The Sacroiliac (SI) joint is the joint where the spine (the sacrum) attaches to the pelvis (the ileum). SI joint dysfunction is caused by problems at these joints leading to pain and sometimes instability.
The sacroiliac joint is part of the pelvic girdle. This girdle is made up of the two half of your pelvis, your sacrum and the joints where these bones touch - the two sacroiliac joints on either side at the back, and the symphysis pubis joint at the front.
Pelvic Girdle showing the sacroiliac joints and the pubic symphysis
These three bones provide a very strong and stable platform which supports your body weight. The sacroiliac joints in particular are well designed to resist downward pressure. They are very large, ovalish, irregular joints. They are rarely the same on both sides - asymmetry is normal. The irregularity of the joint makes it very firm and stable and there is very little movement that takes place here as a result.
Sacrum showing the large irregular sacroiliac joint surface
The amount and the importance of this small movement is hotly debated. However, I have seen enough people with this problem to know that if this small amount of movement is lost or becomes too great then problems can occur leading to sacroiliac joint pain.
Sacroiliac joint dysfunction can affect anyone at all ages but is mostly caused by the following:.
The most common of all these is pregnancy. This is due to several things:
Sacroiliac joint problems are rarely serious.
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X-ray showing the sacroiliac Joints
X-rays and scans are important if an inflammatory cause of the problem is suspected. They may show up some characteristic changes in the joint such as sacroilitis which is a type of inflammation seen with ankylosing spondylitis.
X-rays may also show any osteoarthritis in the joints- these changes are also called sacroiliac joint arthropathy
If instability is suspected X-rays taken standing on one leg may be suggested.
However, like most lower back pain tests, more often then not scans and X-Rays are normal or just show the usual age changes. .
X-Rays are unsuitable for pregnant women.
However, to diagnose sacroiliac joint pain you don't really need anything that complicated to be honest.
One of the biggest problems with diagnosing this is separating it off from regular non-specific back pain. There are certain physical tests that a clinician can use to work out if the problem is coming from the lower back or the sacroiliac joint. These tests have been recommended in the newest clinical guidelines to help form a diagnosis (Vleeming et al. 2008). Note - several of these tests have to be positive for you to be confident this is the problem.
These are accompanied by a modified Trendeleneberg test and some tests where the clinician feels or palpates the ligaments and joints. Unfortunately, you can't do these to yourself - so you need to go and see someone who can and who will be able to diagnose the problem for you.
This depends on the type of problem and if it is caused by pregnancy:.
A medical or physiotherapy assessment is essential to identify the type of sacroiliac problem and make the right suggestions for managing it.
Vleeming, A. et al., 2008. European guidelines for the diagnosis and treatment of pelvic girdle pain. European spine journal: official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society.
March 2, 2015