Relative contribution of the nail and plate to a nail‐plate construct for comminuted distal femoral fractures

Abstract

The purpose of this study was to assess the biomechanical contributions of the nail and the plate individually to a complete nail‐plate construct in the setting of comminuted distal femur fractures. For this biomechanical study, comminuted extra‐articular distal femur fractures were created in 24 synthetic osteoporotic femur models. These were then split into three groups: the nail‐only group, the plate‐only group, and the nail‐plate group. After fixation, each specimen underwent sequential axial and torsional loading, and axial and torsional stiffness were calculated and compared. The addition of a nail to a plate‐only construct increased axial stiffness by 19.7% and torsional stiffness by 59.4%. The plate‐only group and nail‐plate group both demonstrated significantly greater axial and torsional stiffness than the nail‐only group at all levels of axial and torsional load. (p < 0.001) At 1000 and 2000 N of cyclic loading, the nail‐plate group demonstrated significantly greater axial stiffness than the plate‐only group (p ≤ 0.018). The nail‐plate group demonstrated greater torsional stiffness than the plate‐only groups at all levels of torsional loading (p < 0.001). In osteoporotic comminuted distal femur fracture models, most of the axial stiffness in a nail‐plate construct comes from the plate. While the combination of the two constructs is not fully additive, the plate contributes the majority of the axial and torsional stiffness in a nail‐plate construct. The supplementation of the plate with a nail primarily helps to increase resistance to rotational forces. Level of Evidence: III.