Reliability and validity of preoperative MRI for surgical decision making in chronic lateral ankle instability

To evaluate the value of analyzing the anterior talofibular ligament (ATFL) on preoperative MRI as a decision-making tool to determine the surgical technique in patients undergoing surgery for chronic lateral ankle instability.

A retrospective study of prospective data was performed. All patients who underwent surgery between 2013 and 2016 for arthroscopic stabilization of the ankle were included. The ATFL was evaluated on preoperative MRI including axial T2-weighted images by two readers who were blinded to arthroscopic results. The arthroscopic evaluation, which was considered to be the reference examination, was performed by one senior surgeon. The main judgment criteria were two features of the ATFL: (1) absent or thin (< 1 mm thick) and (2) detached or thickened (> 3.2 mm in diameter) with or without a high intensity intraligamentous signal. Inter- and intraobserver reproducibility was evaluated by the kappa coefficient (k), and parameters of the diagnostic accuracy of preoperative MRI were analyzed.

Twenty-two patients were included, 15 men/7 women mean age 30.3 ± 9.5 years. Fourteen patients (63.6%) underwent arthroscopic repair of the ATFL (Broström-Gould technique) and 8 patients (36.4%) an arthroscopic anatomical reconstruction of the ATFL. Intraobserver reproducibility of MRI findings was substantial (k = 0.68) and interobserver reproducibility moderate (k = 0.55) to nearly perfect (k = 0.87). Agreement between MRI and arthroscopic findings was substantial (k = 0.70). Diagnostic parameters of preoperative MRI were good for both observers: Se = 85.7-87.5%, Sp = 86.7-92.9%, PPV = 75-87.5%, NPV = 92.9%, and classification of patients was good = 86.4-90.9%.

Preoperative MRI of the ATFL is a reliable and valid decisional tool to choose the surgical technique for stabilization of chronic lateral ankle instability.

Level II; Diagnostic study-development of diagnostic criteria on the basis of consecutive patients.