two sacroiliac joints (SI joint) are formed by three bones: the triangular sacrum bone, and the two wing like bones of the pelvis known as the ilium. Each iliac bone (one half of the ilium) comes in contact with one side of the sacrum, forming two SI joints. This connection is like three puzzle pieces fitting together known as form closure. Form closure creates stability, keeping the pelvis together in one unit. The SI joint itself is shaped like a boomerang with two arms at 90 degrees to each other. The upper portion lies in an up-and-down orientation and the lower portion lies in a front-to-back orientation. The surface of the joint is covered in coarse cartilage, adding friction and contributing to the force closure.
The sacrum moves in nutation (forward) and counter nutation (backward) in relation to the ilium. The sacrum can move only on one side, like in lifting one leg, or both sides, like when we move from lying to standing. This movement is very small, amounting to 1 or 2 mm of motion in either direction. As we age, the sacrum becomes wedged increasingly forward, but this doesn’t fully happen until we reach our 30’s. This wedging increases the resistance to shearing (twisting) forces across the sacroiliac joint. Herein lies the problem. The SI joint is a joint that is intended to provide stability for the pelvis, and is not built to move.
The SI joint has another mechanism of stability – force closure. This is the stability created by the action of the core musculature that has attachments into the SI joint – namely, the muscles of the pelvic floor, and the transverse abdominis. Conveniently, we can access these muscles through the activation of the bandhas or energy locks in yoga. In mula bandha we imagine a subtle lifting up of the muscles we use to control the flow of urine. In women, activation of this musculature has been shown to provide force closure for the SI joint. In uddiyana bandha, we draw the lower belly in and up, activating the transverse abdominis muscle. For this version, the scooping of the lower belly needs only to be subtle, and slightly flattens out the lower abdomen.
Hip Opening or Sacroiliac Opening?
Many of us identify ourselves as having “tight hips”. For many, this means a lack of external (outward) rotation at the hip joint. Using the example of Virabhadrasana I or Warrior I pose, our front hip is in a flexed position with toes pointing straight ahead. Our back foot is on the floor at a 45 degree angle, and in order for the points of our hips (our iliac crests) to face toward the front of the mat, our back hip needs to extend, and externally rotate. If we look deep inside we see that these actions require our sacrum to nutate forward on the side of the lead leg, and counter nutate backward on the side of the rear leg. If the rear hip resists external rotation in order to square the hip points forward a twisting or shearing force is introduced across the SI joint. Over time this can lead to irritation, hypermobility, and dysfunctional firing patterns of our pelvic musculature.
Happy Sacrum
This situation is an opportunity to practice ahimsa or non-violence towards our SI joints. There are a few ways you can diminish the shearing force across the SI in standing poses. The first is to take a slightly wider stance, opening your feet to hip width (rather than heel to arch or heel to heel). This enables your pelvis to comfortably square forward. Another option is to keep the feet as they are and simply allow your pelvis to be slightly open to the side of your mat. That’s right, let go of the desire to perfectly square your pelvis forward. Instead, imagine the hip bone in its socket, outwardly rotating. Keeping that rotation, tuck the tailbone under slightly, creating room in the front of the hip. You may find that this provides more freedom of movement and may naturally square your hips further. In standing and seated twists, be sure to engage the muscles of the pelvic floor (mula bandha) to support the SI joint before twisting.
When we step back for a moment and acknowledge the true purpose of our yoga practice, suddenly trying to make our bodies fit a mold doesn’t make much sense. Being more forgiving and accepting of our bodies limitations enables us to go much deeper into our yoga practice and experience the joy of yoga safely. Now that doesn’t sound controversial at all.
About the Author
Yoga and Anterior Pelvic Tilt
The anterior pelvic tilt is a hot topic in yoga and in manual medicine. Some people are overly concerned about the fact that their pelvis is tilting anteriorly without even understanding what it means. Let’s simplify the issues behind this increasingly common postural variation and learn how it can affect other parts of our body.
A normal pelvic angle is 30°; this means that our posterior superior iliac spines (the dimples above our bottoms) are slightly higher than our anterior superior iliac spines (the bones that stick out at the front of our pelvis). This angle can vary a few degrees either anteriorly or posteriorly due to our genetic makeup and even temporarily due to tight and/or weak muscles. An anterior pelvic angle of 40° is considered excessive and will produce a lower back (lumbar spine) curve that is also extreme. Our lumbar spine should have an anterior curve which is known as a lordosis; however, when this curve is excessive it is known as a hyperlordosis, which is not ideal. Cases of increased pelvic angles and lumbar hyperlordoses are very prevalent in today’s society.
Causes of increased lumbar lordosis include:
- Postural deformity
- Lax muscles, especially the abdominal muscles in combination with tight muscles, especially hip flexors or lumbar extensors
- A heavy abdomen, resulting from excess weight or pregnancy
- Compensatory mechanisms that result from another deformity, such as an increased curve in the thoracic spine (mid-back)
- Hip flexion contracture
- Spondylolisthesis (displacement of the vertebra above with relation to the vertebra below)
- Congenital problems, such as bilateral congenital dislocation of the hip
- Fashion (e.g., wearing high-heeled shoes)
Magee, J. David. Orthopedic Physical Assessment: Fourth Edition. Saunders. Toronto. 2002.
Cause number two from the list above is the reason that affects most. The majority of the population sits for at least eight hours a day while hunched over a desk at work; this can lead to a generic condition known as lower cross syndrome. This disorder consists of the following muscular issues: Weak or inhibited gluteal muscles and abdominals & Tight and shortened hip flexors and lumbar extensors
To better visualize this, observe the illustration that demonstrates lower cross syndrome. Take note of how the two weak/inhibited muscles create one line of the cross and the two tight/shortened muscles create the other line to complete the shape of a cross, hence lower cross syndrome.
When our hip flexors are tight, specifically our psoas, our pelvis rotates forward by the psoas pulling down on the lumbar spine from its attachment sites; this increases our lumbar lordosis and subsequently shortens our lumbar extensor muscles. This is most often seen in combination with weak abdominal and gluteal muscles.
Now that the reasons for this postural condition have been noted, the way to correct it is clear: reverse the causes. However, the distinction between inhibited muscles and weak muscles must be made first before rehabilitation can effectively begin. Inhibited muscles require the re-establishment of correct muscle firing patterns, while weak muscles need to be strengthened. Some individuals have weak muscles that are not inhibited; some have the reverse, and some have both issues to correct. Tight/shortened muscles require lengthening; sometimes stretching is sufficient and sometimes alternative soft tissue treatments such as Active Release Technique® and Graston Technique® are required to decrease scar tissue and increase the range of motion of the particular muscle.
If you are concerned that you may have lower cross syndrome, or simply a pelvic tilt, paying a visit to your manual health care practitioner (sports focused chiropractor, sports physician) will be well worth the time and money. They will be able to diagnose any underlying issues related to this condition and create an appropriate rehabilitation programs specific to the weaknesses and inhibitions they find upon physical examination. They will also be able to reduce scar tissue that may be contributing to your pelvic tilt (anterior or posterior).
Education is the ticket to eliminating these sorts of conditions from society. If we understand how to mitigate the risks for such generic conditions, we will all be much healthier individuals. Here is to learning more about our bodies!
Learn More about Dr. Carla Cupido.
