Sacroiliac joint

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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The sacroiliac joint (ISG) or sacrum-iliac joint connects the lower spine with the pelvis. This connection is held by tight ligaments and is very difficult to move, but it can be displaced by poor posture or injuries. Even minimal shifts can lead to pain. Read everything you need to know about the sacroiliac joint!

What is the sacroiliac joint?

The sacroiliac joint (ISG) is the articulated, but almost immobile connection between the lower spine (sacrum = os sacrum) and the two iliac bones (iliac bone = os ilium). So there are two sacroiliac joints in the body. The bumpy joint surfaces are covered with a layer of cartilage. Strong, tight ligament connections only allow minimal tilting or sideways movements, which are important for regulating the width of the pelvis - especially during childbirth. During pregnancy, the ligaments (as well as those of the symphysis pubis) loosen up due to the hormonal change in order to allow the baby's head to pass through during birth.

What is the function of the sacroiliac joint?

The sacrum, as the lower part of the spine, has to transfer the load of the trunk to the two hip bones and further to the legs - the price of walking upright. However, in order to be able to hold the trunk load and not to tip forward into the pelvis, the articulated connection between the sacrum and the two iliac bones - the sacroiliac joint - must be well fixed, which is ensured by strong, tight ligaments. Several such ligaments run from the sacrum to the intestines and ischia. These joint ligaments are reinforced by several smaller ligaments. The sacrum and hip bones form an arch through which the trunk load is transferred to the legs. When walking, there are alternating tiny movements in the two sacroiliac joints. The tight ligaments limit the freedom of movement.

Where is the sacroiliac joint located?

The sacroiliac joint is part of the pelvic girdle. It connects the lower spine (more precisely the sacrum) with the two iliac bones.

What problems can the sacroiliac joint cause?

In the sacroiliac joint (ISG) syndrome, those affected feel pain in the area of ​​the joint, which can also radiate into the lower back and legs. The symptoms increase over the course of the day and are particularly noticeable when lifting loads, straightening up from stooping and standing for long periods of time.

Bechterew's disease (ankylosing spondylitis) is a chronic inflammatory rheumatic joint disease that usually begins in the paired sacroiliac joint. Back pain at night is the early symptom.

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