A new intramedullary nailing device for the treatment of femoral shaft fractures: A biomechanical study

Background The treatment of choice for early mobilization of femoral fractures is surgery, which traditionally employs plates and screws or intramedullary nails. We examined the biomechanical properties of a new femoral nail system. The new intramedullary propping nailing system, made of a stainless-steel alloy, consists of a nail shaft, inner rod, tensile screw, end cape and two interlocked screws. Methods Intramedullary propping nailing biomechanics was compared with that of the Grosse and Kempf nail when securing transverse fractures in 10 pairs of cadaveric femurs. The axial compressive, bending, torsional stiffness, and strain values were calculated. Findings The intramedullary propping nailing system had torsional stiffness (0.50 Nm/°) and bending stiffness (699.74 and 670.84 N/mm of lateral and frontal bending, respectively) comparable with the Grosse and Kempf nail (0.35 Nm/°, 644.85 and 606.32 N/mm of lateral and frontal bending, respectively). Intramedullary propping nailing system produced a significantly higher compressive stiffness (1.67 and 1.50 × 106 N/mm, respectively) than the Grosse and Kempf nail in the medial and anterior aspects (0.86 and 1.32 × 106 N/mm, respectively). Although no significance was found in comparison with Grosse and Kempf of the strain of each aspect, intramedullary propping nailing system yielded a significantly better-distributed strain (F = 1.007, P = 0.401). Interpretation Biomechanically, the intramedullary propping nailing system is safe and able to provide good abutment of the nail to the bone. The intramedullary propping nailing system produces a more extensive and tight contact between the nail and bone than the application of Grosse and Kempf nail.