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Anatomy of the Anterior Talofibular Ligament Bader Khawaji and Roger Soames Centre for Anatomy and Human Identification, College of Life Sciences, University of Dundee, UK Results & Discussion 2. Introduction Of the lateral collateral ligaments the anterior talofibular ligament (ATFL) is the most frequently injured (van den Bekerom et al., 2008), being seen in approximately two thirds of ankle sprains (Kumai et al., 2002). The morphology of the ATFL has been investigated previously (Burks & Morgan, 1994, Milner & Soames, 1997), however there is disagreement about the number of the ATFL bands (Golano et al., 2010). In addition, the ATFL bands were not studied separately under different positions of the ankle joint. Aims The aims of this study were: (1) study the anatomy and morphology of the ATFL (attachments, orientation, length, width and thickness); and (2) investigate the anatomical variations of the ATFL. Three Bands, 12.9% The superior band of the ATFL is the largest band widest band and it is considered as the main component of the ATFL. It has been suggested that the inferior and middle bands are the additional bands. One Band, 25.8% The length of the superior band is maximum during plantarflexion and minimum during dorsiflexion (Figure 5). Two Bands, 61.3% The inferior band becomes taut during plantarflexion and lax in the neutral position of the ankle joint. Figure 1: Number of the ATFL bands Materials and Methods The middle band is the smallest band of the ATFL: it is lax during dorsiflexion becoming tense during plantarflexion. Figure 4: Three band form of the ATFL Band and Position Range (mm) Mean (mm) Standard Deviation Superior (Neutral) Superior (Dorsiflexion) Superior (Plantarflexion) Inferior (Neutral) Inferior (Dorsiflexion) Inferior (Plantarflexion) Middle (Neutral) Middle (Dorsiflexion) Middle (Plantarflexion) 13.85 – 31.94 13.97 – 30.78 15.58 – 34.88 13.63 – 23.4 12.17 – 21.24 14.78 – 23.2 10.77 – 21.26 11.51 – 23.37 16.08 – 22.9 21.27 20.24 21.96 17.75 17.83 18.69 15.97 16.96 19.82 3.55 3.67 4.02 2.75 2.56 2.36 4.37 5 3.24 Conclusion Table 1: The length of the ATFL bands under different conditions Thirty four feet were dissected from 17 European Caucasian formaldehyde embalmed cadavers (11 female, 6 male; aged 68 to 98 years). The skin, fascia, muscles and tendons on the posterior and lateral aspects of the ankle were removed and the ATFL exposed. The number of the bands of the ATFL, their attachments , orientation and thickness were assessed and measured and photographs taken. Each band length was measured using a digital calliper with the ankle positioned in neutral, dorsiflexion and plantarflexion. The width of each ATFL band was measured at three points: the middle and the proximal and distal attachments. ATFL Band Level Range (mm) Mean (mm) Standar d Deviati on Superior band width Proximal Middle Distal Proximal Middle Distal Proximal Middle Distal 2.38 – 8.01 1.52 – 8.89 1.07 – 7.08 2.33 – 7.6 2.21 – 6.97 1.14 – 6.85 1.76 – 2.71 1.22 – 2.82 1.46 – 2.87 0.36 – 2 0.37 – 1.98 0.49 – 1.69 4.88 4.71 3.98 4.33 4.23 3.29 2.04 2.1 1.99 1.25 0.89 0.93 1.41 1.46 1.02 1.35 1.2 1.2 0.45 0.66 0.61 0.48 0.4 0.55 Inferior band width Middle band width Figure 2: One band form of ATFL Results & Discussion 1 Superior band thickness Inferior band thickness Middle band thickness Table 2: Width and thickness of ATFL bands The ATFL originates from the anterior border of the lateral malleolus and runs anteromedially to attach to the talus. The ligament is directed proximally during dorsiflexion and distally during plantarflexion. One, two and three band forms of the ATFL were observed (Figure 1). An understanding of the anatomy and variations of the anterior talofibular ligament will help in diagnosing and treating ATFL injury, usually caused by ankle sprains. A sound knowledge of ATFL variations is necessary to be able to read MRI images in diagnosing injuries. This study has highlighted the anatomical variation of the ATFL, with some findings being inconsistent with previous studies. The bands of the ATFL were investigated separately under different conditions (plantarflexion, neutral, dorsiflexion), which will aid in the understanding ATFL function. The results are encouraging: further investigation swill be conducted. Reference: Burks, R. T. & Morgan, J. 1994. Anatomy of the lateral ankle ligaments. The American journal of sports medicine, 22, 72-7. Golano, P., Vega, J., De Leeuw, P. A., Malagelada, F., Manzanares, M. C., Gotzens, V. & Van Dijk, C. N. 2010. Anatomy of the ankle ligaments: a pictorial essay. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 18, 557-69. Kumai, T., Takakura, Y., Rufai, A., Milz, S. & Benjamin, M. 2002. The functional anatomy of the human anterior talofibular ligament in relation to ankle sprains. Journal of anatomy, 200, 457-65. Milner, C. E. & Soames, R. W. 1997. Anatomical variations of the anterior talofibular ligament of the human ankle joint. Journal of anatomy, 191 ( Pt 3), 457-8. Van Den Bekerom, M. P., Oostra, R. J., Alvarez, P. G. & Van Dijk, C. N. 2008. The anatomy in relation to injury of the lateral collateral ligaments of the ankle: a current concepts review. Clinical anatomy, 21, 619-26. The one band form was seen in 25.8% of specimens (Figure 2), with approximately two third being observed in the left foot : all except one were unilateral. The two band form (Figure 3) was observed in 61.3% of specimens, with approximately two third being observed in the right foot: 47.4% were bilateral. 12.9% of the specimens were observed to have three bands (Figure 4); 75% were associated with the right foot and were present unilaterally. The lengths, widths and thicknesses of the different bands of the ATFL in all ankle positions are shown in Tables 1 and 2 respectively. The width of all bands at the proximal attachment was larger than at the distal attachment. The results of this study suggest that the bands of the anterior talofibular ligament have important roles in limiting ankle movement, particularly plantarflexion. Figure 3: Two band form of the ATFL Figure 5: Length of the ATFL bands under different conditions