Sacroiliac Joint Dysfunction

Pain arising from the sacroiliac joint or its supporting ligaments, due to abnormal movement (hypermobility or hypomobility), inflammation, degeneration or mechanical overload. It accounts for about 15 to 30% of axial low back pain in adults with persisting symptoms.

• Causes and associations:
  • Pregnancy and delivery (ligament laxity from relaxin and mechanical load), the commonest cause in women.
  • Trauma (fall onto the buttock, motor vehicle collision), repetitive asymmetric loading (running, golf, rowing), leg length discrepancy (above 1 cm).
  • Lumbar fusion (adjacent segment loading), scoliosis, and gait abnormality.
  • Degenerative osteoarthritis of the joint.
  • Inflammatory sacroiliitis in spondyloarthritis (ankylosing spondylitis, psoriatic arthritis, inflammatory bowel disease), and infection (septic sacroiliitis, tuberculosis, brucellosis).
  • Crystal arthropathy and metastasis (rare).
• The diagnosis is difficult, because no single examination or imaging finding is reliable, and it overlaps with facet, disc, hip and gluteal pain.
• Peak age is 20 to 50 years in mechanical disease. Inflammatory sacroiliitis starts before 45 years.

• Unilateral (sometimes bilateral) pain in the low back, centred near the posterior superior iliac spine, with referral to the buttock, posterior thigh, groin or, less often, below the knee. Patients point to the posterior superior iliac spine with one finger (Fortin finger sign), typically about 2 cm distal and medial to it.
• Pain is worse with prolonged sitting, standing, climbing stairs, rolling in bed, rising from sitting, and walking, and eased by changing position. Pain on weight bearing on the affected leg and putting on socks.
• Examination: tenderness over the sacral sulcus and the sacroiliac ligaments, and provocation tests. A cluster of at least 3 positive tests out of 5 (distraction, compression, thigh thrust, Gaenslen and sacral thrust) has useful diagnostic value:
  • Distraction (gapping) test: pressure on the anterior superior iliac spines with the patient supine.
  • Compression test: side lying pressure on the iliac crest.
  • Thigh thrust (posterior shear): axial load along the femur with the hip flexed 90 degrees.
  • Gaenslen test: hyperextension of one hip with the other flexed.
  • Sacral thrust: downward pressure on the sacrum with the patient prone.
• Straight leg raise is negative for root tension, and neurological examination is normal.
• Inflammatory features: onset below 40 years, insidious, morning stiffness above 30 minutes, improvement with exercise and not rest, alternating buttock pain, night pain in the second half, uveitis, psoriasis, bowel disease and family history.
• Differential diagnosis: lumbar facet syndrome, lumbar disc herniation or radiculopathy, hip osteoarthritis and femoroacetabular impingement, piriformis syndrome, gluteal tendinopathy, spinal stenosis, coccydynia, stress fracture of the sacrum (osteoporosis, athletes), spondyloarthritis, infection, tumour, endometriosis, and pelvic girdle pain.
• Red flags: fever (septic sacroiliitis), severe unilateral buttock pain with inability to bear weight, weight loss, history of cancer, and cauda equina features.
• Complications: chronic pain and disability, gait alteration, sleep disturbance, and in inflammatory disease, structural damage and ankylosis.

• Clinical, using the provocation test cluster, the Fortin sign and exclusion of lumbar and hip causes.
• X-ray of the pelvis (anteroposterior) shows degenerative change, sclerosis, erosions or fusion. It is insensitive in early disease.
• MRI of the sacroiliac joints (short tau inversion recovery and T1 sequences) is the best test for active inflammation (bone marrow oedema), erosions, fat metaplasia, infection and stress fracture. Computed tomography shows structural change in detail.
• Diagnostic intra articular injection (fluoroscopy, CT or ultrasound guided) of local anaesthetic (lidocaine 1% 1 to 2 mL, or bupivacaine 0.5% 1 to 2 mL) with at least 75% relief of pain (and ideally 80% with a dual block) confirms a sacroiliac source.
• Blood tests when inflammatory or infectious disease is possible: CRP, ESR, HLA-B27, full blood count, and cultures. Tests for tuberculosis and brucellosis in endemic areas.
• Check bone density and vitamin D when stress fracture is possible.

• Education and activity modification: avoid prolonged asymmetric loading (standing on one leg, sitting cross legged, carrying loads on one side), use a firm chair, sleep with a pillow between the knees, and correct leg length discrepancy with a heel lift when above 1 cm.
• Analgesia: paracetamol 1 g orally 6 hourly. NSAIDs for 1 to 2 weeks (ibuprofen 400 mg 8 hourly with food, naproxen 500 mg 12 hourly, or diclofenac 50 mg 8 hourly, with gastroprotection if at risk). Topical diclofenac 1% gel 2 to 4 g 3 to 4 times daily. Heat before exercise, ice after activity.
• Pelvic belt: a trochanteric pelvic support belt, positioned at the level of the greater trochanters, reduces pain in many patients (especially in pregnancy and hypermobility) during activity.
• Physiotherapy (the mainstay), 6 to 12 weeks:
  • Stabilisation exercises targeting the gluteus maximus, deep abdominal muscles (transversus abdominis), multifidus and pelvic floor, with progression to functional loading.
  • Manual therapy and mobilisation of the sacroiliac joint for hypomobility.
  • Stretching of the hip flexors, hamstrings, piriformis and adductors, and gait retraining.
• Corticosteroid injection for pain that persists after 6 to 8 weeks of rehabilitation: triamcinolone acetonide 40 mg (or methylprednisolone acetate 40 mg) with lidocaine 1% 1 to 2 mL (or bupivacaine 0.25%), into the joint (intra articular) under fluoroscopic, CT or ultrasound guidance, with additional periarticular injection of ligaments in some practices. Relief lasts weeks to months in about 50 to 70% of patients with confirmed sacroiliac pain. Limit to 3 to 4 injections per year. Warn of transient glucose rise in diabetes.
• Radiofrequency denervation of the lateral branches of the sacral dorsal rami (conventional, cooled or bipolar) for patients with 2 positive diagnostic blocks, giving relief of 3 to 12 months in about 50 to 60% of patients, and repeated if effective.
• Prolotherapy (dextrose 15 to 25% injected into the posterior ligaments) and platelet rich plasma have emerging, limited evidence.
• Surgical fusion of the joint (open or minimally invasive with implants) is reserved for carefully selected patients with disabling pain, positive blocks and failure of 6 or more months of conservative and interventional treatment, with a modest success of about 60 to 70%.
• Inflammatory sacroiliitis (spondyloarthritis): NSAIDs at the full dose (naproxen 500 mg 12 hourly, or celecoxib 200 to 400 mg daily, or etoricoxib 90 mg daily) for 2 to 4 weeks, with daily exercise. Refer to rheumatology for biologic therapy (TNF inhibitors such as adalimumab 40 mg every 2 weeks, or IL-17 inhibitors such as secukinumab 150 mg monthly after loading) if inadequate response after 2 NSAIDs over 4 weeks.
• Septic sacroiliitis: blood cultures, aspiration if possible, and prolonged IV antibiotics (flucloxacillin 2 g 6 hourly or vancomycin 15 to 20 mg/kg 8 to 12 hourly adjusted to levels, for 4 to 6 weeks), with surgical debridement when needed. Treat tuberculosis and brucellosis with the appropriate multidrug regimens.
• Special groups:
  • Pregnancy and postpartum: pelvic support belt, physiotherapy, positioning advice, and paracetamol. Avoid NSAIDs after 20 weeks. Symptoms usually settle within 3 to 6 months after delivery.
  • Athletes: correct technique and loading asymmetry, and core and gluteal strengthening.
  • Elderly: assess for sacral insufficiency fracture and osteoporosis.
  • Diabetes: monitor glucose after steroid injection.
  • Anticoagulation: plan injection with prescriber input.
• Follow up: review at 6 weeks. Refer to physiotherapy, pain medicine, rheumatology (for suspected inflammatory disease) or spinal surgery for persistent pain beyond 3 months, red flags, or need for interventions.