Comparative strain‑gauge analysis of Gamma3 and Gamma3 reconstruction nails in unstable basicervical femur fractures: a pilot biomechanical study.

PURPOSE: Evidence supporting the mechanical superiority of the Gamma3 RC nail over the standard Gamma3 configuration remains limited. This pilot biomechanical study compared strain distribution and load-transfer behavior between both implants in a standardized unstable basicervical proximal femoral fracture model.

METHODS

Six fourth-generation composite femora were allocated into three groups: one intact reference specimen, three fractures stabilized with a standard Gamma3 nail, and three fractures stabilized with a Gamma3 RC nail incorporating a U-blade lag screw. Mechanical testing consisted of controlled low-load axial-oblique loading under standardized conditions. Four synchronized strain-gauge rosettes recorded cortical deformation at the proximal femur.

RESULTS

The Gamma3 RC construct demonstrated consistently lower strain magnitudes at the medial cortices and preserved a more linear strain-load response throughout the tested loading range compared with the standard Gamma3 configuration (Δε = 18.6 με and - 26.5 με). Differences between constructs became progressively more evident with increasing load (Δε = 180.9 με and - 62.9 με), particularly at the proximal medial cortex, where the standard Gamma3 showed greater strain concentration and early nonlinearity.

CONCLUSION

In this exploratory synthetic-femur model, the Gamma3 RC nail demonstrated a mechanical trend toward more homogeneous load distribution and improved rotational control compared with the standard Gamma3 nail.