Three-dimensional Finite Element Analysis Of Ankle Arthrodesis With Intramedullary Nail And Locking Plate

Objective To evaluate the effect of two internal fixations(GSH and LPHP)for ankle arthrodesis by using the three-dimensional finite element method,and compare their advantages and disadvantages to offer reasonable recommendations for the clinical selection of internal fixations.Methods A three-dimensional model of normal ankle was developed from computed tomography images.The model of ankle arthrodesis was built by finite element analysis software to simulate mechanical analysis of ankle under four activity patterns of ankle(neutral position,dorsiflexion,external rotation and internal rotation).Results1.The displacement of tibia and talus all have the phenomenon of concentration distribution,the position of which is almost the same.The maximum displacement of tibia and talus in LPHP is less than that in GSH.The contact surface displacement distribution have the same feature.The interface maximum displacement of LPHP and GSH were 156.37 μm,201.72 μm,more than 150 μm respectively,under the load of 10 Nm in external rotation;2.The stress distribution of tibia and talus all have the phenomenon of concentration,the site of which is almost the same.The maximum stress of tibia and talus in LPHP is greater than that in GSH.The contact surface stress distribution have the same characteristic;3.The stress distribution of internal fixation all have the phenomenon of concentration,the location of which is almost the same.The maximum stress of the internal fixation in LPHP is greater than that in GSH.Conclusions1.In terms of biomechanics,LPHP is better;2.After the operation,proper external fixation should be taken to limit the external rotation of the ankle.