Sacroiliac Joint

Sacroiliac Joint Derangement

What It Is

As far as I know, sacroiliac joint derangement is the most commonly underdiagnosed cause of low back pain. One reason is that this condition doesn’t show up on X rays, MRIs, or EMGs.

We humans are prone to sacroiliac joint derangement because the entire spine and all its related structures rest on the spade-shaped sacrum, a midline bone which comes to a point where the coccyx begins. The sacrum is connected on both sides to the iliac bones, forming the right and left sacroiliac joints. The whole weight of the body above the waist is supported by those two joints.

anatomy of the sacrum

In much of the animal kingdom, from the elephant to the mole, joints that must bear heavy weights are horizontal, like the top of a table. The knee and ankle are examples. But because we stand erect our sacroiliac joints are nearly vertical. In an engineering sense this isn’t ideal. All the weight in the upper body, all our twists and moves, must be supported by these vertical joints, which routinely withstand tremendous forces but also can slip out of alignment rather easily.

By far the most likely cause of injury to our bones in general and our sacroiliac joints in particular is the stress we put on them with our activities. Our daily struggles with our environment that cause us to run, stop short, pull, push, lift, and so forth, put much more strain on us than gravity does.

The three-dimensional structure of the sacroiliac joint is very complex and irregular (the following image). Its normal range of motion is so small it must be measured in millimeters. You can think of the sacroiliac joint as a complicated three-dimensional jigsaw puzzle with numerous notches and tabs that must fit exactly into one another. When the pieces don’t match up perfectly, the result can be extremely painful.

An inner view of the left sacroiliac joint. If the joint on one side of the sacrum is in poor alignment, the other side must be too.
An inner view of the left sacroiliac joint. If the joint on one side of the sacrum is in poor alignment, the other side must be too.

Pushing any one part of this intricate structure beyond its normal range of motion might redistribute all the weight it bears, concentrating the weight on one tiny irregularity in the wall of the joint. That can be extremely painful until one changes position. If the angle or tilt of one side of the sacroiliac joint shifts, the patient may experience short bursts of pain on the other side. The pain usually occurs along the margins of the joint, but is sometimes so severe that it spreads to the hip or the abdomen or results in sciatica. Pressing on the joint usually hurts, at least to a degree. Sacroiliac joint derangement can cause all kinds of neck and back problems and frequently coexists with piriformis syndrome.

sacroiliac ligament


Think of recent events in your life that involved lugging heavy objects, posture-changing, emotional stress, or an accident involving feet or pelvis during exercise or dancing. A discrete, relatively minor, vertical trauma can cause sacroiliac joint derangement—for example, walking down the street and stepping in a pothole. Differing leg lengths can cause and also result from it.

Symptoms and Signs

Like spinal stenosis (and unlike radiculopathy), the pain from this condition can change from side to side. Characteristically the grinding or gnawing ache worsens with certain movements, such as lifting the feet when getting into or out of a car, reaching up while standing, bending down while knees are locked, and getting out of bed in the morning. Twisting to one side will hurt more than twisting to the other. This pain occurs below the of the back, where people used to talk about feeling lumbago. The pain occasionally can radiate down the leg, like sciatica, but lacks the objective signs of nerve involvement. Shifting your weight usually helps a little but doesn’t alleviate the pain for long.

sacroiliac pain

Look for pain that can get worse all of a sudden at any time of the day. One leg might feel shorter than the other. You can find it difficult to spread your legs apart.

Self-Examination If  lying down on your back with one leg hanging off the bed causes pain in this joint, you are probably suffering from SI derangement (the following image).

If it hurts below the small of your back when your leg hangs off the bed, you have sacroiliac joint derangement.
If it hurts below the small of your back when your leg hangs off the bed, you have sacroiliac joint derangement. Carefully try the test on both sides.

What  It’s Not

With sacroiliac joint derangement, there aren’t any neurological signs: no numbness, weakness, or change in reflexes. A patient rarely experiences sensations of hot and cold, or tingling. If the pain hasn’t been bad all day, it’s unlikely that it will wake you in the night.

Cautionary Note

The pain of sacroiliac joint derangement is always in the lower back, but some patients mistakenly think it’s in their hips. Failure to look for this problem is a usual cause of the failure to diagnose it. If the derangement is relatively new, it can be cured quickly.

What To Do

Unfortunately, standard diagnostic tests don’t show sacroiliac joint derangement, but they can be helpful in ruling out other problems. An MRI of the lumbar and sacral regions of the spine can rule out a fracture, herniated disc, and spinal stenosis. EMGs, bone scans, myelograms, and gallium scans are usually of little use. Abscesses due to tuberculosis and other infectious diseases can reach the sacroiliac region and mimic derangement.

What you need is a physician who can recognize this problem through a complete set of hands-on tests. In one of these relatively simple tests the physician places his or her thumbs on the patient’s pelvic bones just above and beside the sacrum. When the patient bends forward, in standing and sitting positions, the doctor can feel the derangement.

I recommend an osteopath who is willing to work with you by using actual physical manipulation. Physiatrists and physical therapists are next on my list as sources of help. Strain/counterstrain techniques used in manual medicine, muscle energy techniques, and methods of intentional muscle fatigue can bypass the usual fixed rigidity caused by bone displacement and open up the possibility of manipulation, which can put the joint in its proper place.

Surgery is done, but only in cases of severe derangement or severe fracture.

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