Comparison of Prevalence of Arthroscopically Detected Intra-Articular Pathologies Between Supination and Pronation Type Ankle Fractures

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Category: Arthroscopy; Ankle Introduction/Purpose: Ankle fractures are among the most common fractures of the lower extremity. Most unstable ankle fractures have good outcomes following operative fixation; however, residual pain and swelling are not uncommon despite anatomical bone reduction. Untreated associated injuries, including syndesmotic injury, deltoid ligament injury, and osteochondral injury, are potential causes for suboptimal outcomes. These pathologies are often underappreciated. The Lauge-Hansen classification is used to categorize fractures based on the mechanism of injury and thus has the potential to predict intra-articular pathology. To date, there is limited literature reporting the comprehensive prevalence of arthroscopically diagnosed intra-articular pathologies in acute ankle fractures based on the mechanism of injury. This study aims to report the prevalence of each intra-articular pathology between different fracture patterns. Methods: A retrospective database review was conducted on 203 patients with rotational ankle fractures who underwent arthroscopic-assisted open reduction and internal fixation for unstable acute ankle fractures between 2016 and 2023. Patients with open fractures, pilon fractures, delayed treatment, and children with open physes were excluded from the study. The patients were categorized into groups according to the Lauge-Hansen classification: Supination-Adduction (SA), Supination-External Rotation (SER), Pronation-External Rotation (PER), and Pronation-Abduction (PA). Syndesmotic injuries were determined by the arthroscopic drive-through sign with a 3mm shaver, while deltoid ligament injuries and osteochondral injuries were identified using arthroscopic visualization. Results: There were 3 patients (1.48%) with SA fractures, 143 patients (70.44%) with SER fractures, 6 patients (2.96%) with PA fractures, and 51 patients (25.12%) with PER fractures. The prevalence of arthroscopically diagnosed syndesmotic instability following malleoli fixation was extremely high in most fracture patterns except the SA mechanism (PER: 98.04%, PA: 100%, SER: 89.51%, SA: 33.33%). The prevalence of osteochondral injury was higher in pronation-type injuries than supination-type injuries (73.78% vs 53.9%, p=0.03). Deltoid ligament injury was found in 56.74% of SER fractures and 68.42% of PA/PER fractures. Conclusion: The prevalence of intra-articular pathologies in ankle fracture was higher in pronation-type injuries. However, the prevalence of these pathologies, especially syndesmotic instability, in SER fracture patterns was also alarming. The authors advocate for routine ankle arthroscopy simultaneously with ankle fixation to provide adequate treatment and predict prognosis.