Sacroiliac joint pain

What it is

The sacroiliac joints connect the spine to the pelvis and are built for stability rather than movement - they move only a few degrees. Their job is to transfer load between the trunk and the legs, and pain arises when that transfer is poorly controlled rather than when the joint is out of place.

This is why the popular model of a joint that goes out and needs putting back does not hold up. What actually helps is improving the muscular control that compresses and stabilises the joint - the glutes, the deep trunk muscles and the pelvic floor working together.

What it feels like

• Pain low down beside the spine, at the dimple above the buttock, usually on one side
• Worse standing on one leg, climbing stairs and rolling over in bed
• Worse getting in and out of a car
• Sometimes referring into the buttock and the back of the thigh, rarely below the knee
• A sense of the pelvis being unstable or needing to click

What causes it

Most people have more than one of these at once, and they feed each other. Read the list looking for the two or three that sound like your week rather than for the one true answer — the ones that describe you are the ones worth acting on.

Failure of load transfer across the pelvis

The joint is stabilised by compression from the surrounding muscles and ligaments. When that compression is inadequate, load transferring between spine and leg is poorly controlled and the joint becomes painful.

Pregnancy and the postpartum period

Relaxin increases ligament laxity, the growing uterus changes the load and the abdominal wall lengthens. Pelvic girdle pain in and after pregnancy is extremely common and this joint is a major contributor.

Weak glutes and deep trunk muscles

The gluteus maximus and the deep abdominal muscles both contribute to compressing the joint. Weakness in either reduces the stability the joint depends on.

Generalised hypermobility

More elastic ligaments mean less passive stability, so more of the job falls to muscle. Hypermobile people are disproportionately represented among those with this pain.

A fall onto the buttock or a leg length difference

Direct trauma can genuinely injure the joint, and a significant leg length difference changes how load crosses the pelvis with every step.

One-sided habits

Standing hung on one hip, always carrying on the same side, driving with one leg extended for hours. Asymmetric loading over years produces asymmetric symptoms.

Inflammatory sacroiliitis - the different one

Axial spondyloarthritis causes inflammation of these joints and behaves completely differently: worse with rest and in the second half of the night, better with movement, with prolonged morning stiffness. It needs early medical diagnosis and different treatment.

Hip or lumbar problems changing the load

Restricted hip movement or a painful low back changes how force crosses the pelvis, and the sacroiliac joint absorbs the difference.

Fear driven by the out-of-place model

Believing the joint has slipped produces guarding and repeated seeking of manipulation, neither of which builds the stability the joint actually needs.

Who tends to get it

• Pregnant and postpartum women, in whom it is very common
• People with generalised joint hypermobility
• Anyone with weak glutes and deep trunk muscles
• People with a significant leg length difference or an old fall onto the buttock
• Anyone with a history of low back or hip problems

What makes it worse, and what settles it

The qFIT routine for this

Ready-made routineHip Relief & Rotation

qFIT already has this one built. It runs massage first, then stretching, then strength — the order that works on a body that is already sore — and every activity in it carries the reason it is there.

The button below opens your Checklist with this routine already selected, so instead of your whole list you land on just its Categories, Targets and Exercises, each with its checkbox, ready to tick as you work through them.

Have more than one problem? Tick yours under My Problems on My Profile and your Checklist's Routine list gains Recommended for my problems — every routine for the problems you picked, merged into one. Your picks stay private; that filter is the only thing they feed.

Get it checked if…

Bilateral inflammatory back pain in a young adult with morning stiffness over 30 min - screen for axial spondyloarthritis (see the Inflammatory back pain in young adults entry)

And whatever the body part: chest pain or unusual breathlessness on exertion; a fever alongside the pain; unexplained weight loss; pain that is constant and unrelated to how you move; new numbness, weakness or loss of bladder or bowel control; or one calf that is swollen, warm and painful. Any of those, stop and get assessed.

How it usually goes

Strength-based treatment improves symptoms over eight to twelve weeks and the improvement is durable, unlike the short-lived relief from manipulation alone. Pregnancy-related pelvic girdle pain usually improves substantially in the months after delivery, particularly with targeted strengthening. Back pain that is worse with rest, wakes you in the second half of the night and comes with prolonged morning stiffness is a different disease - inflammatory - and early diagnosis genuinely changes the long-term outcome.

Prevalence basis: Diagnostic block studies

Others the same routine covers

These share the Hip Relief & Rotation routine, so the work is the same. If one of them also sounds like you, that is a reason to expect more from it, not less.

This is general information, not a diagnosis, and it cannot examine you. If it matches you, use it to ask better questions of a clinician rather than to replace one.