Biomechanical properties of the newly-designed femoral self-locking nail with bevels / 中华创伤骨科杂志

ABSTRACT

Objective To introduce a new design of interlocking system which is easy in use, makes the distal fracture fragments well aligned and rigidly fixated, reduces exposure to radiation for the surgeon and patient, and allows for a decrease in operating time. Methods The new interlocking system was designed to be a self-locking nail with bevels (b-SLN). According to the bevel principle, the axial force of the nail should be turned into a transverse force so as to control the transverse nail's movement. 10 dry-bone simples were made into the fracture model of the middle-femur to test the prototype nail. The retention of the nail in the intramedullary cavity was evaluated by the radiogram. The mechanical properties of a simulated model of single leg loading were tested on the instron-1342 type MTS. Results The prototype nail performed well as designed. The process was stable and reliable. The retention in the intramedullary cavity was fine. The shearing force between the transverse nail and main nail was enough to cut anything around them. The mechanical properties of b-SLN were similar to those of the Grosse-Kempf nail, better than auto fork compress locked intramedullary nail, and much better than MHUA nail and Ender's nail. Conclusions The structure of b-SLN is simple and reliable. There is no focus-point under stress. Its biomechanic properties are satisfactory. It is easy to use with no need of fluoroscopes in the operating theatre.