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Reliability and Validity of Preoperative MRI for Surgical Decision Making in the Chronic Lateral Ankle Instability

      Introduction

      The anterior talofibular ligament (ATFL) is the most frequently affected ligament in chronic lateral ankle instability. When surgery is indicated, the choice of technique is performed intraoperatively according to the arthroscopic aspect of the residual ATFL. In our department, the technique used is either the arthroscopic Brostrom-Gould procedure repair if the ligament is thickened/disinserted or an anatomical reconstruction with autograft if ATFL is absent/thin. The purpose of this study was to assess the reliability and validity of preoperative MRI for surgical decision making in chronic lateral ankle instability.

      Methods

      This single-center prospective study included all patients who underwent an arthroscopic ankle stabilization between 2013 and 2016. The study complied with the recommendations of the group STARD. Preoperative MRI evaluation of ATFL was performed in axial T2-weighted images, twice, by 2 independent observers. Arthroscopy assessment, used as the gold standard, was carried out by a single senior surgeon. The primary endpoint was the ATFL aspect in two categories: (1)thin or absent/(2)avulsed or thickened. The intra and inter-observer agreement was assessed by the kappa coefficient (k). The diagnostic performance parameters of preoperative MRI were calculated.

      Results

      Twenty two patients were included in this study, 15 men/7 women, mean age 30.3±9.5 years. An anatomical ligament repair was performed in 14 patients (63.6%), and 8 patients (36.4%) underwent a ligamentoplasty with a gracilis autograft. The intra-observer reproducibility of MRI analysis was substantial (k=0.75 and 0.68) and inter-observer reproducibility was moderate (k=0.55) to almost perfect (k=0.87). In comparison with arthroscopy, the agreement was substantial and significant (k=0.70 and 0.80). Diagnostic performance parameters of preoperative MRI were good: sensitivity:85.7-87.5%, specificity:86.7-92.9%, and percentage of patients correctly classified 86.4-90.9%.

      Conclusion

      Preoperative MRI is a reliable and valid decision making tool for the choice of surgical stabilization technique in patients with chronic lateral ankle instability.