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

Abstract

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 < 0.05). The mean pullout strength values ranged from 552 N (the distal metaphysis) to 2296 N (the diaphysis). The greatest pullout strength of the radius was observed for the shaft, with a pullout strength of 1727.96 ± 111.44 N. The pullout strength of the proximal metaphysis was 726.33 ± 236.39 N, and the pullout strength of the distal metaphysis was 590.67 ± 36.30 N. The pullout strength of the shaft was 138% greater than that of the proximal metaphysis and 190% greater than that of the distal metaphysis. The pullout strength was also higher in the diaphysis than at both ends of the radius (both P < 0.05). A positive correlation was found between bone hardness and pullout strength (R = 0.927, P < 0.001). 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.

Validity of the use of porcine bone in forensic cut mark studies

“…In the femur, the cortical bone was hardest in the middle of the diaphysis with hardness values around 15‐21% higher than the proximal and distal regions, but this was not replicated in the humerus where cortical bone in the distal region was significantly harder than the proximal region (Figure 4). This mirrors the patterns observed in earlier work on human cortical bone where Evans & Lebow (23) found that the human femur is also hardest in the middle third of the shaft, and the work by Wu et al who found similar patterns of hardness in the human radius (22). Weaver (15) noted little variation in hardness along the length of the diaphyseal region of the human fibula but found a “pronounced” decrease in hardness in the metaphyseal and epiphyseal region.…”

“…The hardness of the porcine adult femur (52.23 ± 1.00 kg mm −2 ) was similar to the values for cortical bone from the femora of sows reported in the literature of 53.5‐61.6 kg mm −2 (17). The hardness of cortical bone from the adult porcine femur and humerus was comparable to the hardness of adult (aged 35) human fibular cortical bone (55.1 kg mm −2 ) as determined by Weaver (15), human iliac and calcaneal bone (49.30 kg mm −2 ) from older adults free from apparent bone disease (21), and by Wu et al for human radial diaphyses (43.82 mm −2 ) (22). Comparable hardness for human (39.4 kg mm −2 ) and porcine (37.1 kg mm −2 ) cortical bone has also been reported by Saville et al (13), although the values were somewhat lower than those reported in the literature for porcine and human bone, and those observed in this study.…”

Hardness, an Important Indicator of Bone Quality, and the Role of Collagen in Bone Hardness

“…Collagen cross-link formation is thought to affect the mechanical properties of bone at a material level [ 19 , 20 ]. The heterogeneity of bone porosity, collagen fiber orientation, density and mineralization lead to a gradient of bone material properties and can have a strong effect on the structural performance of bone [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

Microstructure and Porosity Evolution of the Ti–35Zr Biomedical Alloy Produced by Elemental Powder Metallurgy

“…The hardest part of the radius was the shaft, with a value of 42 ± 6 HV. The proximal metaphysis had a hardness value of 34 ± 6 HV, and the distal metaphysis hardness value was 35 ± 5 HV [ 61 , 62 , 63 ]. Generally, the hardness of material is related to its atomic mobility capacity, distortion of crystalline lattice and atomic displacement.…”