What is the SIJ?
The sacroiliac joint or SIJ is where the sacrum (lower part of the spine between the lumbar and the tailbone) joins the ilium (part of the pelvic bone).

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It’s role is in weight bearing, to transfer load from the lower limbs to the spine. Not much movement occurs at the sacroiliac joint because the joint surfaces are made up of irregular bony shapes that fit together like a jigsaw. It is then reinforced further by a system of ligaments and muscles. 

What does sacroiliac joint pain feel like?

Sacroiliac joint pain can be described as dull or sharp. It starts at one or both SI joint at the back of the pelvis, but it can move to your buttocks, thighs, groin, or lower back.

People suffering sacroiliac joint problems will often report pain and difficulty with:
- sitting and/or standing
- moving from sitting to standing
- standing on one leg (eg to put pants on)
- walking, jumping, jogging
- rolling in bed
- getting in and out of the car
- driving

What causes pain at the sacroiliac joint?
The cause of sacroiliac join pain is likely to be multifactorial and may be different in different people. Factors such as hormonal changes, biomechanical, traumatic and degenerative changes are potential contributing factors 
Research has also shown that negative body perception and fear of pain and movement may also play a role.

Why is pain so common in this area during pregnancy?
It was originally thought that the hormone Relaxin was responsible for increased joint laxity and sacroiliac joint pain during pregnancy. Multiple studies however have found that there is no link between Relaxin levels and pelvic girdle pain or disability. 

During pregnancy Estrogen levels increase significantly and it has actually been found that the strength of connective tissue and ligaments decreases in the presence of oestrogen. However, a strong correlation between estrogen levels and sacroiliac joint pain has not yet been established either. 

The cause is probably a combination of increased connective tissue laxity, biomechanical dysfunctions and a baby getting bigger and placing more stretch and load on the pelvic floor, abdominal muscles and pelvic ligaments .

What can physio treatment do?
It’s not a one size fits all solution.  If the load transfer through the sacroiliac joint is non optimal and contributing to pain, physio can help assess and address the biomechanical contributing factors. Treatment may involved releasing the tight muscles or strengthening the deep stabilising muscle groups such as the core and deep gluteals. These muscle groups assist in the stability around the sacroiliac joint and weakness may contribute to pain and dysfunction. Any cognitive and emotional contributory factors also need to be discussed.

Some of the cognitive contributing factors include:
- Poor belief patterns around pain
- bad lifestyle habits
- fear around movement
- stress and anxiety
- Lack of coping mechanisms
- Boom-bust type activity levels
- Lack of support

Sacroiliac joint pain can get worse and lead to further dysfunctions if left untreated. For this reason, if you are experiencing sacroiliac joint pain book in to see a physio to get on top of it as soon as possible.