Varus-Tilted Distal Tibial Plafond Is a Risk Factor for Recurrent Ankle Instability After Arthroscopic Lateral Ankle Ligament Repair

Abstract

Background: Although varus-tilted distal tibial deformity is an established risk factor for chronic lateral ankle instability (CLAI), no studies have reported whether this deformity influences ankle instability after arthroscopic lateral ankle ligament repair (ALLR) for CLAI. Methods: A total of 57 ankles from 57 patients who underwent ALLR for CLAI were retrospectively analyzed. Tibial articular surface (TAS) angles were measured on preoperative plain radiograph. After 12 months of follow-up, recurrent ankle instability and talar tilt angles on stress radiograph were evaluated as outcomes. Relationships between the TAS angle and these outcomes were assessed. Results: Recurrent ankle instability was observed in 10 ankles. The TAS angles of patients with recurrent instability were significantly lower (85.2 degrees vs 87.9 degrees). The receiver operating characteristic curve analysis revealed that the cutoff value of TAS angle for recurrent instability was 86.2 degrees. Based on this cutoff value, our patients were divided into 2 groups: low-TAS and high-TAS group. Univariate and multivariate analysis revealed that low TAS was an independent risk factor for recurrent ankle instability and greater postoperative talar tilt angles. Conclusion: Varus-tilted distal tibial plafond appears to be a risk factor for recurrent ankle instability after ALLR.