Sacroiliac Joint Pain: Is Your Back Pain Actually Coming From Your SI Joint?
Pain near the dimples of your lower back?
Discomfort while climbing stairs, turning in bed, standing on one leg or getting up from a chair? The problem may not always be your spine. Sometimes, the sacroiliac (SI) joint deserves attention.
Lower back pain is one of the most common reasons people seek medical advice. Many patients assume that every episode of back pain must be due to a slipped disc, lumbar spondylosis or sciatica. But there is another possible source of pain that often goes unrecognised: the sacroiliac joint.
The challenge? SI joint pain can look remarkably similar to other causes of lower back pain. And treating the wrong structure may lead to months of frustration, unnecessary investigations and treatments that fail to address the real problem.
The good news is that a careful clinical assessment can help identify whether the SI joint is contributing to the pain—and guide an appropriate treatment plan.
What is the sacroiliac joint?
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The sacroiliac joints connect the sacrum—the triangular bone at the base of the spine—to the ilium, part of each side of the pelvis.
There is one SI joint on each side. These joints have strong ligaments and allow only a small amount of movement. Their job is important: they help transfer loads between the trunk and the legs during standing, walking and other everyday activities.
When pain arises from this region, it may be related to the joint surfaces, surrounding ligaments or nearby structures. However, pain in the SI joint area does not automatically mean the SI joint itself is responsible.
That distinction matters.
Why does SI joint pain develop?
There is rarely one explanation for every patient. Sacroiliac joint pain may develop when the joint or its supporting ligaments become painful or overloaded.
Common contributing factors include:
Pregnancy and the postpartum period: Hormonal changes and altered load transfer may contribute to pelvic girdle pain.
Prolonged standing or repetitive loading: Particularly when combined with poor load tolerance or sudden changes in activity.
Trauma: A fall onto the buttocks, road traffic injury or other pelvic trauma.
Previous lumbar spine surgery: Particularly spinal fusion, which may alter forces transmitted through the pelvis.
Inflammatory arthritis: Conditions such as axial spondyloarthritis can affect the sacroiliac joints.
Reduced strength or movement confidence: Deconditioning and altered movement patterns may contribute to persistent symptoms in some people.
Importantly, pain around the SI joint does not always indicate a joint that is “out of alignment.” The diagnosis requires assessment of the person's symptoms and examination findings.
What does sacroiliac joint pain feel like?
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Patients commonly describe:
Pain on one side of the lower back, below the belt line.
Discomfort near the small bony prominence at the back of the pelvis.
Pain spreading into the buttock, and sometimes the thigh.
Pain while climbing stairs, taking long strides or standing on one leg.
Discomfort when turning in bed, getting out of a car or rising from a chair.
Pain after prolonged standing or sitting.
Some people can point to a very specific painful area near the back of the pelvis. Others experience a more diffuse ache.
A useful clue: SI joint pain often lies below the level of the fifth lumbar vertebra (L5). However, the location and character of pain alone cannot confirm the diagnosis.
SI joint pain or slipped disc? How can you tell?
This is one of the most important questions in clinical practice.
| Feature | SI joint pain may present with | Lumbar disc or nerve-root pain may present with |
|---|---|---|
| Main location | Lower back near the buttock | Lower back, sometimes extending down the leg |
| Pain triggers | Stairs, single-leg loading, turning in bed | Bending, coughing or straining may aggravate symptoms |
| Leg symptoms | Usually buttock or thigh pain | May extend below the knee in nerve-root pain |
| Neurological symptoms | Not typical of isolated SI joint pain | Tingling, numbness or weakness may occur |
These are tendencies, not diagnostic rules. The conditions can coexist, and hip disorders, facet joint pain and other causes may produce similar symptoms.
The goal is not to guess which structure hurts, but to perform a systematic assessment.
How is SI joint pain diagnosed?
1. A detailed history
A clinician will ask about the location of pain, onset, injuries, pregnancy, previous spine surgery, inflammatory symptoms, aggravating activities and neurological complaints.
2. A focused physical examination
Several clinical tests attempt to reproduce the patient's familiar pain by stressing the SI joint region.
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FABER (Patrick's test)
The hip is placed in flexion, abduction and external rotation to assess pain arising from the hip or nearby structures.
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Thigh thrust test
A controlled force is applied through the femur to stress the SI joint region.
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Gaenslen's test
The pelvis is stressed using a combination of hip flexion and extension.
Other tests include SI joint distraction, compression and sacral thrust.
Clinicians commonly use a cluster of provocation tests, rather than relying on one positive test. Three or more positive tests may increase suspicion, but a positive cluster does not prove that the SI joint is the source of pain. Recent evidence suggests these tests are more useful for reducing suspicion when negative than for definitively confirming the diagnosis when positive.
3. Are X-rays or MRI necessary?
Not in every patient.
Imaging may be useful when the clinician suspects inflammatory sacroiliitis, fracture, infection, tumour or another condition that requires investigation. MRI can be particularly useful when inflammatory disease is suspected.
However, routine X-rays, CT scans or MRI cannot reliably establish that ordinary mechanical SI joint pain is the cause of symptoms. Imaging findings must be interpreted alongside the clinical picture.
4. When is a diagnostic injection considered?
If the diagnosis remains uncertain and the result would change treatment, a specialist may consider an image-guided injection of local anaesthetic into the joint.
Temporary pain relief after the injection can support the diagnosis of pain arising from inside the joint. Different pain generators, including the surrounding ligaments, may require a different assessment.
Treatment: Does SI joint pain always need an injection?
No. Most treatment plans should begin with an appropriate conservative approach, unless a specific underlying condition requires different management.
The right treatment depends on the cause, symptom severity, duration and effect on daily activities.
1. Physiotherapy and exercise
Rehabilitation should be individualised rather than based on a generic list of exercises.
A programme may include:
Gradual strengthening of the hip and trunk muscles.
Pelvic and trunk control exercises.
Graded walking and functional activity.
Movement strategies for stairs, transfers and prolonged standing.
Flexibility work where clinically appropriate.
Progressive return to work, sport or household activities.
The objective is to improve strength, load tolerance and confidence—not to force the pelvis into a supposedly perfect position. Evidence specifically for SI joint pain remains limited, but structured rehabilitation may provide benefit.
2. Activity modification
During a painful flare, temporarily reduce activities that clearly aggravate symptoms. This may mean shortening long walks, avoiding repeated heavy lifting or changing how you get in and out of a car.
Complete bed rest is generally not the answer. Gradual return to tolerable activity helps avoid unnecessary deconditioning.
3. Medication
Depending on the individual's medical history, a clinician may recommend a short course of an anti-inflammatory medicine or another suitable pain-relief option.
Medication choice should account for kidney disease, stomach ulcers, cardiovascular risk, pregnancy, other medicines and individual contraindications.
There is no single medicine that corrects every cause of SI joint pain.
4. SI joint belt
A pelvic belt may help some people, particularly selected patients with pregnancy-related pelvic girdle pain or symptoms associated with pelvic loading.
It should be considered a trial of symptom support—not a universal treatment or a substitute for assessment and rehabilitation.
5. Image-guided injections
For persistent, well-assessed SI joint pain that has not responded adequately to conservative care, a specialist may consider an image-guided corticosteroid injection.
Such injections can provide short-term relief in selected patients, but the response varies and relief may not be permanent. Fluoroscopy or CT guidance is generally preferred for accurate intra-articular injection.
Other procedures, including radiofrequency treatment of selected nerves supplying the posterior SI joint complex, may be considered in carefully selected patients after appropriate diagnostic assessment. Surgery is reserved for a small subset of patients with persistent, well-established SI joint pathology after other options have been considered.
When is SI joint pain a warning sign?
Do not assume every episode of buttock or lower back pain is mechanical SI joint pain.
Seek urgent medical assessment for:
New difficulty passing urine, loss of bladder or bowel control, or numbness around the groin or saddle region.
New or progressive leg weakness.
Fever or feeling severely unwell with back or pelvic pain.
Significant trauma or suspected fracture.
Severe, persistent or rapidly worsening pain, particularly with a history of cancer, immune suppression or recent serious infection.
These symptoms may indicate conditions that require urgent investigation rather than routine rehabilitation.
The rehabilitation physician's perspective
SI joint pain is a good example of why pain location alone is not a diagnosis.
Two patients may point to exactly the same area but need entirely different treatment. One may have mechanical pelvic girdle pain, another lumbar nerve-root irritation, and a third inflammatory sacroiliitis.
A rehabilitation-focused assessment considers more than the joint. It evaluates the spine, hips, neurological function, strength, balance, walking pattern, activity limitations and the patient's goals.
The treatment target is not merely to reduce pain on the examination table. It is to help the person walk, work, sleep, exercise and participate in everyday life with greater confidence.
Frequently asked questions about sacroiliac joint pain
Can SI joint pain heal on its own?
Some episodes improve with time, appropriate activity modification and gradual rehabilitation. Persistent or recurrent pain deserves assessment to confirm the likely cause.
Can SI joint pain cause sciatica?
It can cause pain that spreads into the buttock or thigh and may mimic sciatica. True nerve-root irritation should be considered when symptoms extend down the leg with neurological features.
Is walking good for SI joint pain?
Walking may help when tolerated. Begin with a comfortable duration and increase gradually; reduce the dose if it causes a substantial or lasting flare.
Can SI joint pain become chronic?
Yes. Persistent pain may be influenced by ongoing mechanical loading, associated conditions, deconditioning, sleep disruption and other individual factors. A tailored treatment plan can address these contributors.
Does SI joint pain always require an MRI or injection?
No. Neither is required in every case. Imaging is selected when it may identify an underlying condition, while diagnostic or therapeutic injections are reserved for appropriate clinical situations.
Final message: Find the cause before treating the pain
Pain near the back of the pelvis may originate from the sacroiliac joint—but it may also come from the spine, hip or surrounding tissues.
The best treatment begins with the right diagnosis, followed by a plan that restores movement and function.
If lower back or buttock pain is interfering with your walking, sleep or daily activities, seek a clinical assessment rather than relying on self-diagnosis.
Live • Heal • Move Forward
Dr. Abhinav Singh, MBBS,MD (PMR), FIPM
Pain & Rehabilitation Physician
Jeejeevisha Pain Clinic (JPC),
Contact: 9003843916
References for further reading
Multispecialty international consensus guidelines on SI joint complex pain, Pain Medicine, 2025.
Oxford Academic
+1
American Society of Pain and Neuroscience best-practice guideline for sacroiliac disorders.
PMC
Systematic review and meta-analysis of SI joint provocation test clusters, Journal of Orthopaedic & Sports Physical Therapy.
DOI
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