Abstract
Fractures of the proximal femur have significant effects on the quality of life. Secure stability is essential for aged people because their bone is fragile, osteoporotic and less resilience than young people. To obtain the stability, previous studies have primarily investigated the optimal screw designs. However, it is expected that the optimization of pilot hole size for a screw can easily improve initial stability after osteosynthesis. We investigated the effective hole size to improve the initial stability using porcine proximal femurs. Four different cancellous screws were inserted into the pilot holes with different diameters. Then, screw pullout tests were performed. It was found that there is no significant difference in the insertion torques measured during inserting screws into the specimens and pullout loads for three hole sizes. There was the difference in the pullout loads by the difference of the screw thread length. The pullout forces were positively correlated with the torques.
