Infectious Tenosynovitis

Infectious (septic) tenosynovitis is infection within the closed space of the tendon sheath. It is usually is the result of penetrating trauma (animal or human bites) or extension of infection from adjacent tissues, although disseminated infection may also occur with some organisms (e.g., N gonorrhoeae).

Infectious tenosynovitis most frequently occurs in the tendons and tendon sheaths of the flexor muscles of the digits of the hand. Because tendons in the hand are next to or communicate with structures such as bursae and potential spaces, the spread of infection is a possibility. As an example, consider the radial and ulnar bursae, which are intimately associated with the flexor tendons of the thumb and small finger, respectively, and can become infected when nearby flexor tendons are infected. Because up to 80% of individuals have an anatomic communication between these bursae, infection in one can spread through this bursal communication to the opposite side of the hand (horseshoe abscess).

Failure to promptly treat flexor tendon sheath infection may lead to tendon necrosis and proximal spread. Adhesions and scarring may also result, leading to loss of mobility and contractures.

MRI usually reveals T1-hypointense and T2-hyperintense fluid distending the tendon sheath; however, the signal characteristics of the fluid can vary depending on the presence of debris, gas, or blood. In addition, the tendons lose their normal low signal intensity and become thickened and indistinct; the synovial lining of the tendon sheath thickens and becomes indistinct; and there is surrounding edema. Synovial enhancement is usually intense.

Case courtesy of the New England Baptist Hospital.

References

• Small LN, Ross JJ. Suppurative tenosynovitis and septic bursitis. Infect Dis Clin North Am. 2005 Dec;19(4):991-1005, xi.
• Turecki MB, Taljanovic MS, Stubbs AY, Graham AR, Holden DA, Hunter TB, Rogers LF. Imaging of musculoskeletal soft tissue infections. Skeletal Radiol. 2010 Oct;39(10):957-71.