Bom-Taeck Kim

University of Melbourne, Melbourne, Victoria, Australia

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Publications (3)16.21 Total impact

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    ABSTRACT: We studied 112 healthy men and 261 healthy women aged 18-92 years, and 34 men and 73 postmenopausal women with vertebral fractures aged 45-90 years to determine (i) whether patients with vertebral fractures have shorter stature before fracture, and (ii) whether the difference between arm span and standing or sitting height can be used to identify patients with fractures. Arm span was measured by using a calibrated extended ruler. Standing height, sitting height and leg length were measured by using a Holtain stadiometer. The results were expressed in absolute term and standard deviation (SD) or Z-scores (mean+/-SEM). Advancing age was associated with decreased sitting height (r=-0.37 to -0.41, both P<0.01) and a trend towards decreased arm span (r=-0.12 to -0.17, P=0.06 and 0.07) in healthy men and women; leg length was independent of age in both sexes (r=-0.09 to -0.12, NS). In patients with vertebral fractures, sitting height was reduced in women (Z=-0.83+/-0.14 SD, P<0.01) and men (Z=-1.37+/-0.21 SD, P<0.01) but only the women had reduced leg length (Z=-0.46+/-0.15 SD, P<0.01) and arm span (Z=-0.76+/-0.15 SD, P<0.01). Univariate and multivariate analyses suggest that the predictive ability of the difference between arm span and standing or sitting height to identify patients with vertebral fractures is limited. We concluded that women, not men, with vertebral fractures may come from a population with short stature. The difference between arm span and standing or sitting height cannot be used to predict vertebral fracture risk.
    Osteoporosis International 01/2004; 15(1):43-8. · 4.04 Impact Factor
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    ABSTRACT: To identify the structural and hormonal basis for the lower incidence of fractures in males than females, sex differences in femoral mid-shaft geometry and breaking strength were studied in growth hormone (GH)-replete and -deficient male and female rats. Sexual dimorphism appeared during growth. Cortical thickening occurred almost entirely by acquisition of bone on the outer (periosteal) surface in males and mainly on the inner (endocortical) surface in females. By 8 months of age, males had 22% greater bone width and 33% greater breaking strength than females. Gonadectomy (Gx) at 6 weeks reduced sex differences in bone width to 7% and strength to 21% by halving periosteal bone formation in males and doubling it in females. Gx had no net effect on the endocortical surface in males but abolished endocortical bone acquisition in females. GH deficiency halved periosteal bone formation and had no net effect on the endocortical surface in males, but abolished bone acquisition on both surfaces in females, leaving males with 17% greater bone width and 44% greater breaking strength than females. Sex hormone deficiency produces greater bone fragility in males than females by removing a stimulator of periosteal growth in males and removing an inhibitor of periosteal growth in females. GH deficiency produces less bone fragility in males than females because males retain androgen-dependent periosteal bone formation while bone acquisition on both surfaces is abolished in females. Thus, periosteal growth is independently and additively stimulated by androgens and GH in males, inhibited by estrogen, and stimulated by GH in females. The hormonal regulation of bone surfaces establishes the amount and spatial distribution of bone and so the sexual dimorphism in its strength.
    Journal of Bone and Mineral Research 02/2003; 18(1):150-5. · 6.13 Impact Factor
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    ABSTRACT: Spine fractures usually occur less commonly in men than in women. To identify the structural basis for this gender difference in vertebral fragility, we studied 1013 healthy subjects (327 men and 686 women) and 76 patients with spine fractures (26 men and 50 women). Bone mineral content (BMC), cross-sectional area (CSA), and volumetric bone mineral density (vBMD) of the third lumbar vertebral body (L3) were measured by posteroanterior (PA) and lateral scanning using dual-energy X-ray absorptiometry (DXA). In this cross-sectional study, the diminution in peak vertebral body BMC from young adulthood to old age was less in men than in women (6% vs. 27%). This diminution was the net result of two opposing changes occurring concurrently throughout adult life: the removal of bone adjacent to marrow on the inner (endosteal) surface by bone resorption and the deposition of bone on the outer (periosteal) surface by bone formation. For L3, we estimated that men resorbed 3.7 g and deposited 3.1 g, producing a net loss of 0.6 g from young adulthood to old age and women resorbed 3.1 g and deposited only 1.2 g, producing a net loss of 1.9 g. Thus, based on our indirect estimates of periosteal gain and endosteal loss across life, the observed net diminution in BMC during aging was less in men than women because absolute periosteal bone formation was greater in men than women (3.1 g vs. 1.2 g) not because absolute bone resorption was less in men. On the contrary, the absolute amount of bone resorbed was greater in men than women (3.7 g vs. 3.1 g). Periosteal bone formation also increased vertebral body CSA 3-fold more in men than in women, distributing loads onto a larger CSA, so that the load imposed per unit CSA decreased twice as much in men than in women (13% vs. 5%). In men and women with spine fractures, CSA and vBMD were reduced relative to age-matched controls. However, vBMD was no different to the adjusted vBMD in age-matched controls derived assuming controls had no periosteal bone formation during aging. Thus, large amounts of bone are resorbed in men as well as in women, accounting for the age-related increase in spine fractures in both genders. Periosteal bone formation increases CSA and offsets bone loss in both genders but more greatly in men, accounting for the lower incidence of spine fractures in men than in women. We speculate that reduced periosteal bone formation, during growth or aging, may be in part responsible for both reduced vertebral size and reduced vBMD in men and women with spine fractures. Sexual dimorphism in vertebral fragility is more the result of gender differences in age-related bone gain than age-related bone loss.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 11/2001; 16(12):2267 - 2275. · 6.04 Impact Factor