Bone Abstracts

Fractures of the hip are serious complications associated with osteoporosis. In previous work we found evidence of osteoblast dysfunction in middle aged men with idiopathic osteoporosis. The aim of this study was to investigate gene expression and bone microarchitecture in bone samples derived from elderly men with osteoporotic hip fractures. Femoral heads and adjacent bone tissue from 12 men with low-trauma hip fractures (mean age 82±7 years) and consecutive surgical hip replacement were collected. Femoral heads from age matched men with osteoarthritis served as controls. One half of the femoral head was subjected to gene expression analysis of osteoblast related genes by RT-PCR. From the second half of the femoral head bone samples from four regions (central and subcortical region of the femoral head and neck) were analyzed by static histomorphometry. We could show a significantly decreased expression of the osteoblast related genes runx2 (−2.43-fold, P=0.004), osterix (−7.63-fold, P<0.001), and sclerostin (−7.74-fold, P=0.001) in bone samples from hip fracture patients (n=9, mean age 82±7 years) compared to controls. Osteoporotic bone samples were characterized by a significant decrease of bone volume (BV/TV: 40.1%, P=0.008) and a significant increase of trabecular separation and marrow cavity volume in the subcortical region of the neck (TbSp: 76.6%, P=0.031 and MaV/TV: 37.2%, P=0.005)) (n=10, mean age 83±6 years). In conclusion, decreased local gene expression of runx2 and osterix in men with hip fractures strongly supports the concept of osteoblast dysfunction in male osteoporosis. Microstructural changes in the trabecular structure associated with osteoporotic hip fractures in men are localized in the subcortical region of the femoral neck and are characterized by loss of trabeculae.