Sacroiliac
Joint Dysfunction
Pain from the SI joint — where the spine meets the pelvis — that can closely mimic disc herniation or sciatica.
Sacroiliac Joint Dysfunction
Pain originating from the SI joint — the connection between the spine and pelvis — that can mimic spinal conditions.
SI joint dysfunction is frequently misdiagnosed as a lumbar spine problem. Getting the diagnosis right — including a diagnostic SNRB if needed — is essential before committing to any treatment.
Overview
The sacroiliac joint connects the sacrum — the triangular bone at the base of the spine — to the pelvis. Despite being a relatively small, low-motion joint, it is estimated to be the source of pain in 15–30% of patients presenting with low back pain. It is frequently overlooked in standard spine assessments and often misdiagnosed as lumbar disc disease.
What Causes It?
Pregnancy and childbirth are common triggers in women, due to ligamentous laxity and altered biomechanics. Leg length discrepancy, gait abnormalities, and prior lumbar fusion can also disrupt SI joint mechanics. Inflammatory conditions — ankylosing spondylitis, psoriatic arthritis — can affect the joint directly. In many cases, no specific cause is identified.
What Does It Feel Like?
One-sided lower back and buttock pain — typically with a point the patient can identify with one finger over the SI joint. Pain often worsens with transitioning from sitting to standing, prolonged standing, or climbing stairs. It may radiate into the groin or upper thigh but rarely below the knee — distinguishing it from true sciatica.
How Is It Diagnosed?
Clinical provocation tests — FABER, Gaenslen's, distraction and compression tests — help identify SI joint involvement. Definitive diagnosis requires a fluoroscopy-guided SI joint injection: if the pain is significantly reduced by anaesthetic injected into the joint, the diagnosis is confirmed. This is a diagnostic intervention, not just a treatment.
Non-Surgical Treatment
Physiotherapy targeting SI joint stabilisation — strengthening the gluteal, pelvic floor, and deep abdominal muscles — is the primary conservative approach. A sacroiliac belt can provide temporary relief by reducing joint movement. Corticosteroid injections into the joint under fluoroscopic guidance provide diagnostic confirmation and therapeutic relief simultaneously.
When Is Surgery Considered?
Surgery for SI joint dysfunction — SI joint fusion — is considered when conservative care including repeated injections has failed to provide adequate sustained relief, and when diagnostic injections have confirmed the joint as the pain source. It is a relatively uncommon procedure and requires careful patient selection.
The most important step with SI joint dysfunction is getting the diagnosis right. Treating it as a lumbar spine problem — when it isn't — will not help. The diagnostic injection is the key.
Recovery
Recovery following SI joint treatment depends on the approach. Conservative management with physiotherapy typically shows gradual improvement over 6–12 weeks. Following diagnostic and therapeutic injections, pain relief may be immediate and last weeks to months. After SI joint fusion, recovery is gradual — typically involving a period of protected weight-bearing followed by progressive physiotherapy over several months.
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A consultation will give you a clear diagnosis and a plan — conservative or surgical, whatever applies to your situation.