Introduction 5 25 14 33 32 20 18 8 32 4 6 8 9 12 16 19 28 29 34 34 3 21 9 11 17 4 21 4 1 2 4 8 12 22 The objective of this article was to review the literature concerning the anatomy, pathogenesis, symptoms and treatment of the AITFL impingement and finally to formulate treatment recommendations. Anatomy of the anterior inferior tibiofibular ligament 7 10 15 24 26 24 7 22 4 22 4 22 22 15 23 22 22 24 22 22 1 21 26 21 22 4 15 26 Fig. 1 The distal fascicle in relation to the anterior inferior tibiofibular ligament  24 1 24 Table 1 24  Maximum Minimum Mean Ligament length (cm) 3.4 2.1 2.6 ± 0.3 Ligament width (cm) 1.3 0.2 0.4 ± 0.2 Gap (cm) 0.5 0.1 0.2 ± 0.1 Declination angle (deg) 155.0 121.5 136.3 ± 7.4 2 4 22 24 24 26 11 24 24 2 Table 2 24 Type 1 Multiple fascicles (more than three) with or without small gaps between adjacent fascicles   1A The inferior fascicle is separated from the rest of the ligament by a gap and possesses its own distinct proximal and distal attachments   1B The inferior fascicle is not completely separated from the rest of the ligament by a gap. Either its proximal or its distal attachment is continuous with the rest of the ligament   1C Multiple fascicles without gaps intervening between them Type 2 Three fascicles or less. A distinct inferior fascicle with both its proximal and distal attachments separate from the rest of the ligament. The inferior fascicle is separated completely from the main portion of the ligament by a gap Type 3 Three fascicles or less. A distinct inferior fascicle with either its proximal or its distal attachment continuous with the rest of the ligament. A gap does not completely separate the inferior fascicle from the rest of the ligament Type 4 Three fascicles or less. The lower portion of the ligament possesses an inferior fascicle with both its proximal and distal attachments for the rest of the ligament Type 5 Three fascicles or less. A ligament with no separations or gaps within its structure. It may or may not possess a fascicular arrangement Pathomechanism of the impingement syndrome It should be stressed that most studies were carried out in vitro and do not take muscular tonus and the effects of weightbearing into consideration, we performed a review of the pathomechanism of the impingement syndrome caused by the distal fascicle of the AITFL. 4 4 4 2 2 2 4 13 2 4 22 22 2 24 1 1 22 22 24 2 4 4 On base of these studies we conclude that anterolateral hyperlaxity results in anterior extrusion of the talar dome with dorsiflexion, which contacts the inferior fascicle of the AITFL with more pressure and friction. This hyperlaxity was most likely due to an injured ATFL. Wider and longer fascicles and a fibular insertion point far from the joint level have more potential to become pathological. Often contact between the AITFL and the superolateral corner of the talus and an abraded region of the cartilage of the talus can be observed during arthroscopy. Diagnosis 4 2 4 4 2 1 1 4 Treatment 5 1 1 1 4 30 31 9 19 28 2 2 24 2 22 Fig. 2 There is contact between the distal fascicle of AITFL and the talus in dorsiflexion with bending of this fascicle  1 4 12 1 4 12 The decision to perform an arthroscopy of the ankle is typically based on the patient’s history and physical examination. When an impinging distal fascicle of the AITFL and an abraded anterolateral region of the talus were observed during an ankle arthroscopy, the surgeon should look for the criteria described above to decide whether it is pathological and needs to be resected. Conclusion Because of the lack of evidence only preliminary conclusions can be drawn. The AITFL started from the distal tibia, 5 mm in average above the articular surface, and descended obliquely between the adjacent margins of the tibia and fibula, anterior to the syndesmosis to the anterior aspect of the lateral malleolus. The incidence of the accessory fascicle differs very widely in the several studies. The presence of the distal fascicle of the AITFL and also the contact with the anterolateral talus is probably a normal finding. It may become pathological, however, due to anatomical variations and/or anterolateral instability of the ankle resulting from an ATFL injury. When observed during an ankle arthroscopy, the surgeon should look for the criteria described to decide whether it is pathological and considering resection of the distal fascicle.