Open Double Mallet Lesion of the Ring Finger with Concomitant Little Finger Fracture: A Case Report

Background and Clinical Significance: Mallet finger is a common injury of the extensor mechanism at the distal interphalangeal (DIP) joint; however, open double mallet lesions are rare and may present a complex reconstruction challenge. Case Presentation: A 15-year-old male high school student who sustained an open injury to the left ring and little fingers after a high-energy buggy accident. The ring finger showed an open double mallet lesion in which the extensor tendon remained attached to a tiny avulsion fragment, and a separate dorsal base fragment was also present. The adjacent little finger had a concomitant open fracture with substantial soft tissue injury. Emergency surgery was performed on the day of the injury. For the ring finger, reduction of the tendon-attached avulsion fragment and separate dorsal base fragment was achieved using extension-block pinning, transarticular DIP pinning, and pull-out fixation over a volar button. For the little finger, cross-pinning was performed because the distal fragment was too small for stable non-transarticular fixation. Serial radiographs showed maintained alignment and progressive healing. At the final follow-up, 21 months after the injury, residual deformity and limitation of DIP motion remained; however, no infection, major skin complications, or nail deformity were observed. The little finger DIP joint became ankylosed, whereas some residual mobility remained in the ring finger DIP joint. Despite persistent functional limitations, the patient was able to continue school attendance and percussion-related activities. Conclusions: This case highlights that in an open double mallet lesion, disruption of both the tendon-attached fragment and its bony bed should be considered, and stabilization of the base may be useful in selected injury patterns before definitive tendon-side repair.