Background: The rarity and complexity of trans-ulnar basal coronoid fracture-dislocations pose significant challenges in treatment. This study aimed to categorize these fractures based on coronoid fracture patterns and propose tailored surgical approaches for each type. Additionally, we evaluated the functional and radiological outcomes among the patients managed using our treatment algorithm. Methods: A total of 19 patients who underwent open reduction and internal fixation for trans-ulnar basal coronoid fracture-dislocations between March 2018 and October 2022 were enrolled in this study. These patients were classified based on the coronoid fracture patterns associated with olecranon fractures: type 1 involved anteromedial facet (AMF) fractures, type 2 encompassed coronoid base and body fractures, and type 3 involved a combination of types 1 and 2. We made a midline longitudinal dorsal incision to facilitate the provisional fixation of the olecranon fragment to the distal metaphysis using a locking plate. Subsequently, we employed the over-the-top (type 1) and Taylor-Scham (type 3) approaches for direct coronoid process fixation with buttress plating. Type 2 fractures were approached via medial fascial exposure from the posterior ulnar cortex or through the olecranon fractures, and subsequently fixed with miniplates and screws. Bony union and joint articulation were assessed via plain radiographs, and functional outcomes were evaluated using range of motion and the Mayo Elbow Performance Score. Results: Among the 19 patients, 3 had type 1 fractures, 14 had type 2 fractures, and 2 had type 3 fractures. All fractures exhibited solid osseous union without subluxation or dislocation. The average flexion and extension arc was 119.47 degrees +/- 20.88 degrees, with a mean flexion of 127.37 degrees +/- 13.37 degrees and an average flexion contracture of 7.89 degrees +/- 10.04 degrees. The average Mayo Elbow Performance Score was 82.63 +/- 12.51 points. Qualitatively, patient outcomes were excellent in 5 patients, good in 9, and fair in 5. Conclusions: Most of our patients presented with easily approachable coronoid base and body fractures. However, in AMF fractures of the coronoid process, a direct medial approach is required for buttress plating. We believe our study helps provide useful guidelines for making appropriate decisions in trans-ulnar basal coronoid fracture-dislocations .
