Characterization of Pediatric Extension Trigger Thumb: An Insight Into a Rare Manifestation From a Single-Center Retrospective Cohort Analysis.

ABSTRACT

PURPOSE: This study aimed to evaluate the clinical features, possible etiology, and surgical outcomes of a rare manifestation of pediatric trigger thumb, extension trigger thumb (ETT). METHODS: We retrospectively reviewed a database of surgically treated trigger thumb patients and identified patients with ETT who had a minimum of 1-year follow-up after surgery from 2012 to 2018. We reviewed demographic and clinical information and recorded active and passive interphalangeal (IP) joint flexion before, during (intraoperative simulated active flexion), and after surgery (at final follow-up). These measurements were compared with those obtained from the unaffected thumb in unilaterally affected patients. RESULTS: Eighteen patients with ETT (21 affected thumbs) were identified. The incidence of ETT was 1%, with an increasing incidence through the years of the study. We found that 14 of 18 ETT patients had a history of fixed flexion trigger thumb managed with nonsurgical treatment. There was an average 38° ± 10° improvement in active IP joint flexion after surgery and at the final follow-up. For unilaterally affected patients, active IP joint flexion improved but did not reach the same level as on the unaffected side. CONCLUSIONS: Extension trigger thumb is a rare manifestation with a low incidence in pediatric trigger thumbs. Surgical release of the A1 pulley achieves a moderate improvement in flexion function at the IP joint. TYPE OF STUDY/LEVEL OF EVIDENCE Prognostic IV.