Outcomes Following Retrograde Intramedullary Threaded Nail Fixation of Distal Ulnar Neck Fractures

Purpose: Unstable fractures of the distal ulna present a clinical challenge. The purpose of this study was to describe the outcomes following fixation of unstable distal ulnar neck fractures via a retrograde intramedullary threaded nail (IMTN). Methods: We retrospectively identified patients at a single level 1 trauma center, between 2022 and 2025, who underwent surgical fixation of an unstable distal ulnar neck fracture with a retrograde IMTN. We included patients at least 1 year postinjury. Demographics, fracture characteristics, functional outcomes, radiographic outcomes, and complications were collected. Patients were grouped into 1-, 2-, and 3-year follow-up groups to determine rates of hardware removal. Current visual analog scale pain scores and patient-rated wrist evaluation scores were collected over the phone. Results: Seventeen patients were identified. The mean age was 65 years. Distal ulnar neck fracture morphologies included nine neck fractures with styloid fractures and eight extra-articular neck fractures. All were associated with an ipsilateral operative distal radius fracture. Average time to radiographic union was 8.5 ± 2.9 weeks and average ulnar variance was -0.55 mm ± 1.34 mm. One patient developed a nonunion secondary to IMTN back out. There were no occurrences of postoperative superficial-deep infection, dorsal sensory branch of the ulnar nerve injuries, or persistent-recurrent distal radioulnar joint instability. The average visual analog scale pain score was 0.29 ± 0.8, and the average patient-rated wrist evaluation score was 11.8 ± 7.9. Ulnar-sided wrist pain, localized to the distal radioulnar joint, was reported by two patients. Hardware removal rates were 5.9%, 0.0%, and 0.0% at 1 year, 2 years, and 3 years, respectively. Conclusions: A rare complication of retrograde IMTN fixation of a distal ulnar neck fracture is nonunion with subsequent implant back-out. The present cohort demonstrated a low removal of hardware rate and an absence of insertion-site pain, suggesting a potential advantage of intramedullary implant tolerability for the treatment of distal ulnar neck fractures. Type of study/level of evidence: Therapeutic IV.