Introduction
Muscles are connected to the bones with the help of a fibrous tissue called a tendon. A protective sheath called a synovial membrane covers the tendons. It is also called a tendon sheath. It is the sheath that helps the tendons to move smoothly. Finger tendon sheath infections are approximately two to three percent of hand infections.
What Is Finger Tendon Sheath Infection?
Hand infections are common and can even cause death if left untreated. A bacterial infection can start in the tendon sheath in the hand's tendons. A fibrous tissue, a tendon, connects the muscles to the bones, which is covered by a protective sheath called a synovial membrane or tendon sheath. This sheath provides smooth movement of muscles. Finger tendon sheath infections are not so common.
An injury to the tendon can cause malfunctioning of the sheath covering it. As a result, the sheath may not be able to produce synovial fluid at all or in sufficient amounts. Synovial fluid is a fluid found in between the joints. This can cause inflammation of the sheath or swelling of the sheath. This condition is called tendon sheath inflammation. When an infection occurs in the finger, the condition is called a ‘finger tendon sheath infection.’
What Are the Synonyms of Finger Tendon Sheath Infection?
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Pyogenic flexor tenosynovitis.
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Flexor tendon sheath infection.
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Flexor tenosynovitis.
What Are the Causes of Finger Tendon Sheath Infection?
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A penetrating injury to the hand.
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A small hand injury in an immunocompromised person.
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A small bruise (like a rose thorn prick or a cat’s scratch) that was left unnoticed.
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Infections caused by staphylococcus aureus, pseudomonas aeruginosa, streptococcus species, etc. However, rare organisms like Pasteurella, Listeria, Neisseria gonorrhea, and Clostridium can cause the condition.
What Are the Signs and Symptoms of Finger Tendon Sheath Infection?
The common signs and symptoms of a finger tendon sheath infection are:
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Pain increases in intensity, usually in a single affected finger.
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Swelling of the finger with pain.
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Increased warmth and redness of the finger.
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Difficulty in bending the finger. The finger is usually held in a flexed or relaxed state.
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Inability to straighten the finger completely.
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Painful on pressing the affected finger in the front or the palmer area.
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The patient might not have any systemic changes; fever and myalgia (muscle and body pain) might be noticed as the condition progresses.
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A feeling of general illness as the condition advances.
How Is Finger Tendon Sheath Infection Diagnosed?
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The physical examination can include checking the hand for finger swelling, flexed posture, tenderness on palpation over the tendon sheath, redness, and other signs of inflammation. Signs of inflammation include rubor (redness of the skin), tumor (swelling), calor (the warmth of the area), and dolor (pain).
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Ultrasound findings supportive of the diagnosis include a collection of fluid within the synovial sheath, an increase in the diameter of the tendon, and disruption of the fibrillar organization.
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X-rays and other imaging modalities may not help diagnose the condition.
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A culture test can diagnose the type of infection or the organism causing the condition.
What Is the Kanavel’s Sign?
Kanavel’s sign is a clinical sign that has four parts. It helps in the diagnosis of a finger tendon sheath infection. However, it s not a validated method. The absence of one or more parts of the manifestation does not exclude the condition. A recent study shows the presence of all four signs only in about fifty percent of the cases. The four parts of the sign include the following:
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The flexed posture of the finger (the finger is held slightly in a bent position to relieve the pain).
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Swelling around the finger.
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Tenderness on percussion along the flexor tendon.
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Severe pain when the patient tries to extend (straighten) the finger.
Tenderness along the flexor sheath can be a late sign. But it is an important one in the diagnosis of the condition. The most commonly observed sign will be the swelling of the finger. The pain of the affected finger can also be frequent. These signs will be less prominent in the thumb and the little finger.
How Is Finger Tendon Sheath Infection Treated?
Early diagnosis and management of the condition can prevent surgical approaches or repeated surgeries. In the early stages, a finger tendon sheath infection can be managed by hospital admission, intravenous antibiotics, strict evaluation of the condition, and immobilization of the finger.
If a wound is found in the finger, washing of the wound will be required. Surgery might be required to wash out the infection if the early stage has passed while the wound is found. Incisions might be given on the finger to provide access to wash out the infection from the tendon sheath. Moderate to severe cases might require more than one surgery. The patient will be on intravenous antibiotics with an immobilized hand during this time. The surgeries are continued every twenty-four to forty-eight hours until the infection is resolved.
Very severe infections are common in aged patients, diabetic people, immunocompromised people, renal failure patients, lack of proper blood supply to the finger due to other factors, etc. Smoking reduces the blood flow to the fingers and delays healing. In extremely severe cases, the hand might become stiff or even dead, requiring an amputation (finger removal or elimination from the body).
After the infection has reduced to a point where intravenous antibiotics are no longer required, the patient can be sent home. Oral antibiotics will be given to resolve the infection completely. There will be incisions to drain the pus and a stent to immobilize the hand.
What Are the Differential Diagnoses of Finger Tendon Sheath Infection?
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Felon (a closed compartment infection in the fingertip).
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Deep space infections.
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Collar button infection (a deep space infection of the hand).
Conclusion
After the finger tendon sheath infection has been resolved completely, the patient will be advised to do exercises to improve the range of movement. Regaining the proper functioning of the hand might take some time.
