What do we know about atypical femoral fractures? Insights and enigmas

Although the existence of atypical femoral fractures is well established and bisphosphonate therapy is thought to be a major risk factor, the underlying mechanisms are poorly understood. Epidemiological data show that atypical femoral fractures account for only a small proportion of diaphyseal subtrochanteric femoral fractures, being about 100 times less common than proximal femoral fractures. Consequently, the existence of atypical femoral fractures does not call into question the extremely favorable risk/benefit ratio of bisphosphonate therapy in patients with osteoporosis. Clearly, the number of fractures prevented by bisphosphonate therapy far exceeds the number of atypical femoral fractures potentially related to bisphosphonates

Relevance of visco-plastic theory in a multi-directional inhomogeneous granular flow

We confront a recent visco-plastic description of dense granular flows [P. Jop et al, Nature, {\bf 441} (2006) 727] with multi-directional inhomogeneous steady flows observed in non-smooth contact dynamics simulations of 2D half-filled rotating drums. Special attention is paid to check separately the two underlying fundamental statements into which the considered theory can be recast, namely (i) a single relation between the invariants of stress and strain rate tensors and (ii) the alignment between these tensors. Interestingly, the first prediction is fairly well verified over more than four decades of small strain rate, from the surface rapid flow to the quasi-static creep phase, where it is usually believed to fail because of jamming. On the other hand, the alignment between stress and strain rate tensors is shown to fail over the whole flow, what yields an apparent violation of the visco-plastic rheology when applied without care. In the quasi-static phase, the particularly large misalignment is conjectured to be related to transient dilatancy effects

Statistical mechanics of Beltrami flows in axisymmetric geometry: Equilibria and bifurcations

We characterize the thermodynamical equilibrium states of axisymmetric Euler-Beltrami flows. They have the form of coherent structures presenting one or several cells. We find the relevant control parameters and derive the corresponding equations of state. We prove the coexistence of several equilibrium states for a given value of the control parameter like in 2D turbulence [Chavanis and Sommeria, J. Fluid Mech. 314, 267 (1996)]. We explore the stability of these equilibrium states and show that all states are saddle points of entropy and can, in principle, be destabilized by a perturbation with a larger wavenumber, resulting in a structure at the smallest available scale. This mechanism is therefore reminiscent of the 3D Richardson energy cascade towards smaller and smaller scales. Therefore, our system is truly intermediate between 2D turbulence (coherent structures) and 3D turbulence (energy cascade). We further explore numerically the robustness of the equilibrium states with respect to random perturbations using a relaxation algorithm in both canonical and microcanonical ensembles. We show that saddle points of entropy can be very robust and therefore play a role in the dynamics. We evidence differences in the robustness of the solutions in the canonical and microcanonical ensembles. A scenario of bifurcation between two different equilibria (with one or two cells) is proposed and discussed in connection with a recent observation of a turbulent bifurcation in a von Karman experiment [Ravelet et al., Phys. Rev. Lett. 93, 164501 (2004)].Comment: 25 pages; 16 figure

Subcritical crack growth in fibrous materials

We present experiments on the slow growth of a single crack in a fax paper sheet submitted to a constant force $F$. We find that statistically averaged crack growth curves can be described by only two parameters : the mean rupture time $\tau$ and a characteristic growth length $\zeta$. We propose a model based on a thermally activated rupture process that takes into account the microstructure of cellulose fibers. The model is able to reproduce the shape of the growth curve, the dependence of $\zeta$ on $F$ as well as the effect of temperature on the rupture time $\tau$. We find that the length scale at which rupture occurs in this model is consistently close to the diameter of cellulose microfibrils

Assessment of the response profile to hyaluronic acid plus sorbitol injection in patients with knee osteoarthritis: post hoc analysis of a 6-month randomized controlled trial

peer reviewe

Identification of hip fracture patients from radiographs using Fourier analysis of the trabecular structure: a cross-sectional study

Peer reviewedPublisher PD

Male osteoporosis: diagnosis and fracture risk evaluation

Male osteoporosis is challenging to diagnose and to treat. Underestimation of the risk of male osteoporosis, the combined presence of several interwoven causative factors in many patients, and uncertainty regarding the absorptiometry cutoffs associated with fractures are major obstacles to the diagnosis of male osteoporosis and to the identification of men at risk for fractures. The lifetime risk of osteoporotic fracture is estimated at 15% among men older than 50 years. One-third of proximal femoral fractures occur in men, and the associated mortality rate is 2- to 3-fold that in women. In men, nearly half the cases of osteoporosis are related to disease, medications, or risk factors. Although the criteria for diagnosing male osteoporosis are not agreed on, the definitions developed by the World Health Organization can be used provided the reference population is composed of young males. An absorptiometry T-score < or = -2.5 is useful for diagnosing osteoporosis but fails to adequately predict the fracture risk. The identification of men at high risk for fractures requires a combined evaluation of bone mineral density data, clinical risk factors, and risk factors for falls

The osteoporosis treatment gap in patients at risk of fracture in European primary care : a multi-country cross-sectional observational study

Summary This study in 8 countries across Europe found that about 75% of elderly women seen in primary care who were at high risk of osteoporosis-related fractures were not receiving appropriate medication. Lack of osteoporosis diagnosis appeared to be an important contributing factor. Introduction Treatment rates in osteoporosis are documented to be low. We wished to assess the osteoporosis treatment gap in women ≥ 70 years in routine primary care across Europe. Methods This cross-sectional observational study in 8 European countries collected data from women 70 years or older visiting their general practitioner. The primary outcome was treatment gap: the proportion who were not receiving any osteoporosis medication among those at increased risk of fragility fracture (using history of fracture, 10-year probability of fracture above country-specific Fracture Risk Assessment Tool [FRAX] thresholds, T-score ≤ − 2.5). Results Median 10-year probability of fracture (without bone mineral density [BMD]) for the 3798 enrolled patients was 7.2% (hip) and 16.6% (major osteoporotic). Overall, 2077 women (55%) met one or more definitions for increased risk of fragility fracture: 1200 had a prior fracture, 1814 exceeded the FRAX threshold, and 318 had a T-score ≤ − 2.5 (only 944 received a dual-energy x-ray absorptiometry [DXA] scan). In those at increased fracture risk, the median 10-year probability of hip and major osteoporotic fracture was 11.2% and 22.8%, vs 4.1% and 11.5% in those deemed not at risk. An osteoporosis diagnosis was recorded in 804 patients (21.2%); most (79.7%) of these were at increased fracture risk. The treatment gap was 74.6%, varying from 53% in Ireland to 91% in Germany. Patients with an osteoporosis diagnosis were found to have a lower treatment gap than those without a diagnosis, with an absolute reduction of 63%. Conclusions There is a large treatment gap in women aged ≥ 70 years at increased risk of fragility fracture in routine primary care across Europe. The gap appears to be related to a low rate of osteoporosis diagnosis

Cost-effectiveness model of using zoledronic acid once a year versus current treatment strategies in postmenopausal osteoporosis

OBJECTIVES: To compare effectiveness, associated cost of outcomes and cost-effectiveness of a single annual infusion of zoledronic acid versus current treatment strategies plans for postmenopausal osteoporosis in France. METHODS: Twelve simulation-based models were built to investigate three types of fractures: vertebral (VF), non-vertebral excluding hip (NVF) and hip (HF), comparing two groups: zoledronic acid and current postmenopausal antiosteoporotic treatment strategies. Two effectiveness comparability assumptions have been tested: specific agent efficacy values, and same standard efficacy values for all active agents. Direct medical costs included drug costs, medical visits, monitoring and fracture management. Adherence levels were integrated into the model under the assumption that non-adherent patients had treatment effects similar to the levels of placebo effectiveness. RESULTS: Using the most conservative assumption (same standard efficacy values for all active agents), zoledronic acid strategy results in less vertebral, non-vertebral and hip fractures than other current antiosteoporotic treatment options over 3 years: 12.04% vs. 14.18%, 10.61% vs. 11.28% and 2.82% vs. 4.64% respectively, (p<0.001). In addition, zoledronic acid is more cost-effective than the current treatment strategies in all types of fractures (p<0.001): 1497 euros vs. 1685 euros per VF avoided, 1337 euros vs. 1404 euros per NVF avoided and 1216 euros vs. 1323 euros per HF avoided. CONCLUSION: Zoledronic acid is a cost-effective treatment strategy regardless of fracture type or effectiveness comparability assumptions

2012 update of French guidelines for the pharmacological treatment of postmenopausal osteoporosis

OBJECTIVES: To update the evidence-based position statement published by the French National Authority for Health (HAS) in 2006 regarding the pharmacological treatment of postmenopausal osteoporosis, under the auspices of the French Society for Rheumatology and Groupe de Recherche et d\u27Information sur les Ostéoporoses (GRIO), and with the participation of several learned societies (Collège National des Gynécologues et Obstétriciens Français, Groupe d\u27Étude de la Ménopause et du Vieillissement hormonal, Société Française de Chirurgie Orthopédique, Société Française d\u27Endocrinologie, and Société Française de Gériatrie et de Gérontologie). METHODS: A multidisciplinary panel representing the spectrum of clinical specialties involved in managing patients with postmenopausal osteoporosis developed updated recommendations based on a systematic literature review conducted according to the method advocated by the HAS. RESULTS: The updated recommendations underline the need for osteoporosis pharmacotherapy in women with a history of severe osteoporotic fracture. In these patients, any osteoporosis medication can be used; however, zoledronic acid is the preferred first-line medication after a hip fracture. In patients with non-severe fractures or no fractures, the appropriateness of osteoporosis pharmacotherapy depends on the bone mineral density and FRAX(®) values; any osteoporosis medication can be used, but raloxifene and ibandronate should be reserved for patients at low risk for peripheral fractures. Initially, osteoporosis pharmacotherapy should be prescribed for 5 years. The results of the evaluation done at the end of the 5-year period determine whether further treatment is in order. CONCLUSIONS: These updated recommendations are intended to provide clinicians with clarifications about the pharmacological treatment of osteoporosis