Extensor pollicis longus tendon rupture caused by a displaced dorsal "beak" fragment of Lister's tubercle in distal radius fractures

Introduction Ruptures of the extensor pollicis longus (EPL) tendon are awell-known complication of distal radius fractures (DRF). There are a lot ofsuspected mechanisms, including mechanical friction, vascular impairment, injuryassociated with reduction, and local adhesion. However, there have been limitedreports about a closed rupture of the EPL tendon associated with a relativelylarge, displaced dorsal "beak" fracture fragment. We report about the managementoutcomes and clinical significance of closed ruptures of the EPL tendon causedby a displaced dorsal fracture fragment of beak-like appearance in DRF. Patients/Material and Methods Our study included 7 cases of a completeclosed rupture of the EPL tendon after open reduction internal fixation. Allcases showed a similar pattern involving a relatively large dorsal beak fragmentoriginating from Lister's tubercle, and we treated them with a palmar lockingplate within 7 days from the initial fracture without separate dorsal fragmentmanagement. All patients were diagnosed with a delayed EPL tendon rupture. Results The study included 5 female and 2 male patients. Mean patient agewas 59 years. In all cases we explored the extensor compartment III to verifythe exact cause of the EPL rupture. Six patients underwent an extensor indicistransfer and one patient underwent tendon grafting. Mean fragment width and length were 7.0 mm and 13.3 mm, respectively. Thefragments were dorsally elevated (mean, 2.4 mm) and distally displaced (mean,3.5 mm). At the last follow-up, the mean DASH score was 4.4. Mean thumb MP jointflexion and extension were 4 degrees and 62 degrees, respectively. Conclusion We support the possibility of EPL tendon rupture caused bydisplaced sharp Lister's tubercle fracture fragments.