Arthroscopic findings and accuracy of preoperative diagnosis in patients with chronic lateral ankle instability

Purpose: Management of chronic lateral ankle instability (CLAI) has significantly evolved in recent years, driven by an increased awareness of ankle microinstability and advances in minimally invasive techniques. The purpose of this study was to report arthroscopic findings in ankles with CLAI treated arthroscopically according to contemporary concepts and to evaluate the diagnostic accuracy of preoperative assessments. We hypothesized that current indications for arthroscopic treatment of CLAI increasingly involve milder instability, which are associated with a lower incidence of intra-articular pathology than previously reported. Methods: A retrospective case series was conducted on 179 patients who underwent ankle arthroscopy for CLAI between 2020 and 2024. Ligamentous injuries were assessed both preoperatively (clinical examination and magnetic resonance imaging) and intra-operatively (arthroscopy), including anterior talo-fibular ligament's (ATFL) superior fascicle injuries, indicative of microinstability and lesions of the lateral fibulotalocalcaneal ligament complex (LFTCL: ATFL inferior fascicle + calcaneofibular ligament [CFL]), indicative of macroinstability. Intra-articular lesions such as soft tissue impingement, osteophytes, loose bodies and osteochondral lesions were also assessed. Preoperative and intra-operative diagnosis were then compared. Results: All patients had ATFL injuries. Isolated ATFL's superior fascicle injuries were the most frequent (73.2%), while combined ATFL's superior fascicle and LFTCL injuries accounted for 26.8%. Within LFTCL injuries, ATFL's inferior fascicle was affected in isolation in 21.2% and combined with the CFL in 5.6%. Concomitant intra-articular lesions were identified in 54.7%, most commonly soft tissue impingement (43.6%), followed by osteochondral lesions (15.1%). Concordance between preoperative and intra-operative diagnosis was poor (κ = 0.08, absolute agreement 24.2%). Conclusion: Isolated injury of ATFL's superior fascicle is the most frequently observed ligament lesion during arthroscopic treatment of CLAI. Associated intra-articular pathologies are present in 54.7% of cases. The limited concordance between preoperative and intra-operative diagnoses in this surgically indicated cohort underscores the role of arthroscopy in the accurate identification and management of intra-articular lesions. Level of Evidence: Level III, retrospective comparative study.