Bone Hardness of Different Anatomical Regions of Human Radius and its Impact on the Pullout Strength of Screws

摘要

Objective To investigate the bone hardness of different anatomical regions of the human radius and its impact on the pullout strength of screws. Methods Fresh radius bones were obtained from three donated cadavers. They were divided into three parts: proximal metaphysis, shaft, and distal metaphysis. The proximal metaphysis contains the head, neck, and radial tuberosity. The distal metaphysis includes the palmaris radius and the styloid process. The shaft of the radius was divided into nine segments of equal length. The bone hardness of three radiuses, one from each cadaver, was measured by Vickers microindentation hardness tests, and the screw pullout strength was examined in the other three radiuses using a materials testing machine. The trend between radius hardness and pullout strength was analyzed by using an analysis of variance randomized block design. Pearson correlation analysis was performed to evaluate the linear correlation between the bone hardness and the pullout strength of the human radius. Results The mean hardness ranged from 33.30?HV (the head) to 43.82?HV (the diaphysis). The hardest part of the radius was the shaft, with a value of 42.54 ± 5.59?HV. The proximal metaphysis had a hardness value of 34.15 ± 6.48?HV, and the distal metaphysis hardness value was 35.24 ± 5.17?HV. The shaft was 23.5% harder than the proximal metaphysis and 20% harder than the distal metaphysis. The microhardness test demonstrated that the bone hardness value of the diaphysis was significantly higher than those of both the proximal and distal metaphysis of the radius (both P Conclusions Bone hardness and screw pullout strength are higher in the diaphysis of the radius than at either end. The pullout strength is positively related to bone hardness in the human radius.