Research of movement of plantarflexion and dorsiflexion of the ankle

Objective:To provide medical image evidence to the function evaluation of ankle,the diagnosis of the lower tibiofibular symphysis separation and ankle front-back dislocation in the treatment of Pilon fracture.Methods:The frontal and lateral X-ray image of ankle in 35 adults were obtained including 21 males(42 ankle),14 females(28 ankle) age from 21 to 48 years(mean 31.6 years).The maximal angle of initiative movement of plantarflexion and dorsiflexion of ankle and the width of peripheral tibiofibular joint,the width of the overlap image of lateral tibia and fibula,and the distance between geometrical center of the articular surface of talus-ankle and middle axes of shank were measured.Results: No statistical significance was found in ankle dorsiflexion(male 27.6°±5.2°;female 26.5° ±6.1°) and plantarflexion(male 40.8°±3.1°;female 43.9°±4.8°) between male and female.Width of peripheral tibiofibular joint beyond 3.5 mm and the overlap of distal tibia and fibula less than 5.5 mm were indicated joint separation.The width of peripheral tibiofibular joint varied little in ankle neutral and dorsiflexion position but lessened by 2 mm were indicated anterior-posterior ankle dislocation.The distance of geometrical center:maximum of ankle dorsiflexion was 2.4 mm and plantarflexion was 2.5 mm in male,ankle dorsiflexion maximum was 1.9 mm and plantarflexion 2.0 mm in female;The minimum of them was all 0 mm.Conclusion:No obvious difference exist(P0.05) between male and female,either in dorsiflexion or in plantarflexion,there is no gender difference in the flexibility of the ankle movement.The maximal angle of initiative movement of plantarflexion and dorsiflexion of ankle offers a reference to the assessment to the function of ankle in the Pilon fracture.When the width of lower tibiofibular symphysis is more than 3.5 mm,it is considered as lower tibiofibular symphysis separation.When the width of the overlap image of lateral tibia and fibula is less than 5.5 mm,there is possibility that lower tibiofibular symphysis separation would happen,the distance which is more than 2 mm between geometrical center of the joint surface of talus-ankle and middle axes of shank gives a clue to front-back dislocation of anklebone.It is of big significance for the lateral stability and front-back stability of the ankle recovery to notice the two indexes at the same time within the anatomy location recovery of Pilon fracture,and it can as well instruct the treatment and recovery of anklebone fracture.