Trans-olecranon fracture posterior dislocation: a novel type of elbow injury

BACKGROUND: Based on our experiences, we found that a kind of elbow injury is characterized by an olecranon fracture accompanied by elbow joint posterior dislocation with the proximal radioulnar joint intact. The aim of this study was to better define this kind of severe elbow instability, which has not been previously reported. METHODS: We retrospectively analyzed all patients with olecranon fractures who were treated at our institution from January 2013 to April 2021. Data on these patient demographics, injury characteristics, preoperative and postoperative imaging, surgical management, and outcomes were recorded and analyzed. We also made the inclusion criteria and exclusion criteria. RESULTS: A total of 309 patients were diagnosed olecranon fractures in our institution, and ten patients met the inclusion criteria, 9 males and 1 female, with an average age of 40.6 ± 12.7 years (26–68 years). Eight patients (80%) were comminuted, and two were oblique olecranon fracture. Nine patients (90%) suffered coronoid process fractures, eight fractures were type III, and one was type II. Eight patients (80%) suffered radial head fractures, seven fractures were type II, and one was type III. All patients suffered lateral collateral ligament complex injury. All patients underwent surgical management and were followed up on average for 15.8 ± 3.2 months (12–20 months). The motion of the elbow and functional outcome were evaluated with several methods. The mean arc of the elbow movement was 131.6° ± 6.0° (124°–140°), and the mean arc of the forearm rotation was 158.5° ± 17.8° (128°–180°). Nine patients’ functional results according to the Mayo Elbow Performance Score (MEPS) were excellent with a mean score of 96.5 ± 5.3 points (85–100 points), and another was good. The mean score according to the Broberg and Morrey functional rating index was 98.8 ± 2.5 points (92–100 points), nine patients were excellent, and another was good. The mean Disabilities of the Arm, Shoulder, and Hand (DASH) score was 0.75 ± 1.2 points (0–3.3 points). CONCLUSIONS: Trans-olecranon fracture posterior dislocation is a rare injury and has unique characteristics, and it is a kind of complex elbow instability involving the coronoid process and radial head fractures. After bony structure is restored, the repairment of lateral collateral ligament complex is also important to the stability of the elbow joint. Correct understanding of this kind of injury and reasonable treatment plan can achieve good function.