The Diagnostic Role of Examination Under Anaesthesia and MRI in Chronic Symptomatic Lateral Ankle Ligament Instability.

Abstract

Chronic lateral ankle instability commonly develops following traumatic rupture or pathological laxity of the lateral ankle ligament complex. Although magnetic resonance imaging (MRI) is effective in identifying complete ligament tears, it may be less reliable in detecting functional ligament incompetence due to elongation or laxity. This study evaluates whether examination under anesthesia (EUA) provides superior diagnostic accuracy compared to MRI in patients with chronic lateral ankle instability. A prospective case analysis was performed on 49 symptomatic patients who underwent lateral ligament reconstruction. All patients underwent preoperative MRI and EUA. EUA was conducted under general anaesthesia using image-intensifier-guided anterior drawer and talar tilt stress tests. MRI scans were independently assessed by two experienced musculoskeletal radiologists. MRI findings were compared with both EUA and intraoperative findings. EUA demonstrated ankle instability in 48 out of 49 patients, with positive anterior drawer and talar tilt tests. When compared with intraoperative findings, MRI demonstrated a sensitivity of 59.2%. In comparison, the EUA showed a sensitivity of 98%. Intraoperative findings included complete ligament rupture in 17 patients (34.7%), ligament laxity in 18 (36.7%), elongated lateral ligament complex in 13 (26.5%), and partial rupture in 1 patient (2.0%). EUA, in conjunction with clinical symptoms, appears more reliable than MRI in diagnosing chronic lateral ankle instability and should be considered a key diagnostic tool in its management.