Finite element analysis of nonanatomic tenodesis reconstruction methods of combined anterior talofibular ligament and calcaneofibular ligament deficiency.

Background: Nonanatomic tenodesis reconstruction procedures have been used for lateral ankle ligament reconstruction. However, there has been no comparison of Watson-Jones, Evans, and Chrisman-Snook procedures with respect to biomechanical characteristics such as kinematics, ligaments and grafts stresses using finite element analysis.

Methods: A three-dimensional finite element model of the ankle including seven bony structures, cartilage and nine principal ligaments surrounding the ankle joint complex was developed and validated. In addition to the intact model, combined anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) deficient, Watson-Jones reconstruction, Evans reconstruction and Chrisman-Snook reconstruction models were simulated. Then, the forces in the ligaments and grafts and the kinematics of the talus and calcaneus were predicted for an inversion or internal torque of 1.7 Nom and an anterior drawer stress of 150 N through the range of ankle motion.

Results: All three operations were able to improve the stability of the ankle, but the effectiveness of each procedure was dependent on the direction of the stress applied and the position of the ankle in dorsiflexion-plantarflexion.

Conclusion: This study showed that the Watson-Jones procedure has advantages with regard to anterior and rotational stabilities as well as ligaments and grafts stresses in comparison with other nonanatomic tenodesis reconstruction methods.

Clinical Relevance: The knowledge of stress inside the ligaments and reconstructed grafts could help to better understand the biomechanical behavior of the reconstructed joint.