Underlying the importance of trabecular architecture on whole bone strength, osteoporosis has recently been defined as “a disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk” . Architectural measures, such as the fabric tensor and connectivity, can explain 20%–30% of the inter-specimen variance in modulus of trabecular bone [2–4]. It has also been observed that apparent density alone does not fully differentiate clinically between atraumatic fracture and non-fracture subjects  and that bone strength is not increased in response to fluoride treatments despite an increase in bone mass , both suggestive of the role of architecture on the mechanical properties of trabecular bone. Most previous studies on architecture have focused on inter-specimen variations in architecture, whereas intra-specimen variations have received little attention. Thus, the intra-specimen variation in trabecular thickness is considered in this study as an additional candidate parameter for assessing osteoporosis and the effectiveness of drug treatments.