The Sacroiliac joint is a controversial one. Some people maintain that it only moves in childbirth, but success in treating it has led me to believe that it does move a very small amount in the general population. Like any other joint that moves, it can be irritated, but I have yet to see evidence that it routinely gets stuck in a twisted position.
The SIJ is the joint between your spine (specifically the sacrum) and the pelvis (specifically the ilium). You might have dimples over the area, or you might just be able to feel the bony end of the ilium. It usually isn’t tender, even if the joint is irritated.
Unlike a hip or shoulder, the SIJ is a plane joint- it has little range of movement, but when this movement is out of balance, even the force of your foot hitting the pavement can be painful. The pain may occur in the restricted joint or the other side where it’s compensating. Part of the treatment is working out which side is causing the problem.
Referred pain is quite common when the SIJ is irritated. Research by Jung et al has highlighted a number of areas that can be involved in this process- shown in the diagram above. This isn’t to say that all or any of the areas may be painful, but it’s important to note that the pain can track down the back of the leg. It’s not uncommon for sacroiliac joint problems to be mistaken for sciatica, but rather than a nerve being irritated directly, it’s a misinterpretation of the pain by the brain. If the nerve that supplies the joint detects pain, the brain is not always sure where it’s coming from within the area that the nerve supplies. For more information on that, watch this video.
We can all agree that the SIJ moves in pregnancy and childbirth, as the hormone changes cause the ligaments to become more lax. This can be a direct cause of sacroiliac pain, even the hormone fluctuations through the normal monthly cycle can be enough to irritate the joint. Noticing patterns like this can help with your diagnosis and treatment, so don’t be afraid to let your osteopath know!
Depending on the factors leading to the pain, SIJ problems can resolve quickly or need a longer course of treatment. For most people, the SIJ doesn’t click like a spinal joint, but sometimes a strong articulation can cause a “clunk” feeling or sound. Exercises to help keep the joints mobile between treatments include single legged knee hugs or opening and closing the gate.