Tenosynovitis vs. Tendinitis: Understanding the Difference
No, tenosynovitis and tendinitis are not the same condition - tenosynovitis is inflammation of the synovial sheath surrounding a tendon, while tendinitis is inflammation of the tendon itself. 1
Anatomical Differences
Tenosynovitis
- Involves inflammation of the synovial sheath that surrounds certain tendons
- Affects tendons that run through synovial sheaths or tunnels
- Can present as exudative (with fluid accumulation) or stenosing (with narrowing of the tunnel) 2
- Often involves thickening of the retinaculum or pulley that constricts the osseofibrous tunnel 1
- Common locations include wrist tendons, finger flexor tendons, and ankle tendons
Tendinitis
- Involves inflammation of the tendon tissue itself
- Can occur in any tendon, including those without synovial sheaths
- Often occurs at tendon attachment sites (enthesitis)
- Note: Some researchers question whether true inflammatory tendinitis exists, as pathoanatomic studies have not clearly demonstrated inflammation within tendon tissue 3
Clinical Presentation
Tenosynovitis
- Presents with pain, swelling, and sometimes crepitus along the tendon sheath
- May cause triggering or catching in stenosing forms
- Often produces palpable thickening of the tendon sheath
- May restrict tendon movement through its sheath
- Can be detected on ultrasound as fluid within the tendon sheath or thickening of the sheath 4
Tendinitis
- Presents with localized pain and tenderness over the tendon
- Pain typically worsens with active movement or resistance against the affected tendon
- May show thickening of the tendon itself rather than the sheath
- Often lacks the crepitus characteristic of tenosynovitis
Diagnostic Differentiation
Ultrasound is particularly helpful in distinguishing between these conditions:
- In tenosynovitis: fluid within the tendon sheath, thickening of the synovial sheath, or narrowing of the osseofibrous tunnel can be visualized 4
- In tendinitis: changes in the tendon itself such as thickening, hypoechogenicity, or hypervascularity may be seen
MRI can also differentiate between:
- Tenosynovitis: showing increased fluid signal in the tendon sheath
- Tendinitis: showing signal changes within the tendon substance 4
Clinical Significance
The distinction is important because:
- Treatment approaches may differ
- Tenosynovitis may require different interventions, especially in stenosing forms
- Prognostic implications may vary
- Underlying causes may differ (mechanical, inflammatory, infectious) 2
Common Examples
Tenosynovitis:
- De Quervain's tenosynovitis (first dorsal compartment of wrist) 5
- Trigger finger (stenosing tenosynovitis of finger flexor tendons) 1
- Posterior tibial tendon tenosynovitis 6
Tendinitis:
- Achilles tendinitis
- Patellar tendinitis
- Lateral epicondylitis (tennis elbow)
Treatment Considerations
Both conditions may initially be treated with:
- Rest and activity modification
- NSAIDs for pain and inflammation
- Physical therapy
However, specific treatments differ:
- Tenosynovitis may benefit from corticosteroid injections into the tendon sheath 5, 7
- Stenosing tenosynovitis may require surgical release of the constricting pulley or retinaculum 5
- Tendinitis treatment focuses more on eccentric strengthening and addressing biomechanical factors
Conclusion
While both conditions involve tendon pathology and may coexist, they represent distinct entities affecting different anatomical structures. Proper differentiation is essential for appropriate management and treatment selection.