Category: Sports; Ankle; Arthroscopy Introduction/Purpose: The modified Brostrom (MB) procedure has long been the mainstay for the treatment of chronic lateral ankle instability (CLAI) despite concerns about the strength of the repair. Recently, the InternalBraceTM (IB) has emerged as augmentation for this repair. The clinical benefit of such augmentation has yet to be established. The purpose of this study is to determine whether or not IB augmentation provides an advantage over the traditional MB. The preliminary results of this study are presented. Methods: Patients were identified for inclusion in the study based on indications for primary lateral ligament reconstruction for CLAI, age over 18, and able to provide informed consent. Exclusion criteria included pregnancy, cognitive disability, concomitant bony correction, inadequate soft tissue for MB, or prior ankle surgery affecting the lateral ligament complex. Preliminary outcome measures included complication rates, ability to participate in an accelerated rehabilitation protocol, and time to return to pre- injury level of activity. Complications were identified during post-operative clinical evaluations. Conversion from accelerated to traditional rehabilitation protocol was determined by patient’s self-reported ability to participate or VAS >= 5 per the physical therapist. Patients were contacted every 2 weeks from 6 to 26 weeks post-operatively to determine return to pre-injury level of activity. Results: 119 patients with CLAI who met criteria were enrolled in the study and randomized to the MB (59 patients) or IB (60 patients) treatment arm. At six months 11 patients (18.6%) of the MB arm and 4 patients (6.7%) of the IB arm were lost to follow up. 6/48 patients in the MB group and 2/56 patients in the IB group had not returned to preinjury activity level (p =.115). The complication rate was 8.5% in the MB group versus 1.7% in the IB Group. 4 patients in the MB group failed to complete the accelerated rehabilitation protocol versus 1 in the IB group. Average time to return to pre-injury level of activity was 17.6 weeks after MB and 13.2 weeks after IB (p<0.001). Conclusion: Preliminary results from this multicenter, prospective, randomized trial suggest that IB augmentation allows for faster return to pre-injury level of activity than MB alone. IB augmentation may support successful accelerated rehabilitation. IB augmentation did not add any additional risk of post-operative complication. Further areas of investigation include longer-term follow up and patient reported outcome scores.