Tendon Sheath Infection

An infection within the synovial sheath of the flexor tendons is one of the most serious of all hand infections. Prompt surgical drainage is critical, for a long-standing infection almost always results in fibrosis within the tendon sheath and subsequent tethering of the tendon itself. Sheath infections are caused by spread from a pulp infection or by puncture wounds, particularly at the flexor creases.

The diagnosis is made clinically. The finger held in a flexed position is grossly swollen and tender. The slightest active or passive extension of the digit produces severe pain, which is the cardinal physical symptom on which the diagnosis is based.

These infections are not as common as they used to be as a result of earlier diagnosis and treatment of superficial finger infections. Nevertheless, they still occur and offer a true orthopedic emergency.

Position of the Patient

Place the patient supine on the operating table, with the arm extended on

an arm board. A tourniquet is essential, but the arm should not be exsanguinated as it is with general anesthesia or a proximal local block (either brachial or axillary). Good lighting and fine instruments minimize the risk of damaging the vital structures within the hand (see Fig. 5-15).

Landmarks and Incision

Landmarks

The distal palmar crease roughly marks the palmar site of the metacarpophalangeal joints and the proximal border of the fibrous flexor sheath of the flexor tendons.

The distal interphalangeal crease is the surface marking of the distal interphalangeal joint and lies just proximal to the distal end of the fibrous flexor sheath.

Incision

Make a small transverse incision just proximal to the distal palmar crease and over the infected flexor tendon. The incision should be 1.5 to 2.0 cm long (Fig. 5-78).

A second incision usually is necessary if there is turbid fluid within the sheath. Make a midlateral cut over the distal end of the middle phalanx in the line connecting the dorsal ends of the proximal and distal interphalangeal creases (see Fig. 5-78A).

Figure 5-78 Incision for infection of the flexor digital sheath. Make a small transverse incision just proximal to the distal palmar crease, over the infected flexor tendon. A: A second incision may be necessary, and this should be made over the distal end of the middle phalanx in the midlateral position. B: Separate the longitudinally running fibers of the palmar aponeurosis. C: Incise the A1 pulley to reveal the underlying synovial sheath, which then should be opened.

Internervous Plane

There is no internervous plane in this approach. The midlateral approach is roughly in the line of demarcation between skin that is supplied by the digital nerves and skin that is supplied by the dorsal cutaneous nerves.

Superficial Surgical Dissection

Separate the longitudinally running fibers of the palmar aponeurosis by blunt dissection, by opening a closed hemostat so that the dissection is

carried out parallel to, rather than across, the main neurovascular bundles of the palm (see Fig. 5-78B). Proceed deeper onto the proximal end of the fibrous flexor sheath. At this level, the proximal (A1) pulley is visible. Incise the pulley longitudinally to reveal turbid fluid or, more rarely, frank pus (see Fig. 5-78C). If turbid fluid is found, make the second skin incision and deepen it, coming down dorsal to the digital nerves and vessels. Incise the fibrous flexor sheath at the distal end of the middle phalanx.

This second incision allows through-and-through irrigation to be carried out, if it is required (see Fig. 5-78A).

Dang

Nerves and Vessels

The digital nerves and vessels are at risk in both incisions. If the skin incision in the finger is made too far in a volar direction, it may threaten the neurovascular bundle. The bundle is safe as long as the skin incision remains just dorsal to the dorsal end of the proximal and distal interphalangeal creases (see Fig. 5-78 and Midlateral Approach to the Flexor Sheaths, page 224).

Because the skin palmar incision crosses the neurovascular bundles at right angles, and because the bundles lie immediately deep to the palmar aponeurosis, the bundles may be damaged by overzealous incision of the skin. Separating the fibers of the palmar aponeurosis by blunt dissection in the line of the fibers avoids damage to the nerves.

How to Enlarge the Approach

The approach cannot be enlarged effectively. Infections in the radial or ulnar bursae require a separate incision.