Bone Biomechanical Property Deterioration Due to Tobacco Smoke Exposure

Tobacco smoking has been implicated in the development of osteoporosis and early onset of menopause in women smokers. We measured various biomechanical properties of femurs and tibiae obtained from smoke-exposed and control mice to determine cigarette smoke influences on bone mass, structure, and strength. Growing female C57BL mice were exposed to sidestream cigarette smoke in a whole-body exposure chamber, set at 30 ± 2 mg smoke particulates/m³ for 4 hours/day and 5 days/week for 12 consecutive weeks. Elevated levels of urinary cotinine and pulmonary ethoxyresorufin deethylase activity in smoke-exposed mice confirmed their effective exposure to cigarette smoke. There were no differences in body weight and physical size (length, medial-lateral and anterior-posterior widths, midshaft cortical area and thickness) of femurs and tibiae between smoke-exposed and control mice. The femoral mid-shaft yield load, stiffness, yield stress, and modulus were, respectively 8%, 13%, 10%, and 14% lower (P < 0.05) in smoke-exposed compared to control mice. The ultimate load and stress in mid-shaft femurs showed decreasing trends (P < 0.1) in smoke-exposed mice. In the femoral neck, the ultimate load and stiffness were 9% and 12% lower (P < 0.05) in smoke-exposed mice, respectively. Further, the ash-to-dry bone weight ratio was smaller (∼6%, P < 0.05), and micro-computed tomographic scanning of distal femoral bone volume/total volume (%) and trabecular thickness showed decreasing trends in smoke-exposed mice compared to the control group. We conclude that exposure to tobacco smoke deteriorates some of the biomechanical properties of bone in growing female mice.