Open Release of Pediatric Trigger Thumb
Authors: Farr Sebastian 
Published: April 2022

Background:
Open release of a trigger thumb has been shown to be the most reliable option to restore full interphalangeal (IP) joint extension and thus normal thumb-joint motion in children
1
. The aim of this procedure is to restore free gliding of the flexor pollicis longus (FPL) tendon in its canal in children with fixed IP joint flexion contractures or those in whom nonoperative treatment modalities have failed.

Description:
The surgical procedure is easy to perform and straightforward; however, attention must be given to several details in order to avoid surgical failure and complications. General anesthesia is required for this procedure. The extremity is prepared and draped in a sterile fashion with the patient in the supine position, and a tourniquet is utilized to facilitate surgical dissection. A transverse incision is gently made just adjacent to the thumb metacarpophalangeal (MP) flexion crease, above the so-called Notta nodule. The ulnar neurovascular bundle is retracted to the side, and the Notta nodule, a local enlargement of the FPL tendon
2
, is visualized at the A1 pulley. The pulley is incised longitudinally to allow for full IP joint extension. After verification of full passive motion, the tendon is inspected for any further abnormalities. Then, the tourniquet is released, and the wound is closed with absorbable sutures. We recommend the use of local anesthetics for postoperative pain control. In cases of a trigger thumb stuck in extension, full tenodesis flexion of the IP joint combined with smooth, full passive extension confirms a complete release.

Alternatives:
Nonoperative treatment modalities mainly include watchful waiting for spontaneous resolution
3
, occupational therapy (i.e., passive exercising)
4,5
, and splinting therapy
6
. However, prolonged stretching and splinting may move the nodule to a point distal to the stenotic pulley, thus resulting in a trigger thumb locked in extension with a loss of IP flexion. Alternative surgical treatment techniques involve percutaneous trigger thumb release or open release with alternative surgical approaches (e.g., an oblique or Brunner incision)
7,8
.

Rationale:
Several reports have shown that open release of a trigger thumb leads to the most reliable outcomes in terms of achievement of range of motion and complications
1,9,10
. The main advantage of this procedure is the perfect visualization of the FPL tendon beneath the stenotic A1 pulley, which allows for a complete A1 release with clear vision. Such visualization cannot be provided with use of percutaneous techniques, which position the neurovascular bundle in potential danger for iatrogenic injury or may lead to incomplete pulley release
8
. Moreover, the use of this procedure allows parents to avoid the prolonged therapy and splinting associated with nonoperative treatment. Formal rehabilitation is usually not necessary postoperatively.

Expected Outcomes:
Open release of a trigger thumb is a safe and reliable option that leads to full range of motion in 95% of children, which is substantially higher than for nonoperative treatment with therapy (55%) and splinting (67%)
1
. Even delayed open release may provide satisfactory outcomes
9
. Although spontaneous resolution without surgery has been reported in 63% of cases
3
, patients with a flexion contracture of >30° showed spontaneous resolution in only 2.5% of cases
10
. Furthermore, the open surgical technique has been shown to have a lower rate of complications (around 3.4%)
11
compared with percutaneous techniques, which showed a 3.29 times increased risk of recurrence
12
and relevant injury to the neurovascular bundle
8
. If the A1 is fully divided, recurrence is highly unlikely. Postoperative rehabilitation is very quick following open release of a trigger thumb because closure under local anesthesia provides a painless postoperative course, wounds heal within a few days, and children are allowed to resume play immediately once a bandage is applied.

Important Tips:

The use of surgical loupes is of paramount importance to safely perform this procedure.Place the skin incision adjacent but not directly onto the palmar MP flexion crease for better scar formation.Divide the skin very gently because the A1 pulley is located directly under the skin, and the FPL and radial nerve can be harmed easily. Retract the ulnar neurovascular bundle aside so as to allow for safe preparation until A1 division.Divide the A1 pulley until the Notta nodule on the FPL can safely glide distally into full IP extension. In some cases with large, distally-sitting nodules, the pulley incision must be extended distally into the oblique bundle.A sign that the entire A1 pulley is released is seeing the corner formed by the distal edge of the pulley and the longitudinal cut in the pulley. Additionally, the cut halves of the fully released pulley will rest completely in the sagittal plane of the thumb, no longer converging over the FPL tendon.Tight bands can exist proximal and distal to the A1 pulley and should be released as well if present.Check for a tight IP volar plate following A1 division, which may require postoperative splinting.For thumbs stuck in extension, tenodesis can be utilized to verify complete A1 release.Utilize absorbable sutures, local anesthesia, and a bulky dressing to allow a comfortable postoperative course.

Acronyms and Abbreviations:

IP = interphalangealMP = metacarpophalangealFPL = flexor pollicis longusROM = range of motionANOVA = analysis of variance