Biomechanical comparison of prophylactic fixation methods following excision of benign aggressive tumors of the femoral neck using composite bone models.

BACKGROUND: The optimal fixation strategy for femoral neck defects following curettage of locally aggressive benign bone tumors remains unclear. This study aimed to compare the biomechanical performance of selected prophylactic fixation constructs in a standardized 50% femoral neck defect model. METHODS: Thirty-five composite femora were assigned to five groups. Group A served as the intact control. A standardized 50% femoral neck defect was created in Groups B-E. Group B received isolated cement augmentation; Group C, inverted-triangle cannulated screw fixation; Group D, inverted-triangle cannulated screw fixation combined with medial plate augmentation; and Group E, dynamic hip screw fixation. All specimens underwent combined axial and torsional testing to determine axial stiffness, torsional stiffness, and failure load. FINDINGS: Groups B and C showed significantly lower axial stiffness, torsional stiffness, and failure load than the intact control group. In contrast, Groups D and E demonstrated higher mechanical values than Groups B and C, with values closer to the intact control group. The addition of medial plate augmentation to cannulated screw fixation improved construct strength compared with cannulated screw fixation alone. INTERPRETATION: In this standardized composite femur model, dynamic hip screw fixation and cannulated screw fixation combined with medial plate augmentation provided stronger biomechanical reinforcement than isolated cement augmentation or cannulated screw fixation alone. These findings should be interpreted as preclinical biomechanical data limited to a synthetic bone model and specific loading conditions.