Concomitant Syndesmotic Instability and Medial Ankle Instability Are Risk Factors for Unsatisfactory Outcomes in Patients With Chronic Ankle Instability

Purpose: To determine whether concomitant chronic syndesmotic injury or chronic medial ankle instability is associated with unsatisfactory outcomes in patients with chronic lateral ankle instability (CAI). Methods: We conducted a retrospective review of prospectively collected data from 276 male military patients with CAI who had undergone a modified Brostrom procedure between May 2007 and March 2010 and had been followed up for a mean of 26.7 months (range, 22 to 41 months). We evaluated clinical outcomes using American Orthopaedic Foot & Ankle Society ankle-hindfoot, visual analog scale, and ankle functional satisfactory scale scores. Possible associations with concomitant instability were reconstructed and investigated using the Pearson correlation coefficient and multivariate logistic regression analysis. Results: Of the 236 patients with satisfactory outcomes, 19 (8%) had medial ankle instability and 13 (6%) had syndesmotic instability; in contrast, of the 40 patients with unsatisfactory outcomes, 14 (35%) had medial ankle instability and 12 (30%) had syndesmotic instability. The mean American Orthopaedic Foot & Ankle Society scores for patients with satisfactory and unsatisfactory outcomes increased from 68.1 to 92.8 (P < .001) and from 65.9 to 76.8 (P < .001), respectively. The mean visual analog scale scores for the groups with satisfactory and unsatisfactory outcomes decreased from 5.8 to 2.1 (P < .001) and from 6.2 to 4.8 (P < .001), respectively. The mean ankle satisfaction score was 27.8 for patients with satisfactory outcomes and 18.7 for those with unsatisfactory outcomes (P < .001). Multivariate logistic regression analysis showed a 4-fold higher risk of dissatisfaction (95% confidence interval [CI], 0.81 to 20.07; P ¼ .0880) with CAI and syndesmotic instability, a 3.8-fold higher risk (95% CI, 0.96 to 15.07; P ¼ .0576) with CAI and medial ankle instability, and an 11.7-fold higher risk (95% CI, 2.60 to 52.70; P ¼ .0014) with CAI and both syndesmotic and medial ankle instability. Conclusions: Chronic syndesmotic instability and chronic medial ankle instability are significantly associated with unsatisfactory outcomes in patients with CAI. Level of Evidence: Level IV, therapeutic case series.