Could Your Symptoms Be Spine Arthritis?
Your symptoms could indeed be spine arthritis, specifically axial spondyloarthritis (axSpA), which commonly affects the spine and sacroiliac joints, or rheumatoid arthritis if cervical spine involvement is present. The key is determining which type through systematic clinical evaluation and appropriate imaging.
Understanding Spine Arthritis Types
Two main inflammatory arthritides affect the spine:
- Axial Spondyloarthritis (axSpA): Primarily affects the sacroiliac joints and spine, typically presenting with inflammatory back pain in younger adults 1
- Rheumatoid Arthritis (RA): Selectively affects the cervical spine, causing atlantoaxial instability and potentially serious neurological complications 2, 3
Diagnostic Approach for Suspected Spine Arthritis
Initial Imaging Strategy
Start with conventional radiography of the sacroiliac joints and symptomatic spine areas as the first-line imaging method 1. This remains the recommended initial approach despite its limitations in early disease detection.
When Radiographs Are Negative or Inconclusive
If clinical suspicion for axSpA persists despite negative radiographs, MRI of the sacroiliac joints is the next essential step 1. MRI is the technique of choice for diagnosing axSpA because it detects both:
- Active inflammatory lesions: Primarily bone marrow edema, spondylitis, and spondylodiscitis 1
- Structural lesions: Bone erosions, new bone formation, sclerosis, and fat infiltration 1
The Role of Spine MRI
Spine MRI should be obtained when sacroiliac joint imaging is negative but clinical suspicion remains high 1. This is critical because:
- 5% of axSpA patients have inflammatory changes isolated to the spine only 1
- 1-49% of patients show isolated spinal involvement on MRI 1
- In early axSpA, 28.3% have inflammation involving both sacroiliac joints and spine 1
The ASAS (Assessment of SpondyloArthritis international Society) considers spine MRI positive for axSpA if there are three or more sites of inflammatory spondylitis 1. Multiple fatty corner lesions at several sites are also suggestive, especially in younger adults, with a specificity of 98% 1.
Key Imaging Findings to Look For
In Axial Spondyloarthritis:
Active inflammatory changes 1:
- Corner inflammatory lesions (≥2 lesions: 69% sensitivity, 94% specificity for AS) 1
- Lateral vertebral inflammatory lesions (97% specificity) 1
- Spondylitis and spondylodiscitis 1
- Costovertebral, costotransverse, and facet joint inflammation 1
Chronic structural changes 1:
- Syndesmophytes (slim ossifications between vertebral bodies) 1, 4
- Fatty deposition at vertebral corners 1
- Erosions and vertebral body squaring 1, 4
- Ankylosis and ligamentous ossification 1, 4
In Rheumatoid Arthritis:
Cervical spine involvement occurs in 9-88% of RA patients 3, typically after 10 years of disease but can occur as early as 3 months 3. Look for:
- Atlantoaxial subluxation and instability 2, 5
- Retroodontoid pannus formation 3, 5
- Cranial settling 5
- Subaxial subluxation 5
Critical Pitfalls to Avoid
Do not confuse inflammatory lesions with degenerative changes 1. MRI findings must be interpreted with attention to:
- Disc degeneration
- Osteophytes
- These favor degenerative disease rather than axSpA, though both inflammatory and fatty lesions can occur in degenerative changes 1
Always interpret spine MRI findings alongside sacroiliac joint MRI to ensure highest diagnostic utility 1.
Imaging Protocol Recommendations
For suspected axSpA, noncontrast MRI with STIR or T2-weighted fat-saturated sequences is generally sufficient 1. Contrast-enhanced MRI may increase diagnostic confidence and interpretation reliability but shows overall similar diagnostic utility to noncontrast imaging 1.
Consider whole-spine or whole-body MRI rather than selecting specific segments, as findings may be isolated to any portion of the spine 1.
When to Suspect Each Type
Suspect axSpA if:
- Younger adult (typically <45 years at onset)
- Inflammatory back pain pattern
- Symptoms improve with exercise, worsen with rest
- Involvement of sacroiliac joints and/or spine 1
Suspect RA cervical spine involvement if:
- Established RA diagnosis with cervical symptoms
- Neck pain with or without myelopathy
- Neurological symptoms suggesting cord compression 3, 5
Modalities NOT Recommended
Ultrasound is not beneficial for diagnosing spine arthritis due to limited evaluation of superficial posterior margins only 1. Bone scintigraphy and PET/CT lack established diagnostic utility and are not routinely recommended 1.