What is Enthesopathy?
Enthesopathy is a disease process occurring at the enthesis—the anatomical site where tendons, ligaments, joint capsules, or fascia insert into bone—and is characterized by pain, tenderness, and/or swelling at these insertion sites. 1, 2
Anatomical Definition
- The enthesis represents the specific anatomical location where tendon, ligament, or joint capsule fibers insert into bone 1
- These sites are areas of stress concentration and are commonly subject to pathological changes 3
- Entheses are enriched with free nerve endings, making them potential sources of chronic musculoskeletal pain (enthesalgia) 4
Clinical Presentation
Common anatomical sites of involvement include: 1, 2
- Plantar fascia insertion (heel)
- Achilles tendon insertion
- Ligamentous attachments to ribs, spine, and pelvis
- Femoral trochanter
- Humeral tuberosity
- Patella and olecranon
- Calcaneus
Clinical features include: 1, 5
- Stiffness, pain, swelling, and tenderness at insertion sites
- Symptoms may be accompanied by early morning stiffness lasting longer than 30 minutes (when inflammatory) 1
- Can occur at any enthesis site throughout the body
Pathophysiologic Categories
Enthesopathy can be classified by etiology: 2, 5, 4
- Inflammatory: Most notably in seronegative spondyloarthropathies (including psoriatic arthritis, ankylosing spondylitis, reactive arthritis) where it is a sine qua non feature 5
- Degenerative: Most sports-related enthesopathies are degenerative rather than inflammatory in nature 3
- Metabolic/Endocrine: Various metabolic and endocrine conditions may manifest with enthesopathy 4
- Traumatic/Occupational: Related to overuse injuries and mechanical stress 5, 3
- Drug-induced: Including retinoid-associated enthesopathy 6
- Calcium deposition diseases: May constitute the most significant articular cause of enthesopathies in the general population 4
Relationship to Specific Conditions
In psoriatic arthritis: 1
- Enthesitis is a characteristic feature alongside synovitis
- Dactylitis ("sausage digit") represents a combination of enthesitis of tendons/ligaments plus synovitis involving an entire digit
- Common in patients with nail disease and distal interphalangeal joint involvement
In inflammatory bowel disease: 1
- Peripheral arthropathy and/or enthesitis can occur as extra-intestinal manifestations
- Diagnosis is based on signs of inflammation and exclusion of other specific forms of arthritis
In juvenile idiopathic arthritis: 1
- Active enthesitis is defined as tenderness and/or swelling of the entheses requiring medical treatment
- Most commonly occurs in enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis categories
Radiographic Features
Specific radiographic findings include: 2
- Bone erosion at insertion sites
- Hyperostosis (new bone formation)
- Fragmentation
- Crystal deposition
- Periostitis 7
Advanced imaging considerations: 1
- Ultrasound with high-frequency transducers can detect enthesopathy and is cost-effective 5
- MRI is more sensitive for early inflammatory changes including bone marrow edema 1
- Both modalities outperform clinical examination for detecting enthesitis 1
Clinical Significance and Management
Key clinical pitfalls: 5
- Bursitis closely mimics enthesitis and must be differentiated
- Unrecognized and untreated enthesopathy can lead to considerable morbidity
- The muscle-tendon-bone unit should be considered as a whole when evaluating enthesopathies 3
Treatment approaches include: 5
- Local corticosteroid injections
- Physical therapy
- Non-steroidal anti-inflammatory drugs
- Treatment of the underlying primary disease process
In X-linked hypophosphataemia: 1
- Enthesopathies are prevalent in adults and usually detectable by the third decade of life
- Conventional therapy does not appear to prevent or treat these complications
- Physical therapy goals include pain relief, improved physical function, and reduced disability