What is enthesopathy?

Understanding Enthesopathy

Enthesopathy is a pathological condition affecting the entheses, which are the sites where tendons, ligaments, joint capsules or fascia attach to bone. 1

Definition and Anatomy

Entheses are crucial anatomical junctions where soft tissues connect to bone. These connection points serve as important stress concentration areas and are susceptible to various pathological processes. Enthesopathy encompasses any disease process occurring at these attachment sites and can be classified as:

• Inflammatory (enthesitis)
• Degenerative
• Metabolic
• Endocrine
• Traumatic 2, 3

Clinical Presentation

Patients with enthesopathy typically present with:

• Pain at attachment sites
• Tenderness on palpation
• Stiffness, particularly morning stiffness lasting more than 30 minutes (important diagnostic clue)
• Swelling around the affected area
• Limited range of motion
• Functional impairment 1, 3

Common Sites of Involvement

Enthesopathy can affect multiple sites throughout the body, with the most common locations being:

• Achilles tendon insertion
• Plantar fascia attachment to calcaneus
• Patellar tendon attachments
• Quadriceps tendon insertion
• Greater trochanter
• Humeral tuberosity
• Olecranon
• Pelvic attachments
• Vertebral column attachments 2, 4

Types and Causes

Inflammatory Enthesopathy (Enthesitis)

Inflammatory enthesopathy is a hallmark feature of seronegative spondyloarthropathies (SpA), including:

• Psoriatic arthritis - characterized by dactylitis ("sausage digit") and enthesitis 1, 5
• Ankylosing spondylitis
• Reactive arthritis
• Enteropathic arthritis associated with inflammatory bowel disease 1

Non-inflammatory Enthesopathy

• Mechanical/Overuse: Common in sports-related injuries (e.g., tennis elbow, golfer's elbow, jumper's knee, plantar fasciitis) 4
• Metabolic: Associated with crystal deposition diseases
• Endocrine: Seen in conditions like diabetes
• Degenerative: Age-related changes
• Drug-induced: Certain medications can cause enthesopathy 3

Diagnosis

Clinical Assessment

• Detailed history focusing on pain characteristics, morning stiffness, and associated conditions
• Physical examination to identify tenderness, swelling, and functional limitations
• Several validated physical examination measures exist for enthesitis assessment 5

Imaging

1. Ultrasound:

   • First-line imaging modality
   • 2.48-4.69 times better detection rate than clinical examination
   • Can identify synovial thickening, fluid in tendon sheath, and increased vascularity 6

2. MRI:

   • Superior for detecting early signs of enthesitis
   • Can evaluate both soft-tissue changes and intraosseous abnormalities
   • Particularly sensitive for detecting extracapsular inflammation 6, 7

3. Conventional Radiographs and CT:

   • Limited use in early disease
   • Helpful for detecting chronic changes like bone erosion, hyperostosis, fragmentation, and crystal deposition 2

Treatment Approaches

Non-pharmacological Management

• Relative rest and activity modification
• Splinting when appropriate
• Physical therapy with eccentric strengthening exercises
• Ergonomic education
• Cryotherapy (ice application) 6

Pharmacological Treatment

• NSAIDs: First-line for short-term pain relief (1-2 weeks)
• Corticosteroid injections: Effective for symptom relief, preferably with ultrasound guidance
• Disease-modifying antirheumatic drugs (DMARDs):
  • Conventional synthetic DMARDs (methotrexate preferred)
  • Biologic DMARDs for inadequate response to conventional therapy 6

Surgical Management

• Reserved for cases that fail conservative management
• May be considered after 4-6 months of unsuccessful conservative therapy 6

Clinical Significance and Prognosis

• Early detection and treatment are crucial to prevent long-term complications
• Untreated enthesopathy can lead to considerable morbidity
• Regular monitoring with ultrasound helps assess treatment response
• Enthesitis predicts erosive progression in inflammatory arthropathies 6, 3

Special Considerations

• Concomitant fibromyalgia in up to 20% of patients may complicate assessment and treatment
• Enthesopathy significantly impacts function and quality of life
• The concept of "enthesis organ" (collection of tissues adjacent to the enthesis that jointly dissipate stress) is important for understanding enthesopathies 4, 5

Early recognition and appropriate management of enthesopathy are essential to prevent disability and improve quality of life for affected individuals.