title: Trabecular bone status in ultradistal tibia under habitual gait loading: a pQCT study in postmenopausal women.
abstract: This study investigated regional volumetric trabecular bone mineral density (tBMD) and bone area at the ultradistal tibia in Chinese women using peripheral quantitative computed tomography. Fifty-six postmenopausal women aged 47-62 yr participated in BMD measurements at baseline and 22 of them were followed at both 1-yr and 3-yr follow-up scans. Regional baseline tBMD, rate of annual bone loss, and trabecular bone area were determined. Baseline measurements showed that the tBMD of both the posterior (252.9+/-63.4 mg/cm(3)) and medial (226.6+/-68.9 mg/cm(3)) regions was significantly higher than that of the anterior (126.3+/-61.9 mg/cm(3)) and lateral regions (149.8+/-50.6 mg/cm(3)), respectively (p<0.001). Both the 1-yr and 3-yr follow-up measurements showed that there was significant physiological annual tBMD loss on an average of 1.61%, at the four regions. Inter-slice regional tBMD and trabecular bone area measurements demonstrated a significant linear decrease from the distal to proximal aspects (p<0.001). Findings suggest that dynamic compressive loading during the heel strike and the body weight vector shifting toward the medial aspect during the stance phase in a normal gait might account for the regional tBMD differences. Increased tBMD and bone area toward the distal tibial endplate may adapt to withstand the axial impact loading. However, the low-impact weight-bearing nature of a normal gait may not be osteogenic to prevent regional bone loss. An exercise program specific to the women at risk should be contemplated.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, PR China.
authors.forename: Yau-Ming
authors.initials: YM
authors.lastname: Lai
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Vivian Wing-Yin
authors.initials: VW
authors.lastname: Hung
authors.forename: Wing-Yee
authors.initials: WY
authors.lastname: Choy
authors.forename: Suk-Tak
authors.initials: ST
authors.lastname: Chan
authors.forename: Lawrence Wing-Chi
authors.initials: LW
authors.lastname: Chan
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chan
mesh_terms: D000222:Adaptation, Physiological; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology; D013977:Tibia / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016138:Walking / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology