Characteristics and Outcomes of Surgical Treatment for Anterolateral Ankle Impingement Due to the Distal Fascicle of the Anterior Inferior Tibiofibular Ligament.

Background: The pathomechanism of anterolateral ankle impingement (ALAI) due to the distal fascicle of the anterior inferior tibiofibular ligament (DF-AITFL) has not been fully elucidated. In addition, because of its rarity, no definitive diagnostic criteria have been established for ALAI due to DF-AITFL.

Purpose: To document the symptom characteristics and magnetic resonance imaging (MRI) and and arthroscopic findings as well as postoperative clinical outcomes of ALAI due to DF-AITFL.

Study Design: Case series; Level of evidence, 4.

Methods: Included were 12 patients (5 male and 7 female; mean age, 34.4 years [range, 21-76 years]) who were diagnosed with ALAI due to DF-AITFL and underwent excision of the DF-AITFL from November 2017 to August 2021. Symptom characteristics and symptom-related medical histories were evaluated, as were MRI and arthroscopic findings. Clinical outcomes were assessed using the visual analog scale for pain, American Orthopaedic Foot & Ankle Society ankle-hindfoot functional scale, and Foot Function Index.

Results: All 12 patients had a history of ankle sprain before symptom onset. DF-AITFL was confirmed by MRI in all patients. Bone edema of the talus was observed in 2 patients (16.7%), and cartilage abnormalities in 3 patients (25%). Arthroscopy showed that the DF-AITFL contacted the anterolateral aspect of the talar dome during range of motion in all patients and that the AITFL was bent where it contacted the anterolateral dome of the talus in 3 patients (25%). Partial tear or adhesion of the DF-AITFL was noted in 7 patients (58.3%), and cartilage deformation at the anterolateral talar dome in 4 patients (33.3%). Mean visual analog scale pain, American Orthopaedic Foot & Ankle Society, and Foot Function Index scores improved significantly from preoperatively to postoperatively.

Conclusion: ALAI due to DF-AITFL should be considered a possible cause of anterolateral ankle pain after an ankle sprain. The diagnosis can be reliably made with a thorough clinical examination and imaging studies. Half of the patients in this series also had lateral ankle instability. Surgical resection of the DF-AITFL and ligament reconstruction, if necessary, resulted in significant symptom improvement.