Biomechanical comparison of tenodesis reconstruction for subtalar instability: a finite element analysis

Background: There are several types of tenodesis reconstruction designed for subtalar instability. However, no comprehensive comparison has been conducted among these procedures in terms of their correcting power so far. The objective of this study is to evaluate the biomechanical behaviors of 5 representative procedures through finite element analysis. Methods: : A finite element model was established and validated based on one of our previous studies. The Pisani interosseous talocalcaneal ligament(ITCL) reconstruction, Schon cervical ligament(CL) reconstruction and Choisne calcaneofibular ligament(CFL)reconstruction were compared on a model with the CFL, ITCL and CL sectioned. The Schon triligamentous reconstruction and Mann triligamentous reconstruction were compared on a model with the CFL, ITCL and CL, as well as the anterior talofibular ligament (ATFL) sectioned. The inversion and external/internal rotation were quantified in different ankle positions with rotational moment. Results: For single ligament reconstruction, the Choisne CFL reconstruction provided the greatest degree of correction for subtalar instability, followed by the Schon CL reconstruction and then the Pisani ITCL reconstruction. For triligamentous reconstruction, the Mann procedure outperformed the Schon procedure in alleviating the subtalar instability. Conclusion: The finite element analysis showed that the Choisne CFL reconstruction and Mann triligamentous reconstruction provided the greatest degree of immediate postoperative subtalar stability. However, both procedures could not restore the biomechanical behaviors of the subtalar joint to normal. The long-term efficacy of these procedures warrants further investigation using a substantially larger sample of clinical cases.