The problem with stating definitely that vertebroplasty and kyphoplasty are safe and effective procedures is the lack of comparative, blinded, randomized clinical trials. Standardized evaluative methods should be adopted.

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Compliant flooring represents a promising but understudied strategy for reducing impact force and hip fracture risk due to falls in high-risk environments such as nursing homes, hospitals, gymnasiums, and senior centers. We conducted ''pelvis release experiments'' with young women (n ¼ 15) to determine whether floor stiffness influences peak hip impact force during safe, low-height falls. During the trials, we used a pelvic sling and electromagnet to lift and instantly release the participant from a height of 5 cm above a force plate, which measured the force applied to the hip region during impact. Trials were conducted for rigid floor conditions and with layers of ethylene vinyl acetate foam rubber overlying the floor that we regarded as firm (1.5-cm thick; stiffness ¼ 263 kN/m), semifirm (4.5-cm thick; stiffness ¼ 95 kN/m), semisoft (7.5-cm thick; stiffness ¼ 67 kN/m), and soft (10.5-cm thick; stiffness ¼ 59 kN/m). When compared to the rigid condition, peak hip impact force averaged 8% lower in the firm condition and 15% lower in the semifirm condition. Peak forces were not significantly different between the semifirm, semisoft, and soft floor conditions, indicating that a 4.5 cm-thick foam mat provides nearly the same force attenuation as a 10.5 cm-thick mat. These results support the need for laboratory experiments to measure the effect of floor stiffness on postural stability and for clinical trials to determine the effect of compliant flooring on hip fracture incidence in high-risk environments. ß

ObjectivesBone loss remains a primary health concern for astronauts, despite in-flight exercise. We examined changes in bone microarchitecture, density and strength before and after long-duration spaceflight in relation to biochemical markers of bone turnover and exercise.MethodsSeventeen astronauts had their distal tibiae and radii imaged before and after space missions to the International Space Station using high-resolution peripheral quantitative CT. We estimated bone strength using finite element analysis and acquired blood and urine biochemical markers of bone turnover before, during and after spaceflight. Pre-flight exercise history and in-flight exercise logs were obtained. Mixed effects models examined changes in bone and biochemical variables and their relationship with mission duration and exercise.ResultsAt the distal tibia, median cumulative losses after spaceflight were −2.9% to −4.3% for bone strength and total volumetric bone mineral density (vBMD) and −0.8% to −2.6% for trabecular vBMD, bone volume fraction, thickness and cortical vBMD. Mission duration (range 3.5–7 months) significantly predicted bone loss and crewmembers with higher concentrations of biomarkers of bone turnover before spaceflight experienced greater losses in tibia bone strength and density. Lower body resistance training volume (repetitions per week) increased 3–6 times in-flight compared with pre-spaceflight. Increases in training volume predicted preservation of tibia bone strength and trabecular vBMD and thickness.ConclusionsFindings highlight the fundamental relationship between mission duration and bone loss. Pre-flight markers of bone turnover and exercise history may identify crewmembers at greatest risk of bone loss due to unloading and may focus preventative measures.

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Vertebral cement augmentation can restore the stiffness and strength of a fractured vertebra and relieve chronic pain. Previous finite element analysis, biomechanical tests and clinical studies have indirectly associated new adjacent vertebral fractures following augmentation to altered loading.

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