Efficacy of MRI Versus Arthroscopy for Evaluation of Sinus Tarsi Syndrome

Background: Magnetic resonance imaging (MRI) has been used to diagnose sinus tarsi syndrome (STS) because of its non-invasiveness and accuracy. The purpose of the present study was to evaluate the diagnostic efficiency of MRI compared with subtalar arthroscopy for STS. Materials and Methods: Twenty-eight patients (30 feet) who had undergone both MRI and subtalar arthroscopy for STS were evaluated. MRI results were compared with arthroscopic findings, which were considered the standard. Sensitivity, specificity, and positive and negative predictive values were calculated, and correlations between MRI and arthroscopic findings were investigated. Results: MRI was found to detect interosseous talocalcaneal ligament (ITCL) tears, cervical ligament (CL) tears, sinus tarsi fat alterations, and synovial thickening, with sensitivities, specificities, positive and negative predictive accuracies of: 44%, 60%, 85%, 18% (ITCL tears); 73%, 89%, 80%, 86% (CL tears); 71%, 92%, 93%, 71% (sinus tarsi fat alterations); and 86%, 87%, 67%, 95% (synovial thickening). Correlations between MRI and arthroscopic findings showed full agreement in 10%, partial agreement in 50%, and no agreement in 40%. Conclusion: MRI is useful for detecting CL tears, sinus tarsi fat alterations, and synovial thickening, but is inadequate for correctly detecting ITCL tears.