ABSTRACT
[Objective]To observe the changes of contact characteristics of the subtalar joint after calcaneus fracture in load condition, so as to provid a theoretical basis for its clinical treatment.[Method]Six fresh speciments consisting of foots and lower legs were harvested.A specimen,including an intact foot and 15~20cm of the distal tibia and fibula prepared by removing the skin,muscle and tendons down to the level of the hindfoot and the ligaments and joint capsules were kept intact with the exception of the posterior aspect of the posterior facet and the lateralaspect of middle and anterior facets of the talocalcaneal joint.The pressure sensitive film was inserted into the posterior and anterior-middle facets of the talocalcaneal articulation,and 500-N load was applied in the neutral position.After testing of the intact foot,the calcaneus was splited into anterointernal and posterolateral compoments using microoscillating saw to simulate primary fracture of calcaneus.The test was repeated after tile posterolateral fragment was anatomically reduced and displaced 2mm,5mm and 10mm respectively in a planter direction.The changes of contact characteristics of the subtalar joint ware recorded.[Result]The average pressure area of the intact posterior facet was(275.67?46.02) mm~2,the average stress to bear the weight was(1.83?0.56) MPa.The bearing average pressure area decreased to(167.67?25.09) mm~2 when the posterolateral compoment was displaced to plantar in 2 mm,it was significantly lower(P0.05).The bearing stress the anterior and middle facets significant increased only in a 1 10mm plantar displacement of the posterolateral component(P