A deep ache low in your back, just to one side, that can spread into your buttock or the back of your thigh. Standing on one leg to put on your trousers, rolling over in bed or getting out of the car can bring it on. Sacroiliac joint pain can be uncomfortable and confusing, but understanding it can help you find more comfortable ways to move.

What the sacroiliac joint is

You have two sacroiliac joints, one on each side, where the base of your spine meets your pelvis. They sit roughly under the two dimples at the bottom of your back. These joints only move a tiny amount, but they play an important role in passing weight between your upper body and your legs.

Strong ligaments and muscles surround the joints and keep them stable. When the joint or the tissues around it become sensitive, pain can be felt low in the back, in the buttock and sometimes down the back of the thigh.

Where the pain comes from

Sacroiliac joint pain can develop for different reasons:

• A fall or jolt, like landing heavily or missing a step.
• Repeated load on one side, like standing with your weight on one leg.
• Changes during and after pregnancy, when hormones soften the ligaments around the pelvis.
• Differences in how you walk or move, sometimes linked to other pain.

You may have heard that the joint has slipped or is out of place. Although it can feel that way, research suggests the joint does not usually slip out of position. Pain usually comes from the joint and surrounding tissues being sensitive, which responds well to the right movement and strength.

Sitting more comfortably

Some changes that can help when sitting:

• Sit with your weight even on both sides, rather than leaning to one.
• Keep your feet flat on the floor and avoid crossing your legs.
• Use a cushion if your chair feels hard.
• Get up and move every half hour or so.

VIDA’s Pomodoro stretches, in the top right corner, can prompt you to pause and move during focused work.

Standing more comfortably

When standing, try sharing your weight between both feet, rather than resting on one hip. Some everyday changes can help too:

• Sit down to put on trousers, socks and shoes.
• Getting into the car, sit down first, then swing both legs in together.
• When turning over in bed, keep your knees together and roll your body as one.
• Take stairs one at a time if they bring on pain.

Movements that help

Gentle movement can ease stiffness around the joint. Something to try a few times a day:

• Lying on your back with your knees bent, gently rock both knees from side to side.
• Lying on your back, hug one knee towards your chest, then swap.
• On your hands and knees on the floor, slowly round your back up, then let it gently dip down.

If a movement brings on sharp pain, make it smaller or leave it out. If you would like a guided stretch, VIDA has short videos you can follow at your own pace.

Building strength

Strengthening the muscles around your hips, buttocks and trunk helps support the sacroiliac joints. Something to try two or three times a week:

• Bridges. Lie on your back with your knees bent, lift your hips, then lower slowly.
• Sit to stand. Rise from a chair without using your hands, then lower slowly.
• Side-lying leg lifts. Lie on your side with a pillow between your knees and slowly lift your top knee a little way, keeping your feet together.

If you would like to follow along, VIDA has short videos of bridges and sit to stands you can use at your own pace. Start with a few repetitions and build up. If you have been given exercises by a physiotherapist, keep following those.

Staying active

Walking, swimming and cycling are good ways to stay active. Shorter walks on flat ground often feel easier at first. Building up gradually helps.

When to get it checked

If your back and buttock pain is often worse at night or first thing, with morning stiffness that lasts more than half an hour and eases as you move, it is worth speaking to your GP.

Your VIDA pain check-in can help you notice which activities help and which bring on pain.

What to take away

• Sacroiliac joint pain usually comes from sensitive tissues, not a joint that has slipped.
• Sit and stand with your weight even on both sides.
• Keep your knees together when getting into the car or turning in bed.
• Try gentle movements to ease stiffness.
• Build hip and trunk strength two or three times a week.

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