Accuracy of MRI scan in the diagnosis of ligamentous and chondral pathology in the ankle

Abstract

The aim of our study is to determine the accuracy of magnetic resonance imaging (MRI) scan in relation to arthroscopic findings in patients presenting with chronic ankle pain and/or instability. All patients who underwent arthroscopy of the ankle as well as MRI from December 2005 to July 2008 in our institution were reviewed by the Orthopaedic surgeons. Twenty-four patients were identified and the results of MRI scans were compared with arthroscopic findings. This study specifically looked at anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL) and osteochondral lesions (OCD). Arthroscopic findings were considered as a gold standard. There were 12 female and 12 male patients with an average age 39 years (11-65 years). Time interval between MRI scan and arthroscopy was 7.0 months (2-18 months). In our study MRI showed 100% specificity for the diagnosis of ATFL and CFL tears and osteochondral lesions. However sensitivity was low particularly for CFL tears. Accuracy of MRI in detecting ATFL tear was 91.7%, CFL tear was 87.5% and osteochondral lesion was 83.3%. We conclude that MRI scan has very high specificity and positive predictive value in diagnosing tears of ATFL, CFL and osteochondral lesions. However sensitivity was low with MRI. In a symptomatic patient negative results on MRI must be viewed with caution and an arthroscopy may still be required for a definitive diagnosis and treatment. However high resolution scans may differ in their ability to pick up these lesions and further research is required to assess their efficiency as evidence is not currently available.