Exercise during growth is widely recommended as a key strategy in the primary prevention of osteoporosis. This theory seems reasonable if exercise is pursued into adulthood, but perhaps not if exercise is ceased; in the latter case, the mechanostat theory predicts a decrease in bone strength due to a decrease in the largest forces applied to the skeleton. However, recent findings suggesting mai...

Obesity and type 2 diabetes mellitus (T2DM) progress worldwide with detrimental effects on several physiological systems including bone tissue mainly by affecting bone quality. Several gut hormones analogues have been proven potent in ameliorating bone quality. In the present study, we used the leptin receptor-deficient db/db mice as a model of obesity and severe T2DM to assess the extent of bo...

OBJECTIVE Exercise-induced weight loss (WL) can lead to decreased areal bone mineral density (aBMD). It is unknown whether this translates into decreased volumetric BMD (vBMD) or bone strength. The purpose of this pilot study was to determine whether exercise-induced WL results in decreased vBMD and bone strength in postmenopausal women. METHODS Fourteen subjects participated in a 4-month end...

Strategies to reduce fracture risk must be based on the understanding of the mechanisms that underline the increased incidence of fractures with age and with bone diseases that reduce bone stock. There is evidence that in addition to bone minerals density, other factors influence bone strength. This study reviews the biomechanical aspects of age-related fractures, including the interacting role...

INTRODUCTION: Mechanical analogue composite bone models have been used as cadaveric bone substitutes in a wide variety of biomechanical tests. The objective of this study was to validate the diaphyseal structural properties in terms of flexural rigidity, ultimate bending strength, axial stiffness, ultimate compression strength, ultimate torsional strength, torque angle at ultimate torsional str...

OBJECTIVE The purpose of this work was to analyze the relationship between intensity and duration of physical activity and composite indices of femoral neck strength and bone-mineral content of the femoral neck, lumbar spine, and total body. METHODS Physical activity was assessed by accelerometry in 143 girls and 150 boys (mean age: 9.7 years). Measurement of bone-mineral content, femoral nec...

OBJECTIVES To develop and determine convergent validity and reliability of a simple and inexpensive clinical test to quantify back extensor muscle strength. METHODS Two testing sessions were conducted, 7 days apart. Each session involved three trials of standing maximal isometric back extensor muscle strength using both the novel test and isokinetic dynamometry. Lumbar spine bone mineral dens...

OBJECTIVES Grip strength has been reported to be associated with bone mass locally at the forearm and also at distant skeletal sites, including the spine and hip. Less is known about the association between low grip strength and risk of vertebral fracture. The aim of this study was to examine the association between low grip strength, bone mineral density at the hip and spine, and vertebral fra...

BACKGROUND Bone quantity, quality, and turnover contribute to whole bone strength. Although bone mineral density, or bone quantity, is associated with increased fracture risk, less is known about bone quality. Various conditions, including disorders of mineral homeostasis, disorders in bone remodeling, collagen disorders, and drugs, affect bone quality. QUESTIONS/PURPOSES The objectives of th...

BACKGROUND This study was designed to derive the theoretical formulae to predict the pullout strength of pedicle screws with an inconstant outer and/or inner diameter distribution (conical screws). For the transpedicular fixation, one of the failure modes is the screw loosening from the vertebral bone. Hence, various kinds of pedicle screws have been evaluated to measure the pullout strength us...