Biomechanical comparison of different fixations of femur-interlocking-nails

Objective. A new design of intra-medullary nailing fixation is investigated in this study. The strength properties of the new design are compared to the standard fixation method. Design. The bone-implant-compound is examined by using experimental methods. Background. Failure of bone substance in the region of the interlocking screws is a complication in particular in treating fractures of osteoporotic bone. A new additional implant is investigated, which should improve the fracture fixation of the bone-implant-compound. Methods. The experiments were performed by using an universal testing machine. The bone-implant-compound was loaded by different compressive forces and the stiffness of the bone-implant-compound was measured. The maximum force to failure was also determined by a destructive test. Results. The experimental results indicate that the additional implant increases the stiffness of the bone-implant-compound. The highest stress concentrations occur at the drill holes of the interlocking screws. Failure of the bone-implant-compound occurs at higher maximum forces by using the additional implant. Conclusions. The additional implant improves the strength of the bone-implant-compound. In the case of osteoporotic bone, the use of the additional implant is recommended.