PURPOSE: Longitudinal radioulnar dissociation is a triad of injuries consisting of distal radioulnar joint disruption, interosseous ligament complex (IOLC) tear, and radial head fracture. This renders the forearm longitudinally unstable, resulting in proximal migration of the radius and ulnar-sided wrist degeneration. We hypothesized that reconstruction of the central band of the IOLC in cadaver forearms using a Mini-TightRope suture-button construct would restore native forearm stability. METHODS: We implanted 8 fresh-frozen cadaver arms with steel beads into the distal radius and ulna, mounted them on an MTS machine, and cyclically loaded them from 13 N distraction to 130 N compression. Bead motion was recorded fluoroscopically and analyzed using Image-Pro Express software. We measured distal ulnar forces using strain gauge transducers. Longitudinal radioulnar dissociation injuries were created by radial head excision and complete IOLC and triangular fibrocartilage complex disruption. At each stage, arms were tested with and without a radial head implant. We reconstructed the central band of the IOLC using a Mini-TightRope and tightened until the distal radioulnar joint was reduced fluoroscopically. We used multiple-comparison analysis of variance with Tukey's Honestly Significant Difference test for statistical analysis. RESULTS: The intact arms had an average radioulnar axial displacement of 0.7 +/- 0.8 mm and distal ulnar impaction force of 16.7 +/- 11.1 N (per 100 N of axial load on the forearm). After destabilization, the radioulnar displacement increased to 10.7 +/- 3.9 mm (p < .001) and ulnar load increased 312%, to an average of 52.2 +/- 25.7 N (p < .001). After IOLC reconstruction, average displacement decreased to 2.2 +/- 0.9 mm with a distal ulnar load of 19.05 +/- 13.5 N (not significantly different from intact arms). CONCLUSIONS: In this cadaveric study, Mini-TightRope IOLC reconstruction with or without a radial head prosthesis significantly reduced distal ulnar impaction forces to that of the native forearm, while limiting radioulnar displacement to near-anatomic levels.
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