Biomechanical studies on framework and insertion of pins of external fixation

Compression, moment, and shear forces were loaded onto models of a long tubular bone with comminuted fracture fixed with external fixation using several pins and frameworks. Stabilities were compared by finite element method. For the unstable fracture, stability in all directions is necessary. The selection of pins and framework methods, as well as selection of pin insertion site, should take into account anatomical conditions, conditions of fracture part, muscle power, and direction of muscular actions. To obtain better stability, it is also good to add half pins to piercing pins and to make triangular frameworks. For the stable tibia fractures, Judet's method is simple and excellent. Adherence to a single method is not necessary. Pins, insertion method, and fixation apparatus should be selected after understanding all conditions.