Atlas of Human Skeleton Hardness Obtained Using the Micro‐indentation Technique

Abstract

Objectives: Measure and systematically evaluate the distribution of microhardness in the human skeleton.Methods: Three fresh corpses were obtained, aged 62 (male), 45 (female), and 58 years (male). Soft tissues were removed, and all axial and unilateral appendicular bones were freshly harvested. All three skeletons were examined by Xray and computed tomography (CT) to exclude skeletal pathology. Only bones from donors with no known skeletal pathology were included in the study. Axial and unilateral appendicular skeleton bones from each of the three donors were obtained, except for ear ossicles, hyoid bone, tailbone, and 14 phalanges of the foot, for which samples were difficult to obtain. Precision bone specimens with a thickness of 3 mm, which were cut with a Buehler IsoMet 11-1280-250 lowspeed diamond saw (Buehler, USA), were obtained from all important anatomic sites in a direction perpendicular to the mechanical axis of each bone. Micro-indentation (the Vickers hardness test) was performed on the surface of each specimen using a microhardness tester with a diamond indenter. Hardness value (HV) was computed for each indentation. Each bone specimen was divided into several regions of interest. Indentations were carefully made and computed. Then we analyzed the data to identify hardness distribution rules at different anatomic sites.Results: In total, 5360 indentations were made in 1072 regions of interest in each donor. Hardness of the axial and appendicular bones were all inhomogeneous depending on the anatomic sites, but the distribution of microhardness followed certain rules. The mean hardness value ranged from 24.46 HV (HV = hardness value, kgf/mm 2 ) for the sacrum to 53.20 HV for the shaft of the tibia. The diaphysis was harder than the metaphysis, and the proximal and distal epiphysis had lower values (8.85%-40.39%) than the diaphysis. Among the long bone diaphyses, the tibia cortical bone (51.20 HV) was the hardest, harder than the humerus (47.25 HV), the ulna (43.26 HV), the radius (42.54 HV), and the femur (47.53 HV). However, in some anatomic sites such as the lumbar vertebra (cortical bone 32.86 HV, cancellous bone 31.25 HV), the cortical shells were sometimes not harder than the internal cancellous bones. The lumbar vertebra (32.86 HV) was harder than the cervical vertebra (28.51 HV) and the thoracic vertebra (29.01 HV). Conclusions:The distribution of microhardness in the human skeleton follows certain rules. These distribution rules could be used to predict the mechanical properties of bone and progress in this field could provide data for the basis of a new three-dimensional printing technique, which may lead to new perspectives for custom-made implants.

Biomechanical Characteristics and Analysis Approaches of Bone and Bone Substitute Materials

“…As one of the most important properties of bone, bone hardness includes elastic deformation and plastic deformation. The nanoindentation method was used to measure the hardness of human bones, which provided valuable data for the preparation of bone repair materials (Table 1) [19][20][21][22][23]. The bone has several irregular marrow cavities due to its structure.…”

Third-generation biodegradable bone implants: A novel Mg-1Zn-0.5Sc alloy treated by laser shock peening to improve its characteristics

“…The hardest cortical bone hardness was in the range of 40-51.2 HV. 75 Hence, the LSP-treated Mg-1Zn-0.5Sc alloy can be beneficial for bone-implant application.…”

Primary Cooperative Application of a LARS® Tube and 3D‐Printed Prosthesis for Reconstruction of the Distal Radius after en bloc Resection of Giant Cell Tumor of Bone: A Comparative Retrospective Study

“…To the best of our knowledge, the successful application of a hernia mesh wrapping an FA has only been introduced in a case report 23 . Three‐dimensional printing technology has promoted enormously the development of basic orthopedic investigations in the past decade 24–27 . However, relatively few studies based on this emerging technology have been conducted in clinical musculoskeletal oncology, in which major investigations focus on the reconstruction of the spine, pelvis and diarthrosis in the lower extremities 28–30 .…”

“…23 Three-dimensional printing technology has promoted enormously the development of basic orthopedic investigations in the past decade. [24][25][26][27] However, relatively few studies based on this emerging technology have been conducted in clinical musculoskeletal oncology, in which major investigations focus on the reconstruction of the spine, pelvis and diarthrosis in the lower extremities. [28][29][30] Based on a review of the relevant literature, 3D-printed prostheses have been preliminarily confirmed to be an acceptable option for en bloc resection of the distal radius, showing that when applying postoperative immobilization by 4 weeks to stabilize the joint, the occurrence of postoperative complications within or approximately 1 month after surgery was 33.3%.…”