The mechanical effect of the common fibers of the anterior talofibular and calcaneofibular ligaments

OBJECTIVES: The subject of the lateral ankle ligament complex is a familiar one. Common fibers between the inferior bundle of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) have been described. The purpose of this study is to investigate the possibility of transmitting a force to the CFL through the inf. ATFL. METHODS: An anatomical study was carried out on 12 ankles. Each specimen was dissected according to a protocol to expose the lateral ligaments. A proximal section was made in the superior and inferior bands of the anterior talofibular ligament. A device capable of measuring shifting from one point in relation to another fixed point was used. The fixed point was implanted on the calcaneus and the other part of the sensor on the CFL. Traction of 1-kilogram was applied to the inferior band of the ATFL while the device measured the shifting of the CFL in millimeters. Two measurements were taken on each specimen by two observers. Sample data and distance measurements were recorded and analyzed. RESULTS: It was possible to analyze 12 specimens. The specimens were from 7 women and 5 men and included 6 right and 6 left ankles. The anterior talofibular ligament was identified as a two-band ligament in all cases. One ankle had a lesion on the superior band of the ATFL. Common fibers that connect the inferior ATFL and the CFL were observed in all samples of this study. The measuring device showed shifting of the CFL in each case. The first series of measurements indicated average shifting of 0.74 mm (0.46; 1.35; +/- 0.34) and a median of 0.59 mm. The second series indicated a mean of 0.60 mm (0.23 - 1.13; +/- 0.32) and a median of 0.46 mm. CONCLUSION: There is an anatomical connection between the inferior ATFL and the CFL that is capable of transmitting a mechanical force to the CFL when the inferior ATFL is placed in traction. Improvement in the knowledge of the mechanical properties of the lateral ligament plane helps to clarify the possibilities for surgical repairs.