Biomechanical Performance of Locked Intramedullary Nail Systems in Comminuted Femoral Shaft Fractures

Biomechanical study of the Grosse-Kempf femoral nail

“…Our results agree with those reported by Johnson [7] and Tencer [18,19] who studied different methods of fixation of midshaft and subtrochanteric femoral fractures and concluded that the Grosse-Kempf was most affected by torsional forces.…”

Comparison of mechanical rigidity between plate augmentation leaving the nail in situ and interlocking nail using cadaveric fracture model of the femur

“…According to the experiment by Kyle et al [10], the rotational resistance could be increased up to four times using interlocking screws, and Bankston et al [1] reported it could be increased as much as ten times. However, even if rotational resistance could be increased by using interlocking screws, the rotational stiffness of an interlocking nail is only 3% of the normal femur according to the experiment by Johnson et al [6]. Thus, compared with 55-70% of bending stiffness in the normal femur, an interlocking intramedullary nail would be relatively vulnerable to rotational deformity.…”

“…Fracture healing can be achieved by the formation of peripheral callus since acceptable motion is present at the fracture site. Complications such as shortening, angulation, and rotation, especially in complex fractures, can be minimised with interlocking screws, which may be inserted transversely and/or obliquely through the nail proximal and distal to the fracture site [6,14]. However, as the interlocking intramedullary nails are not canal-filling in the distal shaft or comminuted fractures of the femur, the ability to resist rotational and bending force is limited.…”

Plate augmentation leaving the nail in situ and bone grafting for non-union of femoral shaft fractures

“…Reamed exchange nailing remains the treatment of choice for the non-union of femoral shaft fractures but a significant number of patients who undergo reamed exchange nailing require additional procedures to achieve fracture healing [4,15]. Although interlocking screws can increase the rotational resistance, the rotational stiffness of an interlocking nail is only 3% compared to 55-70% of bending stiffness of the normal femur according to Johnson et al [7]. Furthermore, according to these experiments, the fracture site did not show much resistance to rotational movement within a 10-15°angle when an interlocking intramedullary nail was inserted, suggesting that the absolute fixation power at the fracture site by an interlocking intramedullary nail, especially against rotational force, is limited.…”