Sacroiliac joint pain: a frequently overlooked cause of back and buttock pain
Think sacroiliac joint pain may be causing your symptoms?
The myBackPain assessment identifies the SIJ pattern from your answers — and distinguishes it from lumbar spine causes and sciatica. Results in minutes.
What is the sacroiliac joint?
The sacroiliac joints — there are two, one on each side — connect the sacrum (the triangular bone at the base of the spine) to the iliac bones of the pelvis. They are weight-bearing joints with limited but important movement, reinforced by some of the strongest ligaments in the body.
Image: Wikimedia Commons / CC BY-SA 4.0
When the sacroiliac joints are not functioning correctly — either through too much movement, too little, or inflammatory change — they can be a significant and persistent source of lower back and buttock pain. SIJ dysfunction is both commonly present and frequently overlooked as a primary diagnosis. Many people with SIJ pain spend years being treated for lumbar spine conditions without meaningful improvement, because the sacroiliac joint was never properly assessed.
What does SIJ pain feel like?
- Pain in the lower back, buttock, and posterior upper thigh — rarely travelling below the knee
- Pain that is typically on one side, though it can alternate between sides
- Worse with prolonged sitting, standing on one leg, rolling over in bed, and ascending stairs
- A catching sensation or sharp pain when transitioning from sitting to standing
- In pregnancy and after birth: pain specifically at the back of the pelvis, worse with walking and single-leg weight-bearing
- Pain that may be provoked by specific clinical tests — the joint is deep and not directly accessible to palpation
SIJ referral pain travels into the buttock and posterior thigh, following a similar path to L5/S1 sciatica. Without careful assessment, the two can be indistinguishable from symptoms alone. The key difference: true sciatica typically travels below the knee with specific neurological features (numbness, tingling, weakness), whereas SIJ referral usually stays above the knee and has no neurological component. The myBackPain assessment captures this distinction specifically.
What causes SIJ dysfunction?
How is it identified?
No single test reliably diagnoses SIJ dysfunction. A cluster of positive provocation tests combined with a clinical history consistent with SIJ involvement provides the best diagnostic accuracy. MRI can show sacroiliitis (inflammatory change at the joint) but does not reliably show mechanical SIJ dysfunction — a normal MRI does not rule out SIJ pain as the source.
This is one of the reasons SIJ dysfunction is so frequently missed — patients are told their scan is normal and therefore the SIJ cannot be the problem. This is incorrect. The diagnosis is primarily clinical.
The assessment captures the SIJ pattern specifically — the asymmetric loading aggravation, the rolling over in bed symptom, the buttock-dominant location without below-knee radiation, and the specific causes including pregnancy, postpartum, and leg length discrepancy. It also distinguishes mechanical SIJ dysfunction from inflammatory sacroiliitis.
What helps?
Manual therapy
Specific SIJ mobilisation and manipulation is the primary treatment for mechanical dysfunction. Osteopaths, chiropractors, and physiotherapists all use SIJ-specific techniques effectively. The joint responds well to targeted hands-on treatment once correctly identified.
Exercise rehabilitation
Pelvic stability exercises, gluteal strengthening, and hip mobilisation address the underlying movement dysfunction that often maintains SIJ irritation. Exercise prescription from a practitioner familiar with SIJ mechanics is significantly more effective than generic advice.
SIJ belt
In pregnancy and postpartum, a sacroiliac belt compresses the pelvis and significantly reduces pain by providing external stability to the hypermobile joint. It can be worn during activity and provides immediate relief for many women.
Steroid injection
A fluoroscopically guided SIJ injection can provide significant pain relief for inflammatory or refractory cases. Also useful as a diagnostic tool — if the injection relieves symptoms, the SIJ is confirmed as the primary source.
Self-management
- Avoid asymmetric loading — carry bags on alternating sides, avoid prolonged single-leg standing
- Sleep with a pillow between the knees in side lying to reduce rotational strain at the pelvis
- When getting out of bed, keep the knees together and roll onto your side before pushing up
- Avoid activities that require repeated single-leg weight-bearing in the acute phase
For chronic SIJ pain that has not responded to other management, radiofrequency ablation of the lateral branches supplying the joint is an option. This provides longer-term pain relief and is appropriate where conservative management has been well-conducted and pain remains limiting.
PDF — a printable summary to share with your GP or practitioner
Not sure if sacroiliac joint pain is causing your symptoms?
The myBackPain assessment identifies the SIJ pattern from your specific answers — and distinguishes it from lumbar spine and sciatica presentations that are often confused with SIJ pain.