By Amber Burke, on Yoga International
For many yoga practitioners, the sacroiliac (SI) joints are shrouded in mystery. Many yoga teachers say that some poses should be practiced in a certain way “for the health of the SI joints” without identifying where these joints are anatomically or explaining why students should care about SI joint health. Even if knowledge of our own bodies has been refined through years of yoga, we still may have only a vague understanding of the sacrum or SI joints, which are located behind our field of vision, at the back of the pelvis, between and above the buttocks. Nor do most of us feel much sensation in this area—at least not until we experience SI dysfunction, with its signal pain, often on one side of the lower back, which often means that we have to alter our yoga practice and and our life.
The sacrum is not only part of the spine, but also the keystone—or connecting wedge—between the spine and the ilia (pelvic bones). A nexus between these two important structures, its Latin appellation is os sacrum, or holy bone. Essentially a continuation of the lumbar spine, the sacrum consists of roughly five vertebrae fused into one rigid, downward-pointing triangular bone whose endpoint is the tailbone, or coccyx. At the junctures to the right and left of the sacrum, where it meets the ilia, are the two sacroiliac joints. Through these joints, much of the weight of the torso is transferred to the pelvis and the legs, and when we walk, these joints help to transmit the force of the impact of our steps upward and diffuse it.
“The SI joint acts as a shock absorber, and it moves slightly as we move to help us maintain our balance and center of gravity,” explains Bill Reif, a physical therapist with 40 years of experience. His book, The Back Pain Secret: The Real Cause of Women’s Back Pain and How to Treat It, focuses on SI dysfunction as an often overlooked cause of back pain and a cascade of other symptoms.
SI dysfunction occurs when the sacrum moves too much or too little for the joint to be able to function—or distribute force—optimally, causing pain. Since around 15 percent of people with lower back pain could be experiencing SI joint pain, it’s been estimated that as many as 10 million Americans suffer from SI dysfunction. That could mean a heavy toll on the quality of life for a huge segment of the population: According to one survey that attempted to quantify the burden of the disease, the condition seems to be more debilitating than asthma and mild heart failure and as debilitating as chronic depression or severe, progressive lung diseases.