Biomechanical comparison of the femoral neck system and the dynamic hip screw in basicervical femoral neck fractures

Abstract

The purpose of this study was to compare the fixation stability of proximal fragments and the mechanical characteristics in proximal femur models of basicervical femoral neck fracture fixed by the femoral neck system (FNS) versus the dynamic hip screw. The mean axial stiffness was 234 +/- 35 N/mm in the FNS group and 253 +/- 42 N/mm in the DHS group, showing no significant difference (p = 0.654). Mean values for x-axis rotation, y-axis rotation, and z-axis rotation after cycle load were 2.2 +/- 0.5 degrees, 6.5 +/- 1.5 degrees, and 2.5 +/- 0.6 degrees, respectively, in the FNS group and 2.5 +/- 0.7 degrees, 5.8 +/- 2.1 degrees, and 2.2 +/- 0.9 degrees, respectively, in the DHS group, showing no significant differences (p = 0.324, p = 0.245, and p = 0.312, respectively). The mean values of cranial and axial migration of screws within the femoral head were 1.5 +/- 0.3 and 2.1 +/- 0.2 mm, respectively, in the FNS group and 1.2 +/- 0.3 and 2.4 +/- 0.3 mm, respectively, in the DHS group, showing no significant differences (p = 0.425 and p = 0.625, respectively). The average failure load at vertical load was 1342 +/- 201 N in the FNS group and 1450 +/- 196 N in the DHS group, showing no significant difference (p = 0.452). FNS fixation might provide biomechanical stability comparable to that of DHS for treating displaced basicervical femoral neck fractures in young adults.