The Anatomy And Biomechanics Research Of The Lateral Ankle Ligaments And The Intermalleolar Ligament

Objective:To designed to determine an describe precise anatomy of the lateral ankleligaments and the posterior intermalleolar ligament and their relationship toadjacent osseous structures,including their length,width and thickness.And tostudy the biomechanics of these ligaments.Materials and Methods:This study was performed on10ankle joints of adult human’s freshcadavers.The lateral ankle ligaments and the posterior intermalleolar ligamentwere carefully dissected.The precise location of origin,insertion points,coruseand the relationship to each others was observed.Mean values for thelength,width and angle of the individual lateral ankle ligament weremesaured.And the origins,insertion points,shaps and the anatomic variants ofthe posterior intermalleolar ligament were carefully dissected.Results:①In10cases,the anterior talofibular ligament of6cases is adouble-banded morphology,the rate of the anatomic variant is60%.②Accoreding to the measurment of the anterior talofibular ligament(unvariated),the of length,widty,thickness on average is25.82±2.67,7.12±2.45,1.72±0.40(mm).While the dimensions of the double-banded morphology is26.75±2.32,5.14±1.02,1.69±0.51(mm)(uper band);18.54±2.75,4.12±1.35,1.54±0.69(mm)(Inferior band).As this results,the totale dimensions of the width ofuper band and Inferior band is biger than the one has only one band,which isunvariated.③And in this morphology,the course of these two bands like a Chinese character "人"，the two bands have different characteristic.In plantarflexion, the inferior band of the ligament remains relaxed while the upper bandbecomes taut. In dorsiflexion, the upper band remains relaxed, and the inferiorband becomes tight.④The dimensions of the posterior talofibular ligament andcalcaneofibular ligament is23.97±2.45(21.25~26.42);4.54±0.89(3.65~5.43);3.01±0.57(2.44~3.58)，32.56±3.04(29.52~35.60)；4.67±1.52(3.15~6.19)；4.02±1.07(2.95~5.72)(mm).⑤In the posterior view, theposterior intermalleolar ligament is situated between the transverse ligamentand the posterior talofibular ligament and runs obliquely from lateral to medialand from downwards to upwards.The medial arising sites of the ligamentincluded the lateral border of the medial malleolar sulcus,the medial border ofthe medial malleolar sulcus through the septum between the flexor digitorumlongus and posterior tibial tendons, the posterior distal margin of the tibia,andthe posterior process of the talus through the joint capsule.⑥The posteriorintermalleolar ligament tenses during dorsiflexion and relaxes during plantarflexion, and therefore, trauma that causes forced dorsi-flexion of the ankle canbe assumed to produce either injury or rupture of this ligament, orosteochondral avulsion. Plantar flexion would cause it to relax and becomesusceptible to trapping between the tibia and the talus, leading toimpingement.Conclusions:Occording to this study,we have obtiande a describe precise anatomy ofthe double-band structure of the anterior talofibular ligament,and explored thedifferent biomechanics characters of the two bands.In addition, theorigins,insertion points,shaps and the anatomic variants of the posteriorintermalleolar ligament were carefully dissected.