Infectious tenosynovitis

Last revised by Ali Alsmair on 16 Mar 2022

Infectious or septic tenosynovitis refers to an infection of the closed synovial tendon sheath 1-3.

The term ‘infectious or septic tenosynovitis’ applies for tendons with a tendon sheath, for tendons without a tendon sheath with a paratenon the term ‘infective paratenonitis’ can be used 1.

Risk factors of infectious tenosynovitis include 4,5:

Infectious tenosynovitis might be associated with the following conditions 1-5:

The diagnosis of infectious tenosynovitis can be made by a combination of typical clinical features of infection in the setting of characteristic imaging findings 1 and can be verified by the culture of the purulent synovial fluid.

A synovial biopsy can be obtained in the setting of suspected granulomatous infection.

Symptoms of infectious tenosynovitis include swelling, erythema, tenderness, warmth and painful range of motion of the respective tendon 2. Laboratory studies might show increased inflammatory markers such as leukocyte count or c-reactive protein (CRP).

Complications of a soft tissue abscess include the following 2,3:

The underlying pathologic correlate of infectious tenosynovitis is an infection and/or pus within the tendon sheath sometimes also leading to adhesions and septations 1,2.

Infectious tenosynovitis is usually a result of a contiguous spread from an underlying ulcer or septic arthritis or direct infection via skin breach 1,2. Less often it can happen due to hematogenous seeding 2.

Potential organisms of infectious tenosynovitis include pyogenic bacteriae, mycobacteria and fungi 2.

The hand and wrist are the most common location of infectious tenosynovitis, especially the flexor compartment in the setting of pyogenic flexor tenosynovitis 2-4. Tendon infections have been also described for other sites including the wrist extensor tendons the flexor and extensor tendons of the foot and ankle 5,6 and the long head biceps tendon 7.

On imaging tenosynovitis is characterized by fluid within the tendon sheath, that might show different to complex signal characteristics depending on whether pus, gas or blood products are present, which favor an infective cause over a pure inflammatory origin 1,2.

Plain x-rays are only of limited value in the diagnosis of infective tenosynovitis but can display soft tissue swelling and/or gas or foreign bodies as a potential cause 2,3.

Ultrasound might show synovial hyperemia and fluid distension of the tendon sheath 2,3.

CT might demonstrate fluid and/or gas within the tendon sheath, synovial thickening and enhancement 2,3.

MRI is considered the preferred modality for the assessment of tenosynovitis and might show the following 1-3:

  • a complex, inhomogeneous fluid signal within the tendon sheath
  • soft tissue-edema like signal around the tendon sheath
  • synovial thickening with contrast enhancement
  • synovial adhesions/septations
  • thickened tendons with variable signal alterations and/or enhancement

The radiological report should contain a description of the following 1-3:

  • presence of tenosynovitis
  • presence of adhesions, gas, blood products within the tendon sheath
  • associated findings
    • ulcer, skin breach
    • overlying cellulitis/soft tissue swelling
    • adjacent bone erosion
    • joint effusion/septic arthritis
    • bursitis
    • foreign body

The management of infectious tenosynovitis is surgical and considered an emergency 2,4. Additional measures include administration of antibiotics, splinting and limb elevation.

Conditions mimicking the radiological appearance of infectious tenosynovitis include 1,2:

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