Spinal Arthritis Diagnostic Imaging Approach Part II

• Spinal Arthritis
• Ossification of Posterior Longitudinal Ligament (OPLL). Less frequent than DISH.
• Greater clinical importance d/t spinal canal stenosis and cervical myelopathy
• Asian patients are at higher risk
• Both OPLL & DISH may co-exist and increase the risk of Fx
• Imaging: x-rad: linear radioopacity consistent with OPLL
• Imaging modality of choice: CT scanning w/o contrast
• MRI may help  to evaluate myelopathy
• Care: surgical with laminoplasty (above right image) that has been pioneered and advanced in the Far East

M/C Inflammatory Arthritis In Spine

• Rheumatoid spondylitis (Rheumatoid arthritis) d/t inflammatory synovial proliferation pannus rich in lymphocytes, macrophages, and plasma cells
• C/S RA may affect 70-90% of patients
• Variable severity from mild to destructive disabling arthropathy
• RA IN C/S m/c affects C1-C2 due to an abundance of rich synovial tissue
• Typically infrequent in the thoracic/lumbar region
• Sub-axial C/spine may be affected later due to facets, erosions, ligament laxity and instability showing "Stepladder" appearance
• Clinically: HA, neck pain, myelopathy, etc. inc. Risk of Fx/subluxation. Any spinal manipulation HVLT ARE STRICTLY CONTRAINDICATED.
• Rx: DMARD, anti-TNF-alfa, operative for subluxations, etc.

Rheumatoid Spondylitis C1-C2. Perform X-radiography initially with flexed-extended views. Note Dens erosion, C1-2 subluxation (2.5 mm) that changes on mobility

• RA spondylitis: an erosion of the odontoid with the destruction of C1-C2 ligaments and instability
• Stepladder aka Step-step sub-axial deformity d/t facets erosions and ligamentous destruction/laxity
• MRI required to evaluate cord compression/myelopathy 

• Sagittal T2 WI MRI of pt with RA. Rheumatoid pannus formation is present at C1-2 (arrow) causing mild cord compression
• RA pannus may develop early before frank x-radiography changes noted
• Clinically: HA, neck pain, tingling in UE, positive Lhermitte phenomenon d/t cervical myelopathy

Operative Care of Rheumatoid Spondylitis and Its Complications

Seronegative Spondyloarthropathies

• Ankylosing Spondylitis (AS)
• Enteropathic Arthritis (EnA) (d/t IBD: Crohn's & UC) identical to AS on imaging
• Psoriatic Arthritis (PsA)
• Reactive Arthritis (ReA)
• All share the following features: m/c HLA-B27 marker, RF-, Sacroiliitis, Enthesitis, Ocular Involvement (i.e., conjunctivitis, uveitis, episcleritis, etc.)
• AS & EnA are radiographically virtually indistinguishable, but EnA typically presents with less severe spinal changes than AS
• Both PsA & ReA present with virtually identical spinal changes, but ReA typically affects the lower extremity compared to PsA affecting hands and feet

• AS: likely autoimmune systemic inflammatory disease that targets SIJ, spinal facet joints annuls of the disc, rib joints and all spinal ligaments.
• Key path feature: enthesitis.
• Extraspinal features: uveitis, aortitis, pulmonary fibrosis, amyloidosis, cardiovascular disease.
• M:F 4:1, age: 20-40 m/c. Clinic LBP/stiffness, reduced rib expansion <2 cm is > specific than HLA-B27, progressive kyphosis, risk of Fx's.
• Imaging steps: 1st step-x-rays to id. Sacroiliitis/spondylitis. MRI & CT may help if x-rays are unrewarding.
• Labs: HLA-B27, CRP/ESR, RF-
• Dx: clinical+labs+imaging.
• Rx: NSAID, DMARD, anti-TNF factor therapy
• Key Imaging Dx: always presents initially as b/l symmetrical sacroiliitis that will progress to complete ankylosis. Spondylitis presents with continuous ascending discovertebral osteitis (i.e., marginal syndesmophytes, Romanus lesion, Anderson lesion), facets and all spinal ligament inflammation and fusion with a late feature of "bamboo spine, trolley track, dagger sign," all indicating complete spinal ossification/fusion. Increasing risk of Fx's.

Key Dx of Sacroiliitis

• Blurring, cortical indistinctness/irregularity with adjacent reactive subchondral sclerosis initially identified primarily on the iliac side of  SIJs.
• Normal SIJ should maintain a well defined white cortical line. Dimension 2-4 mm. May look incongruous d/t 3D anatomy masked by 2D x-rays.

Key Imaging Dx In Spine

• Marginal syndesmophytes and inflammation at the annulus-disc (above arrows) at the earliest dx; by MRI as marrow signal changes on T1 and fluid sensitive imaging (above top images). 
• These represent enthesitis-inflammation that will ossify into bamboo spine.
• Lig ossification: trolley track/dagger sign

• AS in extraspinal joints: root joints, hips, and shoulders
• Symphysis pubis
• Less frequent in peripheral joints (hands/feet)
• All seronegatives may present with heel pain d/t enthesitis

• Complication: Above Carrot-stick/chaulk-stick Fx

• PsA & ReA (formerly Reiter's) present with b/l sacroiliitis that virtually identical to AS
• In the spine PsA & ReA DDx from AS by the formation of non-marginal syndesmophytes aka bulky paravertebral ossifications (indicate vertebral enthesitis)
• For a clinical discussion of Spondyloarthropathies refer to:
• https://www.aafp.org/afp/2004/0615/p2853.html

Spinal Arthritis