Extensor Pollicis Longus Entrapment on CT in Acute Distal Radius Fracture May Be a Predictor of Tendon Rupture

Background: Extensor pollicis longus (EPL) rupture is a well-described complication after volar plate fixation of distal radius fractures. Although protrusion of screw tips through the dorsal cortex of the distal radius is likely the cause of a substantial proportion of EPL ruptures, it is probably not the sole cause for EPL rupture after distal radius fracture. The purpose of this study was to evaluate preoperative computed tomography (CT) scans of distal radius fractures to characterize the incidence of EPL damage at the time of injury.Methods: This retrospective study included adults with operatively treated distal radius fractures and a preoperative CT scan within 2 weeks of injury between January 1, 2017 and July 31, 2018. The cohort consisted of 96 wrists in 95 patients. The median age was 54 (interquartile range, IQR 38-64) years, 68% (65/95) were women, and median follow-up was 56 (IQR 22-61) months.Results: The fracture involved Lister's tubercle in 75% (72/96) of fractures. Of these 72 fractures, 11 had an EPL tendon entrapped by fracture fragments (18%). Within the cohort, two EPL injuries manifested clinically.Conclusion: We present evidence that not all EPL ruptures after Open reduction and internal fixation (ORIF) of the distal radius are related to prominent dorsal screws. Extensor pollicis longus entrapment in Lister's tubercle fracture fragments is relatively frequent and may be a potential contributor to tendon rupture. When a CT scan is obtained for the treatment of distal radius fractures, attention to the EPL and its relation to Lister's tubercle may be helpful to characterize the risk of late rupture.