Complications in Surgery of the Thumb

Overview

Pediatric trigger thumb most commonly presents with a fixed flexion deformity of the thumb interphalangeal (IP) joint. Pediatric trigger thumb is over 10 times more common than pediatric trigger finger, and is a distinct entity that is considered and treated differently than adult or pediatric trigger finger. Pediatric trigger thumb most commonly presents early in childhood at approximately 2 years of age. The pathologic anatomy of pediatric trigger thumb includes formation of a nodule (Notta’s nodule) in the flexor pollicis longus (FPL) tendon and thickening of the tendon sheath. This results in a size mismatch between the FPL tendon and the first annular (A1) pulley, which disrupts normal tendon gliding. The exact pathophysiologic etiology remains unknown. This is an acquired rather than a genetic condition.

Rates of spontaneous resolution vary widely, ranging from 0% to 66%. Nonoperative interventions include passive stretching, splinting, and casting, but it is unclear whether these interventions are any more effective than observation alone. Surgical management is generally indicated for failed conservative treatment or a fixed flexion deformity, but there is no definite consensus on the age at which surgery is ideally performed. Surgical treatment is open release of the A1 pulley of the thumb, and it has been shown to be effective in restoring IP joint range of motion. The reported complication rate of open surgical release is 1%, and potential complications include injury to the thumb nerves or arteries, inadequate pulley release with persistent or recurrent symptoms, and wound complications including surgical site infection.

Preoperative Considerations

Preoperative physical examination typically demonstrates a painless fixed flexion deformity of the thumb IP joint with a palpable nodule at the volar aspect of the metacarpophalangeal (MCP) joint crease (Notta’s nodule). There may be compensatory thumb MCP hyperextension in longstanding cases of a fixed IP joint flexion. Less frequently the child is able to actively trigger the thumb with flexion and extension. Rarely, the thumb may be stuck in extension. Both thumbs are examined, as bilateral involvement occurs in approximately 25% of cases. Hutchinson et al. found that bilateral thumb involvement increased the risk for undergoing surgery by 138% and was associated with a poorer prognosis. Radiographs are recommended if there is a history of trauma, but imaging is generally not recommended when the history and physical examination are consistent with trigger thumb. Pediatric trigger thumb is distinguished from other differential diagnoses, including congenital clasped thumb and thumb-in-palm deformity resulting from cerebral palsy or arthrogryposis.

Intraoperative Considerations

We approach the A1 pulley through a 1-cm transverse incision at the thumb MCP flexion crease, directly over the A1 pulley. Longitudinal incisions have a high risk of wound contracture and may result in a more visible scar, so we avoid this approach for improved aesthetic outcome. After the skin incision and superficial blunt dissection through subcutaneous tissue, the flexor tendon sheath is exposed. The radial digital nerve crosses the flexor tendon sheath at this level and is at risk with dissection, so it is identified and protected. Digital nerve injuries are exceedingly rare; however, the surgeon must be keenly aware of the course of the digital nerves to the thumb. The A1 pulley is sharply divided longitudinally under direct visualization. Passive extension of the thumb IP joint after A1 pulley release ensures that the thumb can achieve full extension with normal flexor pollicus longus tendon gliding. The proximal border of the oblique pulley is typically preserved to avoid tendon bowstringing but occasionally may be slightly released if the thumb does not easily extend. A locked trigger thumb is most easily released with direct extension pressure on the thumb, and when sufficient pulley has been released the thumb will extend fully. In patients with an intermittently catching trigger thumb, the distal level of complete release may be more difficult to discern and requires careful sheath preservation to avoid bowstringing. Percutaneous trigger finger release techniques described in the adult population are not utilized in pediatric trigger thumb used given the risk of incomplete A1 pulley release, flexor pollicus longus laceration, and iatrogenic neurovascular injury.

Postoperative Considerations

Wound complications were the most commonly reported complication in a 2014 systematic review of trigger thumb surgery. In Marek et al.’s series of 173 patients with 217 thumbs treated with surgical release, local wound complications including superficial infection, and wound dehiscence occurred in 2% of children treated with surgery, but responded to conservative wound management or oral antibiotics and did not require additional surgery. While some surgeons cast patients after trigger release, most utilize a soft dressing and early play activities. There is no indication that the type of wound closure or dressing affects the risk of wound complications. Although rare, persistence or recurrence of the flexion deformity can occur with incomplete pulley release. Some authors have questioned whether release of the A1 pulley alone is sufficient, with one study reporting that 11 out of 16 patients (69%) required release of an additional structure other than the sheath outside of the boundaries of the A1 pulley. Dunsmuir and Sherlock analyzed 200 trigger thumbs treated surgically and found an overall recurrence rate of 4%, with recurrence being more common in younger children. If recurrence occurs, revision surgery with complete pulley release is indicated. Notta’s nodule remains palpable immediately after surgery but does remodel over time, and preoperative family counseling helps to decrease concern about this issue.