What is spinal enthesopathy?

Spinal Enthesopathy: Definition, Diagnosis, and Management

Spinal enthesopathy is an inflammatory or degenerative condition affecting the sites where tendons, ligaments, or joint capsules attach to the vertebral bones, characterized by pain, stiffness, and potential structural changes that can significantly impact mobility and quality of life.

Definition and Pathophysiology

Entheses are the attachment sites of tendons, ligaments, or joint capsules to bone 1. Spinal enthesopathy refers specifically to disease processes occurring at these attachment sites within the vertebral column. The condition can be:

• Inflammatory: Often associated with spondyloarthropathies
• Degenerative: Related to age-related changes or mechanical stress
• Traumatic: Following injury to attachment sites
• Metabolic/Endocrine: Related to systemic conditions

The "enthesis organ concept" explains why enthesopathy symptoms may be more diffuse than expected. This concept recognizes that stress at insertion sites affects not only the enthesis itself but also neighboring tissues including fibrocartilage, bursae, fat pads, adjacent trabecular bone, and sometimes deep fascia 2.

Clinical Presentation

Patients with spinal enthesopathy typically present with:

• Axial spine pain (neck, mid-back, or low back)
• Morning stiffness lasting >30 minutes
• Pain that improves with activity but worsens with rest
• Tenderness at specific attachment sites
• Limited spinal mobility
• Potential radiation of pain to buttocks or proximal limbs

Diagnostic Approach

Imaging Studies

1. Radiography: First-line imaging modality 3

   • May show erosions, sclerosis, hyperostosis, or fragmentation at entheseal sites
   • Limited sensitivity for early disease

2. MRI: Essential for identifying early inflammatory changes 3

   • Requires T1-weighted sequences and fat-suppressed fluid-sensitive sequences (T2-weighted fat-suppressed or STIR)
   • Can detect bone marrow edema, the hallmark of active inflammation
   • Particularly useful when radiographs are negative but clinical suspicion remains high

3. CT: Useful for evaluating structural changes 3

   • Better visualization of subtle erosions and soft-tissue ossification
   • Particularly valuable for thoracic spine and facet joints
   • Higher sensitivity than radiography for detecting early enthesopathy-related bone changes

Laboratory Tests

• HLA-B27: High sensitivity (90-95%) in inflammatory enthesopathy related to axial spondyloarthritis 4
• CRP and ESR: May be elevated in inflammatory enthesopathy, but normal values don't exclude the diagnosis 4

Differential Diagnosis

Spinal enthesopathy must be distinguished from:

1. Degenerative disc disease: Primarily affects the intervertebral discs rather than attachment sites
2. Facet joint arthropathy: Primarily affects the synovial joints of the spine
3. Spinal stenosis: Narrowing of the spinal canal causing neurological symptoms
4. Vertebral compression fractures: Acute onset, often related to trauma or osteoporosis
5. Inflammatory spondyloarthropathies: May coexist with enthesopathy but represent a broader systemic condition

Management Approaches

Non-inflammatory Enthesopathy

1. Conservative Management:

   • Physical therapy focusing on core strengthening
   • Activity modification
   • NSAIDs for pain control
   • Heat/cold therapy

2. Injection Therapy:

   • Local anesthetic injections provide short-term relief
   • Prolotherapy (phenol-glycerol proliferant) may provide longer-lasting relief than anesthetics alone 5
   • In one study, 80% of patients reported good to excellent relief after prolotherapy injections versus 47% with anesthetics alone 5

3. Surgical Intervention:

   • Reserved for cases with significant structural changes causing neurological compromise
   • May be considered when conservative measures fail

Inflammatory Enthesopathy (Associated with Spondyloarthropathies)

1. NSAIDs: First-line treatment 4

2. Biologic Therapies (if NSAIDs insufficient):

   • TNF inhibitors recommended as first-line biologics 4
   • IL-17 inhibitors (secukinumab, ixekizumab) recommended for those with primary non-response to TNF inhibitors 4

3. Regular Assessment:

   • Monitor disease activity using validated tools like ASDAS-CRP 4
   • Repeat imaging no more frequently than every 2 years 4

Prognosis and Complications

• Without appropriate treatment, spinal enthesopathy can lead to progressive structural changes
• In inflammatory cases associated with ankylosing spondylitis, spinal fusion may occur
• Patients with spinal ankylosis have increased risk of unstable fractures even with minor trauma 4
• Chronic pain can significantly impact quality of life and functional capacity

When to Refer

• Patients with suspected inflammatory enthesopathy should be referred to a rheumatologist 4
• Those with refractory pain or significant structural changes may benefit from orthopedic evaluation 4
• Pain management specialists may help with complex pain control strategies

Common Pitfalls in Diagnosis

• Over-reliance on radiographs (may miss early disease)
• Ignoring inflammatory back pain patterns
• Neglecting extra-articular manifestations
• Misinterpreting normal inflammatory markers as excluding the diagnosis

Spinal enthesopathy represents an important but often overlooked cause of axial pain that requires appropriate imaging and potentially specialized treatment approaches depending on the underlying etiology.