Fractures in obese postmenopausal women: prevalence, skeletal location, and risk factors
Recent studies revealed that a high prevalence of obesity was reported in postmenopausal women with fragility fractures. This finding is in contrast with the general belief that obesity is protective against fractures. Compston and collaborators [1] compared prevalence and location of fractures in 57555 obese and nonobese women aged ≥55 years from 723 primary physician practices in 10 different countries. Obese women represent 23.8% of the subjects and fracture prevalence was 23% for obese and 24% for nonobese subgroups. Although prevalence is similar in both subgroups, obese women are more likely to present fractures in the upper arm, ankle, upper leg, and lower leg. In contrast, they present significantly less fractures in wrist, hip, and pelvis compared with nonobese women. Obese women with high prevalent fractures are specifically more likely to be cortisone users, present early menopause, report fair or poor general health, need arms to assist standing from sitting position and have reported at least two falls in the past year.
Strontium ranelate improves implant osseointegration
Endosseous implantation is a frequent procedure in orthopedics and dentistry, particularly in the aging population. The incidence of implant failure, however, is high in situations where the bone at the site of implantation is not of optimal quality and quantity. Alterations in bone turnover and changes in intrinsic bone tissue quality have potentially negative effects on optimal osseointegration. Strontium ranelate, which acts on both resorption and formation and improves biomaterial properties, is hypothesized to improve osseointegration, and this hypothesis was tested here [1]. Titanium implants were inserted into the proximal tibias of 30 6-month-old Sprague–Dawley female rats. During the 8 weeks following implantation, animals received orally strontium ranelate (SrRan) 5 days a week (625 mg/kg/day) or saline vehicle. Pull-out strength, μCT, and nanoindentation were assessed on the implanted tibias.
Overexpression of osteoprotegerin suppressed bone resorption and increased vertebral bone volume, density, and strength
Osteoporosis is characterized by a progressive reduction of bone mass which usually results from an imbalance between bone formation and bone resorption. Osteoclastogenesis is a tightly regulated process. A crucial step of osteoclast formation is the binding of RANKL (Receptor Activating NFkB Ligand) on its receptor RANK in osteoclast precursors. Osteoprotegerin (OPG) is a decoy RANK receptor which binds RANKL thereby preventing its interaction with RANK. Therefore, OPG reduces osteoclast differentiation and bone resorption, and has emerged as a potential treatment for osteoporosis. Indeed, transgenic mice overexpressing OPG have increased bone mass. However, long-term effects of osteoprotegerin expression on bone biomechanical properties and health have not been studied so far.
FGF23: a novel predictor of fracture risk in elderly men
A normal mineral metabolism is mandatory for skeletal development and preservation of bone integrity. Fibroblast growth factor-23 (FGF23) is a bone-derived circulating factor that decreases serum concentrations of inorganic phosphorous (Pi) and 1,25-dihydroxy vitamin D3 (1,25(OH)2D3). Increased FGF23 expression is a direct or indirect culprit in several skeletal disorders; however the relationship between FGF23 and fracture risk remains undetermined. The authors of a recent study [1] evaluated the prospective relationship between serum intact FGF23 and fracture risk, employing the Swedish part of the population-based, Osteoporotic Fractures in Men Study (MrOS) (n=2868; mean age 75.4 ± 3.2; median follow-up period 3.35 years).
HIV infection: an important cause of secondary osteoporosis
The devastating mortality associated with HIV infection has been dramatically reduced by highly active antiretroviral therapies (HAART). However, this has led to increasing numbers of HIV-infected patients living with comorbidities, including metabolic diseases. Low bone mass and osteoporosis were implicated as consequences of HAART approximately 10 years ago but fracture data in HIV-infected populations are rare. A well-characterized cohort of HIV-infected adults attending one UK centre for outpatient care was surveyed [1]. Trained nurses administered a questionnaire which enquired about previous fractures, demographic factors, lifestyle factors, diet and exercise, exposure to glucocorticoids and other drugs affecting bone mineral and HIV factors. Exposure to HAART, stage of HIV infection and status of viral load, CD4 counts were collated.
 Download here the slide set presented by Prof. Friedlander, on Thursday, November 10th. |
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