Sacroiliac Joint Pain

Pathophysiology

Source of primary low back pain &/or lower extremity pain in approximately 15-30% of patients with low back pain
Idiopathic
Extra-articular:
- Enthesis / ligamentous sprain
- Insufficiency fracture
- Fracture after major trauma
- Possible predisposition with ligamentous laxity conditions
Intra-articular:
- Osteoarthritis
- Infection
  - Usually haematogenous spread & unilateral
  - Occasionally iatrogenic, e.g post injection
  - Pseudomonas aeruginosa, Staphylococcus aureus, Cryptococcus, Mycobacterium tuberculosis
  - Predisposing factors include trauma, endocarditis, IVDU, & immunosuppression
- Inflammatory arthropathies
  - Ankylosing spondylitis
  - Reiter’s syndrome
  - Psoriatic arthropathy

Sacroiliac Joint Pain 1

- Metabolic processes
  - CPPD disease
  - Gout
  - Ochronosis
  - Hyperparathyroidism
  - Renal osteodystrophy
  - Acromegaly
- Tumours
  - GCT
  - Chondrosarcoma
  - Synovial villoadenoma
  - Metastases
- Instability
  - Iatrogenic (overzealous bone harvesting for grafts or from pelvic resection of tumours)
  - Pregnancy
    - Typically 3^rd trimester of pregnancy results in hypermobility of sacroiliac joint because of increased levels of estrogen & relaxin that cause soft tissues supporting joint to loosen – pain can develop earlier in some patients
    - This laxity may predispose sacroiliac joint ligaments to painful sprain
    - Mechanical trauma of childbirth also may cause joint pain
  - Lumbar spine fusion or hip arthrodesis may transfer additional forces to sacroiliac joint, creating cumulative stress and pain (43% of patients develop some level of sacroiliac degeneration within 5 years of lumbar fusion)

Differential Diagnosis

Intrinsic disk disease
Nerve root compression
Zygapophyseal joint pain
Primary or secondary myofascial syndromes
Non-spinal structures:
1. Gastrointestinal
2. Genitourinary
3. Gynecologic
4. Hip joint dysfunction

Diagnostic evaluation

Pain patterns:
- Referred pain to an area just inferior to ipsilateral PSIS
Physical examination:
- Used to exclude other diagnostic possibilities
- A false-positive straight leg raise test may occur when affected leg is elevated to approximately 60° because false dural tension symptoms are caused by sacroiliac joint motion at this degree of elevation
Imaging:
- Plain radiographs
  - AP pelvic & inlet & outlet views, and sacroiliac views +/- lateral sacrum
  - When instability suspected; single leg weight-bearing pelvic (flamingo) views
- CT, MRI, & bone scan may be done predominantly to exclude other causes of pain rather than to diagnose idiopathic sacroiliac joint pain

Diagnostic injections:
- Fluoroscopically or CT-guided, contrast-enhanced injections
- Maximum volume that should be injected into sacroiliac joint is 2.5 mL
- Excessive injectate can leak from anterior capsule onto regional neural structures & limit diagnostic specificity

Sacroiliac Joint Pain 2

Sacroiliac Joint Pain 3

Management

Medications:
- NSAIDs
- Non-opiate analgesics
- Opiates
- Anti-depressants
- Adjunctive medication including protease & TNF inhibitors
- Last 3 in liaison with rheumatologist & pain unit
Physical therapy:
- Education in & training of proper body mechanics & posture are essential, as is aerobic conditioning
- Flexibility & strength training (hamstrings, gluteus maximus & medius, piriformis, erector spinae, latissimus dorsi, & iliacus muscles)
- Avoid excessive hip external rotation and “clam” exercises
Braces (pelvic belt):
- May provide some pain relief &/or proprioceptive feedback
- Rapid weaning avoids psychological dependence & prevents decreased soft-tissue flexibility & potential muscular weakness
Injections (corticosteroid):
- Following minimum 4 weeks of appropriate, directed, noninvasive conservative care
- If pain substantially inhibits work or progress in physical &/or manual therapy, earlier use of an injection procedure may be diagnostic & may provide therapeutic benefit
Prolotherapy Injections:
- 3 separate image-guided intra-articular (+/- extra-articular) injections of 50% Dextrose, each injection given 3-4 weeks apart
- Reported to give benefit in 75-80% of patients
- Less successful if associated with ligamentous laxity syndrome
Radiofrequency neurotomy:
- Indicated after other, less invasive methods of care have been exhausted & diagnosis is proven for chronic joint pain
- L5 dorsal ramus, its branches to sacroiliac joint, & lateral branches of S1-S3 dorsal rami
- More effective for extra-articular than intra-articular joint pain
- 65% report >50% reduction of pain at 6-month follow-up
Arthrodesis:
- Considered only in patients with joint pain proven by controlled diagnostic anesthetic blocks & without any pain sources in lumbar spine
- It also should be reserved for those who continue to have disabling symptoms that have not responded to aggressive conservative care, i.e. failed non-operative programme
- Procedures
  - Anterior approach – Open ilioinguinal exposure with joint debridement, bone graft, and double-plate fixation – best for significant instability +/- ligamentous laxity patients
  - Posterior – Minimally invasive extra-articular approach using DIANA (Distraction Interference Arthrodesis with Neurovascular Anticipation) technique – Should not be used for ligamentous laxity patients
  - Direct Lateral/Transgluteal – Minimally invasive technique using iFuse 3D (better than original iFuse as allows extra bone graft) – Also quicker rehab protocol
  - Stabilisation with transiliosacral screws not recommended except in the acute trauma situation
- Post-operative care
  - PWB 3-12 weeks, depending on technique
  - Serial Xrays to confirm fixation and progressive union/fusion
  - CT to confirm consolidation in DIANA cases at 3 and 6 months