title: Statistical analysis of biomechanical properties of the adult skull and age-related structural changes by sex in a Japanese forensic sample.
abstract: The purpose of this research was to investigate the biomechanical properties of the adult human skull and the structural changes that occur with age in both sexes. The heads of 94 Japanese cadavers (54 male cadavers, 40 female cadavers) autopsied in our department were used in this research. A total of 376 cranial samples, four from each skull, were collected. Sample fracture load was measured by a bending test. A statistically significant negative correlation between the sample fracture load and cadaver age was found. This indicates that the stiffness of cranial bones in Japanese individuals decreases with age, and the risk of skull fracture thus probably increases with age. Prior to the bending test, the sample mass, the sample thickness, the ratio of the sample thickness to cadaver stature (ST/CS), and the sample density were measured and calculated. Significant negative correlations between cadaver age and sample thickness, ST/CS, and the sample density were observed only among the female samples. Computerized tomographic (CT) images of 358 cranial samples were available. The computed tomography value (CT value) of cancellous bone which refers to a quantitative scale for describing radiodensity, cancellous bone thickness and cortical bone thickness were measured and calculated. Significant negative correlation between cadaver age and the CT value or cortical bone thickness was observed only among the female samples. These findings suggest that the skull is substantially affected by decreased bone metabolism resulting from osteoporosis. Therefore, osteoporosis prevention and treatment may increase cranial stiffness and reinforce the skull structure, leading to a decrease in the risk of skull fractures.
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: number60188@chiba-u.jp.
authors.forename: Suguru
authors.initials: S
authors.lastname: Torimitsu
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan. Electronic address: y.nishida@aist.go.jp.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Nishida
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan. Electronic address: t.takano@amail.plala.or.jp.
authors.forename: Tachio
authors.initials: T
authors.lastname: Takano
authors.affiliation: Designing Everyday Life Function and Social System Team, Digital Human Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan. Electronic address: y.koizumi@aist.go.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Koizumi
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan; Department of Radiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: ymakino-tky@umin.ac.jp.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Makino
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: yajima.d@faculty.chiba-u.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yajima
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: moo600@faculty.chiba-u.jp.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Hayakawa
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: goinokuchi@graduate.chiba-u.jp.
authors.forename: Go
authors.initials: G
authors.lastname: Inokuchi
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: tsunetoa@graduate.chiba-u.jp.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Motomura
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Chiba
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: chibafumico@chiba-u.jp.
authors.forename: Katsura
authors.initials: K
authors.lastname: Otsuka
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Odo
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. Electronic address: iwase@faculty.chiba-u.jp.
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Iwase
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D044466:Asian People; D015519:Bone Density / Q000502:physiology*; D002102:Cadaver; D005260:Female; D018732:Forensic Anthropology; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D012727:Sex Characteristics; D012886:Skull / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology*; D012887:Skull Fractures / Q000503:physiopathology*; D013314:Stress, Mechanical
keywords: Bone stiffness; Cranial thickness; Osteoporosis.; Sex difference; Skull fracture; Structure change