Imaging and intervention of sacroiliac joint Dr Ryan Lee Ka Lok Associate Consultant Prince of Wales Hospital
Introduction 15%-25% of low back pain is related to sacroiliac joint (SIJ) pain SIJ pain is usually under-diagnosed clinically
Anterior : Synovial joint Sacroiliac joint Posterior : ligamentous connection Sup Ant Post Inf
Sacroiliac joint
Iliac side Ant Post
Sacral side Ant Post
Imaging modalities XR USG CT NM Bone scan MRI
MRI Oblique axial Oblique coronal
Sagittal planning
Oblique axial True axial Oblique coronal True coronal
SIJ pathology 1. Inflammatory sacroiliitis 2. Infective sacroiliitis 3. Osteoarthrosis Rheumatic 4. Stress reaction/insufficiency fracture 5. Osteitis condensan ilii 6. Others : tumour Non-Rheumatic
1. Inflammatory sacroiliitis Sacroiliitis on imaging Plus >1 SpA feature or HLA-B27 plus >2 other SpA features Sacroiliitis on imaging: Active(acute) inflammation on MRI highly suggestive of sacroiliitis associated with SpA or Definite radiographic sacroiliitis according to modified New York criteria Assessment in SpondyloArthritis international society (ASAS) classification criteria for axial spondyloarthritis (SpA) 2009
A. Active (acute) sacroiliitis Bone marrow edema (BME)/osteitis Capsulitis Enthesitis Synovitis
Bone marrow edema / osteitis
Bone marrow edema / Osteitis T2W STIR Contrast T1W FS T2W STIR Contrast T1W FS
? Bone marrow edema / osteitis T2W STIR Contrast T1W FS
Bone marrow edema/osteitis At least one signal on consecutive slice
Bone marrow edema/osteitis Or more than one signal on single slice
Capsulitis Anterior capsulitis Posterior capsulitis
Enthesitis T2W STIR Contrast T1W FS
Enthesitis
Synovitis
B. Definite radiographic sacroiliitis According to modified New York Criteria Subchondral sclerosis Subchondral periarticular erosion Periarticular fat deposition Bony bridges / ankylosis
Grade Radiographic findings 0 Abnormalities are present 1 Suspicious areas are noted 2 Minor erosions 3 Unequivocal abnormalities in the joint 4 Severe change in the joint Modified New York criteria for the classification of ankylosing spondylitis Radiographic sacroiliitis + one clinical symptoms = AS Low back pain for at least 3 months improved by exercise and not relieved by rest Limitation of lumbar spine in sagittal and frontal planes Reduced chest expansion relative to normal values for age and sex Bilateral sacroiliitis grades 2-4 Unilateral sacroiliitis grades 3-4
Subchondral sclerosis T1W
Subchondral periarticular erosion Erosion Pseudo-widening
Peri-articular fatty infiltration T1W T1W T2W STIR
Bony bridges / Ankylosis
Radiograph Subchondral sclerosis and erosion Ankylosis
Radiographic involvement of sacroiliac joints in different conditions Bilateral, symmetric Ankylosing spondylitis Juvenile spondyloarthropathy (SpA) Osteitis condensus ilii Bilateral, asymmetric Psoriatic arthropathy IBD-associated SpA Reactive arthropathy Undifferentiated SpA Unilateral Infection (including TB) Malignancy
Joint fluid 2. Infective sacroiliitis Iliacus muscle involvement Gluteal muscle involvement
Infective sacroiliitis Iliacus and gluteal muscle involvement
Infective sacroiliitis Abscess T2W STIR Contrast T1W FS
TB sacroiliitis
Infective or inflammatory sacroiliitis?
3. Osteoarthritis
Osteoarthritis
4a. Stress reaction
4b. Stress fracture Honda sign
4c. Insufficiency fracture
4d. Stress related
5. Osteitis condensans ilii
Osteitis condensans ilii
Image guided intervention CT guided biopsy/aspiration CT guided injection USG guided injection Floroscopic guided injection
Joint fluid CT guided aspiration
Bone CT guided biopsy
CT guided pig tail insertion Needle Guidewire Dilator Pigtail
CT guided injection
CT guided injection
Ultrasound guided injection 2 nd sacral foramen
Floroscopic guided
Take Home Message MRI is imaging of choice to diagnosis different SIJ pathology CT is useful for SIJ related diagnostic and therapeutic intervention
End Thank You