Optimized anterior anatomical fusion plate for ankle arthrodesis: biomechanical and clinical outcomes

Ankle osteoarthritis (OA) is a common degenerative joint disorder that often necessitates ankle arthrodesis. Conventional fusion methods may offer limited fixation stability and require extensive soft-tissue exposure. The goal of this study was to evaluate the biomechanical properties of a geometrically optimized anterior anatomical fusion plate (AAFP) for ankle arthrodesis, which has been designed to enhance mechanical performance and minimize surgical trauma.

This study developed a finite element model of the ankle based on CT scans of a healthy male volunteer. Various fusion models were created, incorporating the optimized AAFP with or without transarticular screw, anterolateral fusion plate (ALFP) with or without transarticular screw, and configurations using three or two screws. The biomechanical performance of these systems was assessed by analyzing peak displacement of the fusion surface and peak von Mises stress of implants and bone-implant models under seven common ankle postures. Additionally, the preliminary feasibility of the optimized AAFP was assessed by analyzing the American Orthopaedic Foot & Ankle Society (AOFAS) scores and X-ray images.

The optimized AAFP with transarticular screw fixation exhibited great stability, with peak displacement of 0.14 mm in neutral position, 0.19 mm in dorsiflexion, 0.07 mm in plantar flexion, 0.09 mm in internal rotation, 0.07 mm in external rotation, 0.10 mm in inversion, and 0.12 mm in eversion. The peak stress of the fusion method was relatively low, with 132.91 MPa in neutral position, 145.83 MPa in dorsiflexion, 97.15 MPa in plantar flexion, 84.27 MPa in internal rotation, 74.70 MPa in external rotation, 98.07 MPa in inversion, and 88.00 MPa in eversion. The transarticular screw enhanced biomechanical stability of the optimized AAFP in ankle fusion by reducing stress and displacement. Clinically, the optimized AAFP showed satisfactory short-term outcomes, with improvements in the AOFAS scores (from 53 to 83, 57 to 82, 51 to 84 and 57 to 83) and imaging results.

These findings suggest that the geometrically optimized AAFP combines a smaller incision with favorable biomechanical performance and warrants further clinical evaluation as a potential option for ankle fusion.