Where the sacroiliac joint is and when it hurts
The sacroiliac joint connects the sacrum to the wing of the ilium – there is one on each side, roughly where two dimples can be seen on the back above the buttocks. It is a strong joint, held together by powerful ligaments, and it moves through a very small range. Its job is to transfer load between the trunk and the legs when walking, running or climbing stairs.
Pain from this area is usually one-sided: patients point to it with one finger right next to the sacrum, and it radiates into the buttock and the back of the thigh. It appears most often in pregnancy and after giving birth, in runners and people who train with a clear dominance of one leg, and after injuries – a fall onto the buttock or an unexpected step off a kerb.
How we tell this pain apart from the spine and the hip
The sacroiliac joint lies right next to the lumbar spine and the hip joint, and symptoms from these three places can be deceptively similar. That is why we start with the spine: we check lumbar mobility and the response to repeated movements, do a neurological examination, and then check the hip’s range of motion.
Next we carry out provocation tests that load the joint from different directions – the so-called Laslett cluster. To be honest, no single test identifies a problem with this joint. Only several positive tests (usually at least three), with pain from the spine ruled out, clearly increase the likelihood that the joint is the source of the symptoms. It is still an assessment of probability, not certainty – and that is how we treat it.
In the history we also look for features of inflammatory pain. If the symptoms started before the age of 45, wake you at night, your back is stiff for more than half an hour in the morning, and movement helps more than rest, this may point to an inflammatory joint disease of the spine (spondyloarthropathy). We then refer you to a doctor or a rheumatologist – this kind of pain needs investigation and treatment that physiotherapy cannot replace.
What helps – and what we do not promise
The popular idea of “putting the pelvis back in place” has no support in research. The joint moves minimally – by a few degrees and millimetres – and manual techniques do not change its position. They can, however, reduce pain and tension in the area – and that is what we use them for, as a lead-in to exercise rather than a treatment in its own right.
The foundation is training: strengthening the glutes, trunk and hips, pelvic control when standing on one leg, and a gradual increase in load. When the pain is more severe, it helps to limit for a while the movements that trigger it, such as asymmetric lifting or wide lunges. We run the exercises as part of medical training, and the choice of exercises follows from the assessment. With longer-standing symptoms, the realistic timeframe is usually from a few weeks to three months.
Pregnancy, running and getting back to activity
Pelvic girdle pain in pregnancy is common, and in most women it settles within a few months after giving birth. During this time adapted exercises help, as do changing the way you get out of bed and into the car, and for some women a pelvic support belt worn when needed. If the pain persists long after giving birth, it is worth having it assessed – it can usually be reduced considerably.
With runners we return to training gradually: first walk-run sessions on flat ground, then longer stretches, hills and jumps, always checking the response over the following 24 hours. If the pain travels below the knee or is felt deep in the buttock, we also check for piriformis syndrome and sciatica. You can arrange an appointment via the Contact page.