Infection Can Lead to Finger Amputation if Not Treated Quickly
Traumatic puncture wounds can lead to infection affecting the flexor tendon sheath (lining) of the fingers. It may seem like a small problem but it can lead to permanent stiffness of the affected finger(s) and palm. In worse case scenarios, amputation is even a possibility.

Quick and accurate diagnosis is needed to avoid such devastating consequences of this problem. In this article, hand surgeons from the University of North Carolina in Chapel Hill provide a detailed review of flexor tendon sheath infections of the hand. The intent is to help physicians respond appropriately to this injury.

Several pieces of information are crucial when examining a swollen, painful and tender, hot, and red finger. The first is a good knowledge of finger anatomy, especially of the flexor sheath system of the hand. Studies show there can be quite a bit of variation in the location and configuration of this area from one person to another. There are layers of connective tissue, a pulley system to bend the fingers, the blood vessels, and synovial fluid and the space for synovial fluid. The synovial system is key to providing smooth movement.

Second, the physician must be familiar with all possible causes of these same symptoms. Treatment and the speed at which surgery is considered depends on recognizing a true tendon sheath infection from other diagnoses. The differential diagnosis includes septic arthritis, tenosynovitis, herpetic whitlow, cellulitis, gout, pseudogout, and other hand infections.

Third, knowledge of the four Kanavel signs (named after Dr. Kanavel in 1933 that point to a flexor sheath infection is essential. These include: 1) symmetric (even) swelling of the entire finger, 2) extreme tenderness along the length of the tendon sheath, 3) finger in a slightly bent position, and 4) pain with any attempt by the physician to straighten the finger (passive extension).

Not all four signs have to be present to point to a flexor sheath infection. The two most common findings are tenderness along the sheath and pain with passive extension. Patients with other causes of similar symptoms do not have the Kanavel signs associated with flexor tendon infections.

The fourth important item for surgeons to understand when dealing with a potential flexor tendon sheath infection is the nature of bacteria, infection, and matching the most appropriate antibiotic with the bacteria present. Antibiotics are necessary and patients are put on a broad-spectrum antibiotic (one that will kill many different "bugs") until special tests called cultures are done to identify the specific bacteria present. Then the patient can be switched to a more specific antibiotic.

And finally, the physician must know what are the treatment options. Conservative (nonoperative) care with intravenous antibiotics, splinting, and elevation must show significant improvement within 48 hours. If there's been no improvement or the patient gets worse, then surgery to irrigate (clean out) and decompress (take pressure off) the tissue may be necessary.

The authors describe their own and others' surgical techniques including open and closed tendon sheath irrigation and continuous closed irrigation. Pros and cons of each from patient and surgeon point-of-view are offered. For example, closed technique is less painful and makes it possible for the patient to begin the necessary hand therapy sooner.

Complications are always a possibility after any traumatic injury but especially after one that leads to a flexor tendon sheath infection. Adhesions, joint capsular thickening, and destruction of the tendon pulley system by the infection can leave the patient with a permanently stiff finger. Skin infection can destroy enough skin that a skin graft is needed. Deep infection or infection that spreads can cause loss of tissue requiring amputation of the finger.

The potential for loss of a finger is why early and quick diagnosis and treatment are required. Even without the more serious complications, up to one-fourth of all patients with flexor tendon sheath infections lose their ability to straighten the affected finger. Anyone with diabetes is at increased risk for this type of infection. Other risk factors include age over 43, kidney or peripheral vascular disease, loss of blood supply to the area, and multiple bacteria present at the same time.

In summary, despite the small size of a finger infection, the medical consequences can be extreme. Anyone presenting with a red, tender or painful, swollen finger following trauma should be evaluated carefully. The four cardinal signs of Kanavel must be tested to rule out other potential causes. Treatment may begin with nonoperative care but must be quickly replaced with surgery if results are not seen within the first 24 to 48 hours. Physicians can find specifics of evaluation, treatment, surgical techniques, and complications for the problem of finger flexor infections in this detailed and comprehensive article.
Reid W. Draeger, MD, and Donald K. Bynum, Jr, MD. Flexor Tendon Sheath Infections of the Hand. In Journal of the American Academy of Orthopaedic Surgeons. June 2012. Vol. 20. No. 6. Pp. 373-382.