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.