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Infectious Flexor Tenosynovitis

By David R. Steinberg, MD, Associate Professor, Department of Orthopaedic Surgery, and Director, Hand and Upper Extremity Fellowship, Perelman School of Medicine at the University of Pennsylvania

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Infectious flexor tenosynovitis is an acute infection within the flexor tendon sheath. Diagnosis is suggested by Kanavel signs and confirmed with x-rays. Treatment is surgical drainage and antibiotics.

The usual cause of infectious flexor tenosynovitis is a penetration and bacterial inoculation of the sheath.


  • Kanavel signs

  • X-rays

  • Culture of drainage or surgical sample

Infectious flexor tenosynovitis causes Kanavel signs:

  • Flexed resting position of the digit

  • Fusiform swelling

  • Tenderness along the flexor tendon sheath

  • Pain with passive extension of the digit

X-rays should be taken to detect occult foreign bodies. Acute calcific tendinitis and RA can restrict motion and cause pain in the tendon sheath but can usually be differentiated from infectious flexor tenosynovitis by a more gradual onset and the absence of some Kanavel signs. Disseminated gonococcal infection can cause tenosynovitis but often involves multiple joints (particularly those of the wrists, fingers, ankles, and toes), and patients often have recent fever, rash, polyarthralgias, and often risk factors for an STD. Infection of the tendon sheath may involve atypical mycobacteria, but these infections are usually indolent and chronic.


  • Surgical drainage and antibiotics

Treatment of infectious flexor tenosynovitis is surgical drainage (eg, irrigation of the tendon sheath by inserting a cannula into one end and allowing the irrigating fluid to pass along the tendon sheath to the other end). Antibiotic therapy (beginning empirically with a cephalosporin) and cultures are also required. In areas where methicillin-resistant Staphylococcus aureus (MRSA) is prevalent, trimethoprim/sulfamethoxazole, clindamycin, doxycycline, or linezolid should be used instead of a cephalosporin.