MAGNETIC RESONANCE IMAGING IN A SPECIALIST FOOT AND ANKLE PRACTICE: ASSESSING ACCURACY AS COMPARED WITH ARTHROSCOPIC FINDINGS IN THE DIAGNOSIS OF ANKLE PATHOLOGY

Abstract

Ankle intra-articular pathology after acute injury is common and often under-diagnosed. While the majority of soft tissue injuries improve with rehabilitation, up to 40% of patients experience chronic pain, stiffness or instability. MRI is increasingly used in the investigation of such patients; however interpretation of MRI findings requires specialist expertise. The aim of this study was to determine the diagnostic potential of magnetic resonance imaging (MRI) compared to ankle arthroscopy.

Forty consecutive patients presenting with ankle pain of at least three months duration were included in the study. This cohort of patients underwent magnetic resonance imaging (MRI) and then arthroscopy.

Pre-operative MRI reported findings were compared with the arthroscopic findings. The sensitivity, specificity, positive and negative predictive value of MRI for diagnosing ankle pathology was then assessed. The 2 senior authors reviewed the MRI scans and their findings correlated.

The average time between injury and presentation to our service was 2.2 years. This interval ranged from 3 months to 10 years. 51% of patients gave history of inversion and/or plantar flexion injuries. 14 % had symptoms, which persisted following an ankle fracture. At arthroscopic evaluation 23 patients had osteochondral defects and 37 had evidence of synovitis. MRI identified 50% of the osteochondral defects with sensitivity 50% and specificity 100%. Synovitis was not identified in any of the patients on preoperative MRI but 33% of the preoperative MRI did demonstrate a joint effusion.

Despite the high rate of discordance between MR imaging and arthroscopy in our study MRI still remains a useful adjunct in the investigation of ankle pain. The implications for practice and further study are discussed.