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What is Tenosynovitis and explain in detail?
Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical manifestations of noninfectious tenosynovitis include de Quervain tendinopathy and stenosing tenosynovitis (more commonly known as trigger finger)

Signs and symptoms
Infectious tenosynovitis occurs between 2.5% and 9.4% of all hand infections. Kanavels cardinal signs is used to diagnose infectious tenosynovitis. They are: tenderness to touch along the flexor aspect of the finger, fusiform enlargement of the affected finger, the finger being held in slight flexion at rest, and severe pain with passive extension. Fever may also be present but is uncommon.

Pathogenesis
Infectious tenosynovitis is the infection of closed synovial sheaths in the flexor tendons of the fingers. It is usually caused by trauma, but bacteria can spread from other sites of the body. Although tenosynovitis usually affects the flexor tendon of the fingers, the disease can also affect the extensor tendons occasionally. The clinical presentation is therefore as acute infection following trauma. The infection can be mono- or polymicrobial and can vary depending on the nature of the trauma. The most common pathogenic agent is Staphylococcus aureus introduced from the skin. Other bacteria linked to infectious tenosynovitis include Pasteurella multocida (associated with animal bites), Eikenella spp. (associated with IV drug use), and Mycobacterium marinum (associated with wounds exposed to fresh or salt water). Additionally, sexually active patients are at risk for hematogenous spread due to Neisseria gonorrhoeae (see infectious arthritis).
Common noninfectious tenosynovitis are: stenosing tenosynovitis, intersection syndrome, extensor pollicis longus (EPL) tenosynovitis, de Quervains and fourth compartment tenosynovitis.

Diagnosis
Diagnosis of tenosynovitis is typically made clinically after a thorough patient history and physical exam