5: Surgical Treatment of Trigger Digits

Published on 19/04/2015 by admin

Filed under Surgery

Last modified 22/04/2025

Print this page

This article have been viewed 2191 times

Procedure 5 Surgical Treatment of Trigger Digits

Brent M. Egeland, Sandeep J. Sebastin, Kevin C. Chung

See Video 2: Surgical Treatment of Trigger Digits

Examination/Imaging

Clinical Examination

The patient is examined for a palpable nodule at the level of A1 pulley. The patient may be unable to flex the finger or experience a catching when the finger flexes as the enlarged tendon passes through the A1 pulley (Fig. 5-1).

The grade of triggering should be recorded for follow-up purposes (Table 5-1). One should look for tenderness over the A1 pulley and a palpable nodule. In long-standing triggering, a flexion contracture of the PIP joint may be present, and the degree of contracture should be noted.

The most frequently involved digit is the ring finger, followed by the thumb and the long, small, and index fingers. Patients who present with primary index finger trigger must be evaluated for associated conditions like diabetes and rheumatoid arthritis.

In patients with rheumatoid arthritis, one must carefully differentiate between the snapping observed in fingers with early swan-neck deformity and the catching seen in trigger finger. The snapping finger is due to the sudden return of the lateral bands from a dorsal to a palmar location over the condyle of the proximal phalanx as the patient actively corrects the hyperextension deformity. Occasionally triggering may be due to flexor tendon nodules getting caught under the carpal tunnel.

Rarely, a locked metacarpophalangeal (MCP) joint can be confused with a trigger finger. A trigger finger primarily affects the interphalangeal joints and is usually gradual in onset, in contrast to the sudden onset of MCP joint locking. MCP joint locking usually results from collateral ligament injury, sesamoid, or osteophyte entrapment.

Congenital trigger thumb most commonly presents with a fixed flexion deformity, and less commonly with triggering. A characteristic nodule (Notta node) can be palpated on the flexor pollicis longus (FPL) tendon at the region of the A1 pulley. This can help differentiate congenital trigger thumb from other clasped thumb deformities.

Congenital trigger finger is a distinct entity related to abnormal thickening of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP), calcifications or granulations within the tendons, or abnormal relationship of the tendons at the FDS decussation. The common sites for triggering in a congenital trigger finger are the A1 pulley, the FDS chiasm, and the A3 pulley (Fig. 5-2).

FIGURE 5-1

Table 5-1 Grading of Trigger Digits

Grade I	Before triggering	History of triggering, but not demonstrable on examination
Grade II	Active	Demonstrable triggering, but patient can actively overcome the trigger
Grade III	Passive	Demonstrable triggering, but patient cannot actively overcome trigger
• IIIA	• Extension	• Locked in flexion and needs passive extension to overcome trigger
• IIIB	• Flexion	• Locked in extension and needs passive flexion to overcome trigger
Grade IV	Contracture	Demonstrable trigger with flexion contracture of posterior interphalangeal joint

FIGURE 5-2

Imaging

Imaging is most often not necessary. Ultrasound examination can be useful when diagnosis requires confirmation. A radiograph may be useful in a patient with a long-standing flexion contracture to determine the condition of the PIP joint.

Surgical Anatomy

Triggering occurs at the proximal edge of the A1 pulley for the fingers and the thumb.

The proximal edge of the A1 pulley for the small and ring fingers is in line with the distal palmar crease; for the long finger, it is midway between the distal and proximal palmar creases; and for the index finger, it is in line with the proximal palmar crease. The proximal edge of the A1 pulley of the thumb is at the level of the MCP joint crease.

Biomechanical studies have shown that the integrity of the A2 and A4 annular pulleys is most important to prevent bowstringing in the fingers. Therefore, it is important to prevent injury to the A2 pulley during division of the A1 pulley. Similarly, the oblique pulley in the thumb prevents bowstringing and should be preserved.

Positioning

The patient lies supine on the operating table with the affected arm placed on a hand table.

The procedure is performed under tourniquet control under local anesthesia.

Exposures

A 1-cm transverse incision is made in line with the distal palmar crease for the long, ring, and small fingers and at the proximal palmar crease for the index finger (Fig. 5-3).

A 2-cm chevron-shaped apex radial incision is made over the MCP joint crease (a more extensile incision to visualize the digital nerves) for release of thumb trigger.

The subcutaneous fat is gently spread with scissors to expose the tendon sheath and the A1 pulley. Two Ragnell retractors are held by the assistant to maintain visualization (Fig. 5-4).

FIGURE 5-3

FIGURE 5-4

Pearls

Bruner zigzag incisions are used in patients with rheumatoid arthritis because they may need a wider exposure for tenosynovectomy. Similarly, the zigzag incision is used in pediatric trigger finger to the level of the PIP joint to expose the A2 pulley and FDS decussation.

Pitfalls

The radial digital nerves to the thumb and the index finger are most at risk for injury because they take an oblique course from ulnar to radial close to the A1 pulley. The thumb radial digital nerve is also very subcutaneous and can be accidentally transected with a deep skin incision (Fig. 5-5).

FIGURE 5-5

Procedure

Primary Trigger Finger Release

Step 1

The A1 pulley is exposed with gentle traction of the soft tissues and incised with a no. 15 blade (Fig. 5-6).

Once identified and partially divided, the scissors is used to complete the sheath division (Fig. 5-7).

Any excessive synovial tissue should also be excised, if encountered.

A tendon hook is used to provide traction on the FDS, and then the FDP, ensuring that it results in smooth flexion of the PIP joint and distal interphalangeal (DIP) joint, respectively. It is advisable to ask the patient to move the fingers actively to determine whether there is any limitation of tendon excursion.

FIGURE 5-6

FIGURE 5-7

Step 1 Pearls

The scissor tips should be placed parallel to the course of the tendon sheath during soft tissue dissection to avoid injury to the neurovascular bundles.

Patients with rheumatoid arthritis and trigger fingers need flexor tenosynovectomy. A1 pulley release may be done only after tenosynovectomy has failed to relieve the trigger. The release of the A1 pulley may contribute to the MCP joint ulnar drift deformity, especially for the index and long fingers, because of the oblique line of pull of the long flexors for these digits. Because of this tendency, some surgeons recommend resection of one slip of the FDS to provide more space for passage of the FDP, as opposed to an A1 pulley release.

Step 2

The tourniquet is released and hemostasis achieved using bipolar electrocautery.

The skin is closed with interrupted 4-0 nylon sutures.

A soft, lightly compressive bandage is applied.

Motion is begun immediately.

Procedure

Congenital Trigger Finger

Congenital trigger finger is rare. It is usually due to an enlarged tendon or abnormal anatomic relationship of the FDS and FDP at the FDS decussation. Treatment is directed at specific intraoperative findings but may include not only A1 pulley release but also partial resection of the FDP or FDS tendon.

Step 1

Bruner incisions are made over the A1 and A2 pulleys (Fig. 5-12).

The A1 pulley is visualized and divided as described previously (Fig. 5-13).

FIGURE 5-12

FIGURE 5-13

Step 2

Intraoperative traction is applied to the flexor tendons, and they are observed for triggering—most commonly at the FDS decussation or under A2 (Fig. 5-14).

If triggering is observed, the focally thickened tendon is partially shaved to decrease the bulk, and the FDS decussation is opened partially to permit easier movement to the FDP through the decussation.

If triggering is not yet completely resolved, partial division of A2 may be required (Fig. 5-15).

FIGURE 5-14

FIGURE 5-15

Step 3

The tourniquet is released and hemostasis achieved using bipolar electrocautery.

The incision is closed with 5-0 plain catgut suture.

A soft, lightly compressive bandage is applied.

Bae DS, Sodha S, Waters PM. Surgical treatment of the pediatric trigger finger. J Hand Surg [Am]. 2007;32:1043-1047.

This retrospective study evaluated 23 pediatric trigger fingers treated over a 10-year period with division of the A1 pulley and resection of a single slip of the flexor digitorum superficialis. Ninety-one percent of fingers had complete resolution of the triggering. There were no complications using the described treatment. (Level IV evidence)

Marks MR, Gunther SF. Efficacy of cortisone injection in treatment of trigger fingers and thumbs. J Hand Surg [Am]. 1989;14:722-727.

One hundred consecutive patients with trigger fingers were treated with steroid injection alone. Eighty-four percent of the patients had a favorable response to one injection, and 91% to two injections. This study indicated that steroid injection is quite effective for treating trigger fingers. (Level III evidence)

Wilhelmi BJ, Snyder N, Verbesey JE, et al. Trigger finger release with hand surface landmark ratios: an anatomic and clinical study. Plast Reconstr Surg. 2001;108:908-915.

This study evaluated the anatomic relationships of the A1 pulley to surface landmarks in the hand in 256 fingers. The study demonstrated that the distance from the proximal interphalangeal joint crease to the palmar digital crease is nearly identical to the distance from the palmar digital crease to the proximal edge of A1. (Level V evidence)

Related

Operative Techniques Hand and Wrist Surgery