SLR - June 2015 - Mina M. Hanna
Reference: Kim YS, Kim YB, Kim TG, Lee SW, Park SH, Lee HJ, Choi YJ, Koh YG. Reliability and Validity of Magnetic Resonance Imaging for the Evaluation of the Anterior Talofibular Ligament in Patients Undergoing Ankle Arthroscopy. Arthroscopy. 2015 April 14.Scientific Literature Review
Reviewed By: Mina M. Hanna, DPM
Residency Program: Morristown Memorial Hospital
Podiatric Relevance: As foot and ankle surgeons, we will encounter a great deal of chronic ankle instability as ankle sprains are one of the most common sports related injuries. The purpose of this study was to analyze the reliability and validity of magnetic resonance imaging (MRI) by comparing its results with arthroscopic findings for the detection of anterior talofibular ligament (ATFL) injuries in chronic lateral ankle instability.
Methods: This cohort study enrolled 79 patients who underwent MRI followed by subsequent ankle arthroscopy for their various ankle injuries. The magnetic resonance images were reviewed by 2 trained musculoskeletal radiologists who were blinded to the patient’s history and physical examination. An ATFL injury was diagnosed on MRI if any one of the following criteria was present: “nonvisualization of the ligament, discontinuity, a wavy or curved contour, or increased signal intensity within the ligament.” Arthroscopic evaluation was performed by a single surgeon and the assessment was used as the standard of reference. An ATFL injury was diagnosed with arthroscopy if any one of the following criteria was present: “an abnormal course of the ligament, a decrease in the tautness of the ligament, discontinuity of the ligament with or without the defect being filled by fibrous tissue, and an avulsion at the attachment to the fibular or talus”. Moreover, the location of the ATFL injury was based on the following criteria: “fibular attachment site, midsubstance site, talar attachment site, or multiple sites.” The interclass correlation coefficient (ICC) and confidence interval (CI) were used to assess interobserver reliability.
Results: The total number of ATFL injuries identified by arthroscopy was 55. The interobserver reliability of detecting ATFL injuries with MRI was excellent with an ICC of 0.915. The MRI sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for reader A were 83.6 percent, 91.7 percent, 71 percent, 95.8 percent, and 86.1 percent and for reader B were 76.4 percent, 83.3 percent, 60.6 percent, 91.3 percent, and 78.5 percent, respectively. The MRI sensitivity for identifying ATFL injuries based on location at the fibular attachment site and talar attachment sites were 72.7 percent and 80.0 percent for reader A and 63.6 percentand 66.7 percent for reader B, respectively. The MRI sensitivity was 100 percent for readers A and B at the midsubstance and multiple sites. All cases of false negative diagnoses were observed at the talar or fibular attachment site.
Conclusions: MRI is a useful diagnostic method for detecting ATFL injuries in patients with chronic lateral ankle instability. In the diagnosis of ATFL injuries, the MRI specificity and positive predictive value were very high while the sensitivity and negative predicative value were relatively low. When evaluating patients with lateral ankle instability, modalities such as MRI and arthroscopy can be valuable tools in diagnosing various ankle disorders.