If you have a nagging pain low down on one side of your back or deep in the buttock, it is easy to assume it must be a disc or a general back problem. But one-sided low back or buttock pain often comes from a spot most people have never heard of, the sacroiliac joint, where the base of the spine meets the pelvis.
The reassuring part is that most people with sacroiliac joint pain improve with physiotherapy and exercise rather than injections or surgery. Here is what the sacroiliac joint is, why it can become painful, what tends to help, and when it is worth getting assessed.
In this article
What is the sacroiliac joint?
You have two sacroiliac joints, one on each side, and they sit low down where the base of your spine, the sacrum, meets the pelvis. They are strong, stable joints held together by thick ligaments, and their job is to transfer load between your spine and your legs every time you stand, walk or lift.
Because they sit so low in the back and close to the buttock, pain from these joints is often felt on one side, over the dimple at the base of the spine or deep in the buttock. It is a recognised source of low back and buttock pain, and it is more common than many people expect.
Why does the SI joint become painful?
Sacroiliac joint pain usually comes from the joint and its surrounding ligaments being irritated or loaded in a way they are not used to. There is often no single dramatic cause. Common contributors include:
- A change in load, such as a new job, more lifting, or a sudden increase in training
- Pregnancy and the period after birth, when hormones and changing load affect the pelvis
- Long periods of sitting, driving or standing on one leg
- A slip, trip or awkward landing that jars the pelvis
- Uneven loading through the hips and pelvis over time
For over-30 desk workers and busy parents, it is often the everyday combination of prolonged sitting and lifting that tips a sensitive joint over.
What does SI joint pain feel like?
The typical picture is pain on one side of the low back or buttock, often described as deep, dull or aching, sometimes sharp with certain movements. People often notice:
- Pain low on one side of the back or in the buttock, often near the dimple at the base of the spine
- Discomfort that can spread into the back of the hip or upper thigh
- Pain that flares with rolling in bed, getting out of a car, standing from sitting, or standing on one leg
- An achy, tired feeling after long periods of sitting or standing
Symptoms are usually one-sided, which is one of the clues that the sacroiliac joint may be involved rather than a general back strain.
Is my pain the disc or the SI joint?
This is one of the most useful questions to answer, because the two can feel similar but are managed a little differently. Disc-related pain often sits more centrally in the low back and can travel down the leg past the knee, sometimes with pins and needles. Sacroiliac joint pain tends to stay lower and to one side, over the buttock and around the base of the spine.
This is also where the numbers surprise people. Reviews estimate the sacroiliac joint is responsible for a meaningful share of chronic low back pain, so it is well worth considering rather than assuming every low back problem is a disc.
Managed without surgery for most
Most people with sacroiliac joint pain are managed well with physiotherapy and exercise rather than injections or surgery, which is a reassuring starting point.
What helps sacroiliac joint pain?
The good news is that many people improve with practical, non-surgical care. A typical plan focuses on calming the joint, then building control and strength around the pelvis so it can handle load again. This often includes:
- A clear assessment to confirm the sacroiliac joint is the likely source and rule out other causes
- Gentle movement and pelvic-control exercises to settle symptoms and build support around the joint
- Progressive strengthening for the hips, glutes and trunk to share load more evenly
- Practical changes to sitting, standing and lifting habits that keep aggravating the joint
- Advice on staying active in a way that helps rather than flares things up
A physiotherapist can tailor this to you, so the exercises match your stage and your goals rather than a generic routine. If you would like guidance, our team offers physiotherapy in Mount Gravatt for people across Brisbane's southside.
When should you seek help?
Consider getting assessed if
You have one-sided low back or buttock pain that is not settling, pain that keeps returning, or pain that is limiting your work, sleep or activity. It is also worth seeing your doctor promptly if you have pain after a significant fall, unexplained weight loss, fever, or any loss of bladder or bowel control, so more serious causes can be ruled out and your plan can be tailored to you.
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Helping You Perform at Your Best
At ACE Sports Medicine in Upper Mount Gravatt, our physiotherapists provide personalised care for sacroiliac joint and low back pain for people across Brisbane's southside. Your first appointment includes an assessment and a plan matched to your stage, so you can move with more confidence.