BIOMECHANICAL PROPERTIES, OSTEOPOROSIS, AND FRACTURE POTENTIAL OF METATARSAL TRABECULAR BONE FROM MOOSE IN ISLE ROYALE NATIONAL PARK

Abstract

We investigated relationships between trabecular bone mechanical properties in bone mineral density of metatarsal bones from moose (Alces alces) of known age, sex, and cause of death in Isle Royale National Park, Michigan. Bone density mineral equivalent values were determined using quantitative computed tomography scans (QCT) of 10 mm cross-sections of cancellous bone from the distal metatarsus. Cylindrical specimens were taken from the same anatomic position as the region of interest in the scan. Each specimen was weighed, measured, and photographed for trabecular microstructure under transmitted light microscopy. Using compression tests to failure, we found that modulus of elasticity of trabecular bone was significantly correlated with bone mineral density (r² = 0.91, P = 0.0005). There were also significant relationships between both apparent density and volume fraction of bone (r² = 0.75, P = 0.0001) and bone mineral density on QCT. Loss of bone mineral occurs as the result of environmental, nutritional, hormonal, and/or genetic causes and increases fracture risk. This study has implications for the understanding of moose bone fragility related to mechanical and geometric properties such as elasticity and trabecular microstructure in routine activities of daily living (forging, ambulating, and bedding-down) as well as when subjected to stressors such as kicking predators, running, and falling.