Sacroiliac Joint Pain (SI Joint): How to Recognise and Treat It

The sacroiliac joint is a relatively immobile joint surrounded by a very strong ligamentous and muscular apparatus. Its job is to transmit loads between the trunk and the lower limbs and to cushion the forces acting on the pelvis during walking. Pain may arise from the joint itself (inflammatory or degenerative changes, irritation of the capsule) and from the surrounding ligaments, muscles and fascia.

The consensus guidelines use the term 'sacroiliac joint complex' because the source of pain may be intra-articular as well as extra-articular structures (the posterior ligaments, the capsule, the fascia). The committee found that the prevalence of intra- and extra-articular pain is comparable, and that the distinction matters for choosing treatment. Factors mentioned in the literature include injuries, pregnancy and childbirth (loosening of ligaments and increased load), gait disturbance and leg length difference, previous spine surgery and inflammatory joint disease.

Why is diagnosis difficult? Because SIJ pain overlaps with pain arising from the lumbar spine, the hip joint and the gluteal muscles, and symptoms can be similar. There is no single infallible feature, and imaging (MRI, CT) does not settle the matter — according to the guidelines, the evidence for the usefulness of imaging is unclear or negative.

Typical SIJ pain is one-sided, located in the buttock and lower back, sometimes radiating to the groin, thigh or, less often, below the knee (without the dermatomal distribution typical of sciatica). Patients can often point with one finger to the place of greatest tenderness just below and medial to the posterior superior iliac spine. The pain worsens with prolonged standing, sitting, climbing stairs, changing position and turning over in bed.

The table is a guide: in many people the pain is mixed, and the doctor takes the whole picture into account. Note the last row — inflammatory pain has different features from mechanical pain, as we describe further on.

There is no single physical test that reliably confirms SIJ pain. Instead, sets of provocation tests are used, that is manoeuvres that load the joint and are meant to reproduce the patient's 'familiar' pain (including the thigh thrust test, posterior shear, pelvic compression and distraction, and Gaenslen's test). The reference point in studies is a diagnostic block, that is an injection of local anaesthetic into the joint under imaging guidance.

The result is useful, but its limits must be known. The study was small (48 people), and the reference was an anaesthetic block, which itself has limitations — the result depends on the technique, the drug used and the threshold of relief adopted. Test results should therefore be treated as grounds for suspicion, not proof.

The systematic review by Szadek et al. (Journal of Pain, 2009; 18 studies) confirms that sets of tests have some discriminative value: for the thigh thrust test the diagnostic odds ratio was 18.461 (95% CI 5.82–58.53), for the compression test 3.88 (1.7–8.9) and for three or more positive provocation tests 17.16 (7.6–39). The authors caution, however, that because a true gold standard for the diagnosis of SIJ pain is lacking, the validity of these tests should be judged carefully, and block techniques and criteria differed between studies. The 2025 consensus guidelines add: the set of tests has reasonable sensitivity but lower specificity for intra-articular (not extra-articular) pathology, and negative results have greater predictive value than positive ones.

Usually not in a decisive way. X-ray, CT and MRI may show degenerative or inflammatory changes in the sacroiliac joint, but the changes themselves do not prove that they are the source of pain — as in other parts of the spine, abnormalities on imaging are also found in people without complaints. The 2025 consensus guidelines rate the evidence for the usefulness of imaging in diagnosing SIJ pain as unclear or negative.

Imaging does, however, have an important role in excluding other diseases: fracture, infection, cancer and inflammatory disease of the sacroiliac joints (axial spondyloarthritis), as well as lumbar disc or hip changes as alternative causes. According to the European guidelines on pelvic girdle pain (Vleeming et al., 2008) MRI may be used to exclude ankylosing spondylitis and when warning signs are present, whereas routine X-ray, CT and scintigraphy are not recommended for diagnosing pelvic girdle pain. We write about the possibilities and limits of MRI in our knowledge base.

Let us begin with an inconvenient truth: the evidence for the effectiveness of non-pharmacological treatment of SIJ pain is largely indirect. The 2025 consensus guidelines state that the evidence base for non-interventional therapies is indirect and mostly extrapolated from studies of lower back pain. This does not mean that exercise and physiotherapy are useless, but that we do not have good SIJ-specific studies of effectiveness.

What follows? Manual therapy seems to improve functional ability, whereas its effect on pain itself is uncertain, and it is not known whether it is better than exercise. It is therefore sensible to combine short-term manual techniques (if they bring relief) with exercises for pelvic stabilisation, strengthening of the gluteal and trunk muscles, and regular activity. We discuss the general principles of gradually increasing load in the article on exercise in chronic lower back pain and in our entry on strength training.

Painkillers and anti-inflammatory drugs (for example non-steroidal anti-inflammatory drugs) may briefly reduce pain and make movement easier, but their choice and duration should be decided by a doctor, especially in heart or kidney disease, ulcers or when taking anticoagulants. Pelvic belts and braces are used on occasion, but we found no reliable data on their effectiveness in the sources we checked, so we make no recommendations.

Three conclusions matter for the reader. First, steroid injections may give relief lasting at least several weeks in well-selected patients, but the relief is often short-lived and not certain. Second, radiofrequency ablation of the lateral branches has the strongest evidence for the duration of relief (at least 6 months), but concerns a precisely selected group of patients (after successful blocks). Third, procedures such as prolotherapy, platelet-rich plasma and joint fusion have weak or very weak evidence and should be considered only after simpler options have been exhausted.

The guidelines also point to the lack of standardisation of diagnosis and treatment, which means that management in individual centres may differ. It is therefore worth asking the doctor: on what basis was SIJ pain diagnosed, what are the alternatives, what are realistic expectations for the length of relief and what risk does the procedure carry. We do not describe the availability or cost of procedures in any country.

Pelvic girdle pain (PGP), which also includes complaints in the region of the sacroiliac joints, is common in pregnancy. According to the European guidelines (Vleeming et al., 2008) the proportion of pregnant women suffering from PGP is about 20%; the risk factors in pregnancy most probably include previous lower back pain and previous pelvic trauma, while factors considered probably not to increase risk include oral contraceptives, the interval since the last pregnancy, height, weight and smoking. Diagnosis rests on pain provocation tests and palpation tests and on the active straight leg raise (ASLR) test as a functional test.

The guidelines recommend adequate information and reassurance for the patient and individually tailored exercises in pregnancy, and for other patients an individualised multifactorial treatment programme. Pelvic girdle pain in pregnancy and after childbirth calls for a conversation with the doctor in charge or a women's health physiotherapist; drugs and methods are chosen with the safety of the baby in mind. It should be remembered that PGP in pregnancy and sacroiliac joint pain in other situations are not identical, although symptoms can be similar.

Inflammatory disease of the sacroiliac joints (sacroiliitis in axial spondyloarthritis, including ankylosing spondylitis) produces pain that differs from mechanical pain. Experts of the ASAS society, analysing real patients, identified five parameters that best explained the inflammatory nature of back pain; among them were improvement with exercise (odds ratio 23.1), night pain and no improvement with rest. When at least four of the five parameters were met, the criteria had a sensitivity of 77.0% and specificity of 91.7% in the workshop group and 79.6% and 72.4% in the validation group (648 patients).

In practice this means that lower back and buttock pain that began in a young person (usually before the age of 40), worsens at night or in the early morning, is accompanied by morning stiffness and improves with movement rather than rest should prompt a consultation with a rheumatologist. Diagnosis rests on the history, blood tests (including markers of inflammation), imaging (MRI of the sacroiliac joints) and specialist assessment. Such pain should not be treated like typical mechanical pain.

In most cases the first and best-justified step is an active exercise programme with physiotherapy. Invasive methods are worth considering only when the pain is resistant and the diagnosis has been reliably confirmed, that is after discussion with a specialist.

See a doctor (within days to weeks) also when the pain lasts longer than a few weeks despite movement and simple measures, limits walking or sleep, or when you are unsure of the cause. The doctor will assess whether imaging, a rheumatological or orthopaedic consultation or referral to a physiotherapist is needed.

Sacroiliac joint pain is a common but diagnostically difficult source of chronic lower back pain. The best approach combines a careful history and examination with an honest assessment of the limits of the evidence: no single test or imaging study settles the matter, and the effectiveness of many treatments is poorly documented. It is therefore sensible to start with activity and physiotherapy and to use invasive interventions after reliable confirmation of the diagnosis.