Finite element analysis of the multiple drilling technique for early osteonecrosis of the femoral head.

We used finite element (FE) method to investigate the effect of the drilling number and entry location of holes used in the multiple drilling technique on the stress and strain state in femur. Different three-dimensional FE models of a human hip joint with or without multiple drilling were fabricated using computed tomographic images obtained from the hip joint of a cadaver. The analysis technique was evaluated in a compression test using the cadaver specimen and FE analysis for the test using an FE model of the specimen. Von Mises stresses, principal stresses, and principal strains in the cancellous and cortical bone were calculated by using the different models, and changes in these values in relation to drilling number and entry hole locations were evaluated. Calculated peak values were much smaller than the yield strength, tensile strength, and yield strain of the cancellous and cortical bone for all cases of multiple drilling. Our results support that the multiple drilling technique for osteonecrosis of the femoral head is a stable operation technique.