A biomechanical analysis of two anterior ankle arthrodesis systems

An increasingly popular ankle fusion method uses plates and screws positioned on the anterior aspect of the tibiotalar joint. This study compared the mechanical properties of 2 contemporary plate systems for ankle arthrodesis, one based on a single anterior plate and the other comprising paired anteromedial and anterolateral plates.

Ten matched pairs of fresh-frozen cadaver ankle joints underwent arthrodesis with a single anatomically contoured anterior plate or 2 anatomic plates applied anteromedially and anterolaterally. Each arthrodesed specimen was subjected to controlled sagittal and coronal plane bending and internal and external rotation. Tibiotalar joint bending stiffness, bending angulation, torsional stiffness, and joint rotation were documented.

Bending stiffness of the 2-plate system was 1.5 to 5 times greater than that of the single-plate system in plantarflexion, dorsiflexion, eversion, and inversion (P = .005-.050). Angulation in each bending direction was several-fold greater than for the single plate (P = .005-.014) at the peak applied moment. Torsional stiffness of the 2-plate system nearly doubled that of the single plate in both rotation directions (P = .014, P = .005). Approximately half as much arthrodesis site rotation occurred with 2-plate fixation at the peak applied torque (P = .005, P = .007).

The tested 2-plate arthrodesis system has the potential to optimize arthrodesis site stiffness compared with fixation with a contemporary single plate.

Use of the stiffer 2-plate system could improve the clinical fusion rate, especially in patients with suboptimal bone quality.