Anterior Ankle Impingement (AAI) results from soft tissue entrapment at the anterior margin of the tibiotalar joint during dorsiflexion. Magnetic Resonance Imaging (MRI) is often used to diagnose AAI, although the diagnostic accuracy has been debated. The purpose of this study is to determine the accuracy of MRI in the diagnosis of AAI, as compared to the diagnosis of other forms of impingement and bony pathology. It is hypothesized that MRI will not be an accurate tool for diagnosing AAI in patients.
Patients who underwent arthroscopy for ankle impingement performed by a board-certified orthopaedic surgeon were retrospectively evaluated. Forty-two patients were included in the study, with a total of 43 arthroscopic operations performed. All patients received a preoperative MRI, which was compared to intraoperative findings. MRI sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy were calculated for the presence of anterior impingement, lateral gutter impingement, posterior impingement, tibiofibular impingement, osteochondral defects, osteophytes, chondromalacia, and loose bodies.
MRI was found to be least accurate in detecting AAI at only 13.95% (sensitivity 11.9%, specificity 100%). All other forms of impingement had a <50% accuracy rate, with the exception of posterior ankle impingement, which had a 69.77% accuracy. The average accuracy rate for detecting ankle bony pathology (75.58%) was found to be much higher than the average accuracy rate for detecting soft tissue ankle impingement (34.89%).
The use of MRI for AAI is judged to be inadequate, as the accuracy was only 13.95%. These findings suggest that other diagnostic methods, such as physical examination and ultrasound, may be more cost-effective than MRI in diagnosing patients with suspected AAI.