Biomechanical evaluation of the percutaneous compression plating system for hip fractures

Objective: To investigate the biomechanical properties of the percutaneous compression plating system for intertrochanteric hip fractures. Design: A biomechanical laboratory investigation on human cadaveric upper femora was conducted. Setting: Biomechanical laboratory. Patients: Sixteen femora from cadavers of patients aged 60 to 85 years. Intervention: An intertrochanteric fracture was performed along the intertrochanteric line and fixed with the percutaneous compression plating system. Main Outcome Measurements: Postfixation and postcycling bending and torsional stiffnesses, and load to failure at 0, 7, and 25degrees of adduction. Result: The normalized postfixation bending and torsional stiffnesses in the neutral position were 65% and 59%, respectively, and higher with adduction. After percutaneous compression plating fixation, bending stiffness increased to 72% following cyclic loading (p < 0.05). It was comparable to that of similar fixation constructs in the literature, whereas the torsional stiffness was somewhat higher. The mode of failure was distal femoral neck sagging, indicating good femoral head fixation. No varus displacement and cutouts were observed. Conclusions: Our biomechanical data indicate that the percutaneous compression plating provides adequate bending stiffness and torsional stability. With sliding capability this fixation leads to controlled fracture impaction, which is further enhanced by cyclic loading.