Comparison of the effect of osteotomy type, screw type, and configuration on stability in medial malleolus osteotomy: Biomechanical analysis.

BACKGROUND

Access to the medial dome of the talus may sometimes require medial malleolus osteotomy (MMO) in ankle surgeries.

PURPOSE: This study compared the biomechanical stability of cortical screws and headless compression screws used in double and triple screw configurations with oblique and chevron MMO.

STUDY

DESIGN

This study was conducted using 64 artificial distal tibial bone models (Selbones®, Kayseri, Turkey) for simulated MMO. The models were randomly divided into eight groups based on osteotomy techniques, screw types, and fixation configurations.

METHODS

For each model, axial load values (newtons [N]) required to achieve 3 mm and 5 mm displacement, stiffness (N/mm), and photographic joint step formation (mm) were measured.

RESULTS

Axial load values varied significantly among the groups at both displacement levels (p < 0.05). The oblique MMO group fixed with two compression screws showed the lowest stiffness, while the chevron MMO group fixed with three cortical screws exhibited the highest stiffness. No significant differences were found among the groups regarding joint step formation at a 5 mm displacement. Furthermore, triple screw configurations demonstrated a significantly higher load-bearing capacity and stiffness compared to double screw configurations, regardless of the screw type or MMO technique used (p < 0.05).

CONCLUSIONS

The oblique and chevron MMO techniques, along with fixation methods using cortical and headless compression screws, exhibited similar biomechanical performance. However, triple screw fixation offers superior biomechanical stability compared to double screw constructs. Among the methods tested, the chevron MMO fixed with three cortical screws demonstrated the most favorable biomechanical properties.