Stiffness and Endurance of a Locking Compression Plate Fixed on Fractured Femur

The effects of locking screw position (long column fixation-long distance between the nearest screws to the fracture-and short column fixation-short distance between the nearest screws to the fracture) and fracture gap size (1-mm and 8-mm transverse fracture gap) on stiffness and fatigue of fractured femur fixed with a locking compression plate (LCP) were biomechanically evaluated. The stiffness of I-mm fracture gap models and that of intact femoral model were in the range of 270-284 N/mm, while those of 8-mm fracture gap models were significantly lower (155-170 N/mm). After 1,000,000 cycles of loading, no fracture of LCP of 1-mm fracture gap models fixed in either lone, column or short column fashions occurred. On the other hand, the complete fractures of LCPs of 8-mm fracture gap models fixed in long column and short column fashions occurred after 5 1,500 and 42,000 cycles of loading, respectively. These results suggest that the full weight loading may be allowed for the patient with I-mm transverse femoral fracture fixed with an LCP. On the other hand, the full load of walking should be avoided for the patient with 8-mm transverse femoral fracture fixed with an LCP before adequate healing.