Postoperative Isokinetic Evertor Strength is Important Prognostic Factor Following Arthroscopic Modified Brostrom Procedure in Chronic Ankle Instability

Abstract

Category: Sports; Arthroscopy Introduction/Purpose: Isokinetic eccentric muscular weakness has been considered an etiological factor for CAI by previous studies. It is widely accepted that initial management should be nonoperative in patients with CAI. In case of failure, however, surgical treatment may be considered. Even though, there were some studies evaluate the isokinetic muscle strength in sprain or CAI patients, there was few studies that investigate the isokinetic muscular result after arthroscopic modified brostrom (MBP) for CAI. The objective of this study was to evaluate the isokinetic ankle strength at 2 years after MBP and determine the effect of isokinetic ankle strength on clinical outcome. Methods: Between 2018 and 2019, we performed a retrospective review of 74 patients who underwent arthroscopic MBP and followed up to 2 years postoperatively with isokinetic strength test. Functional evaluation consisted of the Foot and Ankle Outcome Score (FAOS). Isokinetic peak torque values of dorsiflexion, plantarflexion, eversion and inversion at 2 angular velocities (30°/s and 120°/s) were measured in the injured and normal ankles. Paired t-test were performed to evaluate postoperative improvement of weakness (ratio of impaired side/intact side) of ankle strength, and linear regression test were performed for their correlation to clinical outcome using SPSS 20.0. Results: All clinical scores and isokinetic muscle strength were improved postoperatively. All units in FAOS except symptom unit corelated positively to the postoperative inversion strength (p<0.05, all). In addition, sports unit in FAOS was corelated to postoperative plantarflexion strength (p<0.05). Conclusion: Functional scores and all isokinetic muscle strength were significantly improved after arthroscopic MBP. However, the weakness of postoperative isokinetic eversion strength was still negative factor for clinical outcome after surgery.