The Effect of Peroneal Muscle Strength on Functional Outcomes After the Modified Broström Procedure for Chronic Ankle Instability

Abstract

Category: Sports Introduction/Purpose: Although the peroneal muscle is known to be a major dynamic lateral stabilizer of the ankle, few informations are available regarding the changes of muscle strength and relationship with the outcomes after lateral ligaments repair surgery. The purpose of this study was to identify the effects of peroneal strength on the validated functional outcome measures after the modified Broström procedure(MBP) for chronic ankle instability. Methods: Forty-one patients (41 ankles) underwent MBP using suture anchors were eligible and followed up to 2 years postoperatively. Functional evaluation consisted of the Foot and Ankle Outcome Score(FAOS), Foot and Ankle Ability Measure(FAAM). The changes of peroneal strength were evaluated using isokinetic dynamometer. Differences in the functional outcomes between the 3 groups divided according to recovery rate of peroneal strength were analysed. Results: Peak torque and total work for eversion in 60º/sec angular velocity significantly improved from a mean 8.1 Nm, 5.2 Nm preoperatively to 11.4 Nm, 6.9 Nm at postoperative 2 years, respectively (P < .001, P = .038). Deficit ratio of peak torque for eversion significantly improved from a mean 38.6% to 17.4%, and a significant side to side difference was found (P = .011). There were no significant differences in FAOS, FAAM, and measurements of stress radiograph between the 3 groups. Conclusion: Although restoration of peroneal strength postoperatively was about 82.6% of unaffected ankle, patient-reported function in daily and sport activities were satisfactorily improved. Postoperative isokinetic strength of the peroneus demonstrated no statistically significant effects on the functional outcomes after MBP.