Last revised by Karen Machang'a on 9 Oct 2023

Tenosynovitis is a term describing the inflammation of the synovial membrane surrounding a tendon. It may be seen with or without tendinosis/tendinitis. The synovial membrane is part of a fluid-filled sheath that surrounds a tendon.

  • joint swelling
  • pain in the affected area
  • pain/difficulty moving a joint
  • erythema along the length of the affected tendon

Tenosynovitis can be caused by a variety of disease processes, including, but not limited to:

Plain radiographs are non-diagnostic but may show calcification of one or several synovial membranes (suggestive of hydroxyapatite deposition/chondrocalcinosis) and a periosteal reaction in an adjacent bone.

The synovial membrane is not identified unless there is a pathological swelling. Tenosynovitis is characterized by increased fluid content within tendon sheath, thickening of the synovial sheath with or without increased vascularity which can extend into the tendon sheath, and peritendinous subcutaneous edema. Subcutaneous edema can result in a hypoechoic halo sign and peritendinous subcutaneous hyperemia on Doppler imaging.

Color Doppler ultrasound is an important part of the tendon sheath assessment; it can differentiate between synovial thickening which is more suggestive of chronic disease, and turbid tendon sheath fluid collection - more indicative of acute exudative tenosynovitis. In chronic inactive disease, however, there is synovial thickening with minimal vascularity. 

Increased fluid within tendon sheath:

  • T1: low or intermediate if debris within tendon sheath 
  • T2: high
  • T1 C+ (Gd): tendon sheath thickening and peritendinous subcutaneous contrast enhancement

Treatments may include activity modification, rest, non-steroidal anti-inflammatory drugs, bandage or splint, and/or cold therapy. Surgical procedures to release the tendon rarely have a role. If tenosynovitis persists after a period of rest and infection has been excluded, a steroid injection may provide symptomatic relief. If the tenosynovitis is infective, urgent surgical assessment is required. Physiotherapy is an option.

If the tendon communicates with a joint, such as the long head of biceps at the shoulder and flexor hallucis longus at the ankle, then no fluid should be present in the joint to make the call.

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Cases and figures

  • Case 1: ECU tendinosis and tenosynovitis
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  • Case 2: ECU tenosynovitis
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  • Case 3: 4th extensor compartment tenosynovitis
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  • Case 4: suppurative tenosynovitis of peronii tendons
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  • Case 5: tibialis anterior tenosynovitis - on ultrasound
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  • Case 6: flexor hallucis longus tenosynovitis
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  • Case 7: peroneal tendons (with PB split tear)
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  • Case 8: extensor digitorum longus tenosynovitis
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  • Case 9: fourth extensor compartment tenosynovitis
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