SI Joint Pain: What Causes It and How to Treat It

You have been told your back is fine. Your MRI looks normal. But there is a deep, nagging pain on one side of your lower back, right around the beltline, and it will not let up. It gets worse when you stand on one leg, climb stairs or roll over in bed. If that sounds familiar, your sacroiliac joint might be the problem.

The SI joint is one of the most overlooked sources of low back pain. It accounts for an estimated 15 to 30% of all chronic low back pain cases (Simopoulos et al., 2012), yet it is frequently missed because the pain pattern mimics other conditions like disc injuries and sciatica.

Where is the SI joint and what does it do?

You have two sacroiliac joints, one on each side, where your sacrum (the triangular bone at the base of your spine) meets your iliac bones (the large bones of your pelvis). You can usually find them by pressing into the two dimples on either side of your lower back.

Unlike your lumbar spine, the SI joints are not designed for big movements. They allow only a few degrees of motion, but that small amount of give is critical. It acts as a shock absorber between your upper body and your legs. Every time you walk, run or shift your weight from one foot to the other, your SI joints are absorbing and transferring force.

The joint is held together by some of the strongest ligaments in the body. When those ligaments become irritated, stretched or when the joint itself becomes stiff or inflamed, the result is a very specific kind of pain that can be difficult to pin down.

How to tell if it is your SI joint

SI joint pain has a few characteristics that help distinguish it from other causes of low back pain:

One-sided. The pain is almost always on one side, not across the middle of your back. It sits low, around or just below the beltline, and may spread into your buttock or the back of your thigh.
Worse with transitions. Getting out of a chair, getting out of bed or standing up from a bent position tends to aggravate it. The joint is loaded heavily during these movements.
Aggravated by single-leg activities. Climbing stairs, stepping over something or standing on one leg while getting dressed can reproduce the pain because these movements load one SI joint at a time.
Sitting cross-legged or on one side. Asymmetric sitting positions place uneven stress on the SI joints and often make the pain worse.
Rolling over in bed. This is a common complaint. The rotation through the pelvis that happens when you turn over loads the SI joint in a way that can be quite sharp.

The pain can sometimes travel down the leg, which is why it gets confused with sciatica. But SI joint referred pain rarely goes below the knee, and it does not usually come with the numbness or tingling that nerve compression causes.

What causes SI joint pain?

There is usually a combination of factors rather than a single event.

Too much or too little movement. The SI joint can become painful when it is either too stiff (hypomobile) or too loose (hypermobile). Stiffness is more common in men and older adults. Excessive movement is more common in younger women, particularly during and after pregnancy, when hormonal changes loosen the pelvic ligaments.

Muscle imbalances. The muscles around your pelvis work together to stabilise the SI joint. Your glutes, deep core muscles, pelvic floor and hip flexors all play a role. When one group is weak or tight relative to the others, the SI joint takes on load it is not equipped to handle. Weak glutes are probably the most common contributor we see in practice.

Altered movement patterns. If you have been favouring one side because of a knee injury, hip problem or ankle issue, the SI joint on the other side often picks up the extra load. This compensatory pattern can develop gradually and is not always obvious until the pain starts.

Repetitive loading. Running on cambered roads, always carrying a child on the same hip or standing with your weight shifted to one side for hours at a time can all overload one SI joint.

Post-surgical changes. Lumbar spinal fusions, particularly those involving the lower segments, increase stress on the SI joints. A significant proportion of patients who develop adjacent segment problems after fusion go on to develop SI joint dysfunction.

What the research says about treatment

A 2024 meta-analysis published in the Journal of Manual & Manipulative Therapy reviewed 16 randomised controlled trials involving 421 patients with SI joint pain. The results showed that manual therapy was associated with a significant reduction in disability (Trager et al., 2024). The techniques studied included spinal manipulation, joint mobilisation and muscle energy techniques, all of which are part of standard chiropractic care.

A separate 2025 review in the European Journal of Orthopaedic Surgery & Traumatology analysed 38 studies and found that treatment typically progresses from conservative approaches including physiotherapy and lifestyle changes to more invasive options (Migliorini et al., 2025).

The takeaway: hands-on treatment combined with the right exercises works well for SI joint pain.

How we treat it

Treatment starts with figuring out whether the joint is stiff, unstable or a bit of both. That distinction matters because the approach is different for each.

For a stiff SI joint, manipulation and mobilisation help restore normal movement. This often provides significant relief within the first few sessions. We also look at the thoracolumbar junction and hip joints, because restrictions in those areas frequently contribute to SI joint stiffness.

For an unstable SI joint, the focus shifts toward strengthening the muscles that control pelvic stability. Manipulation is used more sparingly, and the emphasis is on progressive loading of the glutes, deep core and pelvic floor. An SI belt can provide temporary support while you build strength.

In both cases, soft tissue work on the surrounding muscles (glutes, piriformis, hip flexors) helps reduce tension and improve how the pelvis moves as a unit.

Exercises that help

These target the muscles that stabilise the SI joint. They are simple but need to be done consistently.

Glute bridges. Lie on your back with your knees bent. Squeeze your glutes and lift your hips until your body forms a straight line from knees to shoulders. Hold for 3 seconds at the top. Start with 3 sets of 10 and progress to single-leg variations as strength improves.

Bird-dogs. On all fours, extend your opposite arm and leg while keeping your pelvis level and your core engaged. Hold for 5 seconds, then switch. This trains the deep stabilisers that support the SI joint during movement. 3 sets of 8 on each side.

Clamshells. Lie on your side with your knees bent. Keeping your feet together, open your top knee like a clamshell. Focus on feeling the work in the side of your hip, not your lower back. 3 sets of 15 on each side.

Side plank (modified). If your SI joint is irritated, a full side plank may be too much initially. Start from your knees and hold for 15 to 20 seconds. Build up gradually. This strengthens the lateral stabilisers that control side-to-side pelvic movement.

When to get it checked out

SI joint pain that has been hanging around for more than a couple of weeks is worth having assessed. It rarely resolves on its own because the underlying cause, whether that is stiffness, instability or muscle imbalance, does not fix itself.

See a professional if:

The pain is affecting your sleep, work or exercise
You are avoiding activities because of the discomfort
The pain refers into your buttock or leg
You have recently had a baby and your pelvic pain is not settling
You have tried stretching and strengthening on your own without improvement

The sooner the cause is identified, the faster the recovery tends to be. Many patients with SI joint dysfunction improve with conservative care over a period of weeks.

If you think your SI joint might be the source of your pain, get in touch or book an appointment. We can work out what is driving it and put together a plan to get you moving properly again.

References

SI JOINT PAIN: WHAT CAUSES IT AND HOW TO TREAT IT