Asana Anatomy -The Sacroiliac Joint

Stepping your legs wide, bowing gracefully into Prasarita Padottanasana (wide legged forward bend) for the fourth time this class, you finally glimpse the floor close to the top of your head. You finish your yoga practice feeling great, until a slow dull ache develops at the base of your spine, and gradually turns into sharp, shooting pains when you walk.

What happened? You can't recall a specific event, yet yoga is the only thing you did that might have contributed to this mysterious pain. In fact, your beautiful wide legged forward bend may have contributed to you spraining your sacroiliac joint.

Let's dissect this joint.
The two sacroiliac joints (SI joints) are formed by three bones: the triangular sacrum bone at the base of the spine, 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. Like all of the joints of the body, the SI joints are contained by a joint capsule of connective tissue, and bathed in nourishing synovial fluid.

In the front, the joint capsule is covered with the sacroiliac ligament, and in the back the capsule blends with the deep intterosseus ligament. In addition there are more supportive ligaments: the sacrotuberous ligament from the ischial tuberosity (sitting bone) to the sacrum, the sacrospinous ligament which attaches from the ilium and connects to the sacrum, and the iliolumbar ligament with attachments in the lumbar spine and the ilium.

All of these ligaments can provide a lot of support, but also provide the opportunity for injury. To review our anatomy for a moment, ligaments attach bone to bone, and tendons attach muscle to bone. We sprain a joint or ligament, and we strain a muscle or tendon.

Ligaments are meant to be supportive structures, which are generally inflexible. In women who have been pregnant, a hormone called relaxin causes the ligaments to relax to prepare for childbirth, and this effect is global throughout the body. Sometimes this ligamentous freedom can stay, to a smaller degree, after the child is born. In general, women's ligaments are affected by the hormone fluctuations of their menstrual cycles, and have more ligamentous flexibility than males. Interestingly, a number of studies have shown that women who tear their ACL ligament in their knee are more likely to do so when they are ovulating.

The SI joints also gain support from the surrounding musculature. This is a concept known as Force Closure, discussed in a previous article. In particular the muscles of the pelvic floor: pubococcygeus, iliococcygeus, cocygeus, and the core transversus abdominis muscle - which wraps around the lower belly - can be very influential.

Wide Legged Caution
Poses like prasarita padottanasana (wide legged forward bend), baddha konasana (bound angle pose), and upavistha konasana (seated wide legged forward bend) can be a concern for people with a history of SI joint pain, and can predispose the SI joint to injury.

In wide legged forward bend we are simultaneously stretching the adductor muscles of the groin (attachments to the pubic bone) and the hamstring group (with attachments to the sitting bones). When we abduct (move the thigh bones away from midline) the adductor muscles pull on the pubic bones, gapping the SI joint space. This provides more freedom of movement for the SI joint, which may predispose it to moving excessively. The forward flexion component causes the hamstrings to pull on the sitting bones, which in turn stretches the sacrotuberous ligament whose job it is to counter motion in the sacrum. If one hamstring is longer than the other, this can also cause an asymmetrical strain across the SI joints.

One way to support the SI joint in the wide legged poses is to engage the muscles of the pelvic floor and lower abdomen. Studies have shown that contracting these muscles can help stabilize the SI joint by increasing the close fit of the sacrum with the ilium (Force Closure). The pelvic floor is more significant in women, but both men and women can benefit from engaging transversus abdominis. Tips to learn to engage these muscles are described below.

Engaging the Pelvic Floor
Sitting quietly, slow down your breathing. Feel the gentle inhale and exhale creating space and lightness in your body. Bring your attention to the muscles of your pelvis, particularly the muscles you would use to stop the flow of urine. Gently contract these muscles, lifting them up away from the floor. Then gently release. Repeat this action, keeping the natural flow of your breath. Try to contract the muscles closer to the front of your pelvis, rather than the muscles closer to your anus.

Now take this practice onto your mat.

Engaging the lower belly/ Transversus Abdominis
Lying on your back with your knees bent and flat on the floor, slow down your breathing. Notice the gentle rise and fall of your chest and belly as you breathe. Place your hands at your lower belly so that the heel of your hand rests on the bony front of your pelvis (known as the ASIS/Anterior Superior Iliac Spine). Gently draw your belly button in and up so that your lower belly flattens. Breathe normally. Try to keep your large, upper abdominal muscles (rectus abdominis) relaxed. Repeat, breathing normally.

Now take this practice onto your mat.

Mindful Practice
Wide legged yoga poses can be an excellent way to open the muscles of the groin, bring awareness to our root chakra, and release tension in the hamstrings. Much like any asana, when we proceed without being fully present and engaged - physically and mentally- we are at risk for injury. If we are mindful about engaging the muscles that support the SI joints, we are more likely to enjoy a wide legged practice that is safe and pain free.

Dr. Robin Armstrong has combined her decade of experience as both a Chiropractor & Yoga Instructor to develop a unique type of yoga therapy known as Yoga Rehab, blending traditional yoga practices with modern rehab exercise to help students overcome pain and injury. She has shared her knowledge of yoga injury prevention and anatomy with the Canadian Press, American Council of Exercise, Impact, and Alive magazines as well as many local yoga teacher training programs. She practices at YYoga Downtown Flow studio in Vancouver, Canada.

Website: www.stayactive.ca

Facebook: Dr. Robin Armstrong, Chiropractor & Yoga Instructor

Twitter: @DrRobinA

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GIANGEET, posted on September 18, 2011

Beautiful, Thanks a lot for the tips!

shajorah, posted on December 21, 2010

Thank you so very much. This article has been very informative and useful. I am currently in the process of healing a sacral injury. I am not sure when it occurred but I am sure my yoga practice and teaching have contributed to it, unfortunatley. Your advice will be used the next time I head to my mat.

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