Pseudoband formation: Missed ATFL tears on MR imaging

Background: The anterior talofibular ligament (ATFL) is the ligament most commonly injured during ankle sprains. Objective: The purpose of this investigation was to assess the sensitivity of Magnetic Resonance (MR) imaging for ATFL with open surgery, Brostrom-Gould surgical interventional considered the gold standard. Methods: A retrospective chart review using Operating Room (OR) and MR reports from April 2008-November 2009 led to a review of 137 charts, with 15 cases meeting the inclusion criteria. Results: The sensitivity for ATFL tears irrespective of extent of the tear was 93%. For full thickness ATFL tears, 10 were found to be positive on MR but 13 on OR with a sensitivity of 77%. Of the three missed cases, 2 were described as sprain injuries and the other normal using MRI. Conclusion: The recommendations for MR assessment of ankle injury include use of dedicated sequences and understanding the “pseudoband” concept. The two full thickness and two partial thickness tears on OR described as sprain injuries on MRI had a band of inflammatory granulation tissue. This tissue accounted for the appearance of the thick continuous band at MRI, the pseudoband. This study reaffirms the usefulness of MR in determining ATFL tears, aiding surgical decision making.