Conditioning of stochastic 3-D fracture networks to hydrological and geophysical data

The geometry and connectivity of fractures exert a strong influence on the flow and transport properties of fracture networks. We present a novel approach to stochastically generate three-dimensional discrete networks of connected fractures that are conditioned to hydrological and geophysical data. A hierarchical rejection sampling algorithm is used to draw realizations from the posterior probability density function at different conditioning levels. The method is applied to a well-studied granitic formation using data acquired within two boreholes located 6 m apart. The prior models include 27 fractures with their geometry (position and orientation) bounded by information derived from single-hole ground-penetrating radar (GPR) data acquired during saline tracer tests and optical televiewer logs. Eleven cross-hole hydraulic connections between fractures in neighboring boreholes and the order in which the tracer arrives at different fractures are used for conditioning. Furthermore, the networks are conditioned to the observed relative hydraulic importance of the different hydraulic connections by numerically simulating the flow response. Among the conditioning data considered, constraints on the relative flow contributions were the most effective in determining the variability among the network realizations. Nevertheless, we find that the posterior model space is strongly determined by the imposed prior bounds. Strong prior bounds were derived from GPR measurements and helped to make the approach computationally feasible. We analyze a set of 230 posterior realizations that reproduce all data given their uncertainties assuming the same uniform transmissivity in all fractures. The posterior models provide valuable statistics on length scales and density of connected fractures, as well as their connectivity. In an additional analysis, effective transmissivity estimates of the posterior realizations indicate a strong influence of the DFN structure, in that it induces large variations of equivalent transmissivities between realizations. The transmissivity estimates agree well with previous estimates at the site based on pumping, flowmeter and temperature data.

A meta-analysis of the association of fracture risk and body mass index in women.

Several recent studies suggest that obesity may be a risk factor for fracture. The aim of this study was to investigate the association between body mass index (BMI) and future fracture risk at different skeletal sites. In prospective cohorts from more than 25 countries, baseline data on BMI were available in 398,610 women with an average age of 63 (range, 20-105) years and follow up of 2.2 million person-years during which 30,280 osteoporotic fractures (6457 hip fractures) occurred. Femoral neck BMD was measured in 108,267 of these women. Obesity (BMI ≥ 30 kg/m(2) ) was present in 22%. A majority of osteoporotic fractures (81%) and hip fractures (87%) arose in non-obese women. Compared to a BMI of 25 kg/m(2) , the hazard ratio (HR) for osteoporotic fracture at a BMI of 35 kg/m(2) was 0.87 (95% confidence interval [CI], 0.85-0.90). When adjusted for bone mineral density (BMD), however, the same comparison showed that the HR for osteoporotic fracture was increased (HR, 1.16; 95% CI, 1.09-1.23). Low BMI is a risk factor for hip and all osteoporotic fracture, but is a protective factor for lower leg fracture, whereas high BMI is a risk factor for upper arm (humerus and elbow) fracture. When adjusted for BMD, low BMI remained a risk factor for hip fracture but was protective for osteoporotic fracture, tibia and fibula fracture, distal forearm fracture, and upper arm fracture. When adjusted for BMD, high BMI remained a risk factor for upper arm fracture but was also a risk factor for all osteoporotic fractures. The association between BMI and fracture risk is complex, differs across skeletal sites, and is modified by the interaction between BMI and BMD. At a population level, high BMI remains a protective factor for most sites of fragility fracture. The contribution of increasing population rates of obesity to apparent decreases in fracture rates should be explored. © 2014 American Society for Bone and Mineral Research.

Femur fracture in preschool children : experience with flexible intramedullary nailing in 72 children

RESUME Fractures du fémur chez les enfants d'âge préscolaire. Expérience avec l'enclouage centromédullaire élastique stable chez 72 enfants Introduction L'immobilisation plâtrée est le traitement le plus fréquemment utilisé pour traiter les fractures du fémur chez les enfants d'âge préscolaire de moins de 6 ans. L'enclouage centromédullaire élastique stable (ECMES), qui a remplacé les immobilisations plâtrées chez les enfants d'âge scolaire, est une alternative qui n'a jamais été étudiée spécifiquement dans la tranche d'âge préscolaire. Matériel et Méthode Nous avons réalisé une étude rétrospective de tous les cas de fractures du fémur chez l'enfant de moins de 6 ans traitées par ECMES dans le service de chirurgie pédiatrique du Centre Hospitalier Universitaire Vaudois et de l'Hôpital de l'Enfance de Lausanne sur une période de 15 ans. Résultats Parmi les 210 fractures du fémur traitées par ECMES entre le 1.1.1988 et le 31.12.2003, 74 fractures du fémur ont été identifiées chez 73 enfants âgés de 1.5 à 5.9 ans. Ces fractures étaient sous-trochantériennes (n=5), diaphysaires (n=64, dont 5 ouvertes), ou métaphysaires discales (n=4). Le type de fracture était transverse (n=35, dont 2 ouvertes), oblique (n=28, dont 3 ouvertes) au spiroïde (n=11). Quatre fractures étaient comminutives. Le temps opératoire moyen était de 56,9 minutes (limites entre 20 et 155 min.) pour les enfants ne présentant pas d'autre pathologie chirurgicale. Le séjour hospitalier moyen était de 9.1 jours (limites entre 1 et 46 jours) pour tous les enfants n'ayant pas de pathologie associée. Chez les enfants sans lésion ou pathologie associée, la première mise en charge s'est effectuée en moyenne au 14,1 ème jour post-opératoire (limites entre 1 et 42ème jour) alors que la première mobilisation a eu lieu en moyenne dès le 2,7ème jour post-opératoire (limites entre le 1 et le 14ème jour). 64 enfants ont été suivis à long terme avec un recul moyen de. 36,8 mois (limites entre 4 et 124 mois). Nous avons relevés 6 enfants avec une inégalité de longueur de plus d'un centimètre, alors que nous n'avons jamais constaté de défaut de rotation. Durant le 11 premières années de l'étude, 9 enfants ont dû être réopérés pour raccourcissement secondaire de broches extériorisées ou douloureuses sous la peau. Aucun problème de broche n'a été observé après introduction d'une nouvelle pince à couper. 2 réductions de fracture se sont faites à foyer ouvert. Une infection localisée transitoire du point de ponction d'une broche a été notée, sans ostéite associée. Discussion L' ECMES chez le petit enfant est techniquement réalisable sans véritable limite inférieure d'âge. Il favorise la mobilisation et la charge précoces. Les complications sont avant tout en rapport avec la technique et peuvent être évitées. Les résultats sont au moins aussi bons et meilleurs sur certains points que ceux publiés en utilisant les immobilisations. En outre ce traitement évite une longue hospitalisation. Conclusions L'ECMES peut être appliqué aux enfants de moins de 6 ans avec les mêmes bénéfices que ceux observés pour les plus grands, sans en augmenter la morbidité. La limite inférieure d'âge reste à déterminer. Un suivi à long terme s'impose pour vérifier l'absence d'inégalité de longueur des membres inférieurs.

Official Positions for FRAX(®) clinical regarding glucocorticoids: the impact of the use of glucocorticoids on the estimate by FRAX(®) of the 10 year risk of fracture from Joint Official Positions Development Conference of the International Society for Clinical Densitometry and International Osteoporosis Foundation on FRAX(®).

Given the significant impact the use of glucocorticoids can have on fracture risk independent of bone density, their use has been incorporated as one of the clinical risk factors for calculating the 10-year fracture risk in the World Health Organization's Fracture Risk Assessment Tool (FRAX(®)). Like the other clinical risk factors, the use of glucocorticoids is included as a dichotomous variable with use of steroids defined as past or present exposure of 3 months or more of use of a daily dose of 5 mg or more of prednisolone or equivalent. The purpose of this report is to give clinicians guidance on adjustments which should be made to the 10-year risk based on the dose, duration of use and mode of delivery of glucocorticoids preparations. A subcommittee of the International Society for Clinical Densitometry and International Osteoporosis Foundation joint Position Development Conference presented its findings to an expert panel and the following recommendations were selected. 1) There is a dose relationship between glucocorticoid use of greater than 3 months and fracture risk. The average dose exposure captured within FRAX(®) is likely to be a prednisone dose of 2.5-7.5 mg/day or its equivalent. Fracture probability is under-estimated when prednisone dose is greater than 7.5 mg/day and is over-estimated when the prednisone dose is less than 2.5 mg/day. 2) Frequent intermittent use of higher doses of glucocorticoids increases fracture risk. Because of the variability in dose and dosing schedule, quantification of this risk is not possible. 3) High dose inhaled glucocorticoids may be a risk factor for fracture. FRAX(®) may underestimate fracture probability in users of high dose inhaled glucocorticoids. 4) Appropriate glucocorticoid replacement in individuals with adrenal insufficiency has not been found to increase fracture risk. In such patients, use of glucocorticoids should not be included in FRAX(®) calculations.

La cohorte OstéoLaus: évaluation des outils de routine clinique pour la prédiction de la fracture ostéoporotique [OsteoLaus: prediction of osteoporotic fractures by clinical risk factors and DXA, IVA and TBS].

OsteoLaus is a cohort of 1400 women 50 to 80 years living in Lausanne, Switzerland. Clinical risk factors for osteoporosis, bone ultrasound of the heel, lumbar spine and hip bone mineral density (BMD), assessment of vertebral fracture by DXA, and microarchitecture evaluation by TBS (Trabecular Bone Score) will be recorded. TBS is a new parameter obtained after a re-analysis of a DXA exam. TBS is correlated with parameters of microarchitecture. His reproducibility is good. TBS give an added diagnostic value to BMD, and predict osteoporotic fracture (partially) independently to BMD. The position of TBS in clinical routine in complement to BMD and clinical risk factors will be evaluated in the OsteoLaus cohort.

Acetylcholinesterase inhibitors and healing of hip fracture in Alzheimer's disease patients: a retrospective cohort study.

OBJECTIVES This study was designed to assess effects of cholinergic stimulation using acetylcholinesterase inhibitors (AChEIs), a group of drugs that stimulate cholinergic receptors and are used to treat Alzheimer's disease (AD), on healing of hip fractures. METHODS A retrospective cohort study was performed using 46-female AD patients, aged above 75 years, who sustained hip fractures. Study analyses included the first 6-months after hip fracture fixation procedure. Presence of AChEIs was used as predictor variable. Other variables that could affect study outcomes: age, body mass index (BMI), mental state or type of hip fracture, were also included. Radiographic union at fracture site (Hammer index), bone quality (Singh index) and fracture healing complications were recorded as study outcomes. The collected data was analyzed by student's-t, Mann-Whitney-U and chi-square tests. RESULTS No significant differences in age, BMI, mental state or type of hip fracture were observed between AChEIs-users and nonusers. However, AChEIs-users had better radiographic union at the fracture site (relative risk (RR),2.7; 95%confidence interval (CI),0.9-7.8), better bone quality (RR,2.0; 95%CI,1.2-3.3) and fewer healing complications (RR,0.8; 95%CI,0.7-1.0) than nonusers. CONCLUSION In elderly female patients with AD, the use of AChEIs might be associated with an enhanced fracture healing and minimized complications.

Role of mental disorders in nosocomial infections after hip fracture treatment.

The association between mental disorders (MDs) and iatrogenic complications after hip fracture surgery has been poorly studied. Among iatrogenic complications, nosocomial infections (NIs) are a major factor in hip fracture surgery. The aim of this paper was to determine whether patients with a MD and a hip fracture develop more NIs after hip surgery than patients with no MD. We studied 912 patients who underwent surgery for a hip fracture (223 patients with a MD who underwent surgery for a hip fracture and 689 control patients without a MD who also underwent surgery for a hip fracture) and followed them after surgery. Univariable and multivariable analyses were performed using simple and multiple logistic regression analysis (confidence interval, crude and adjusted odds ratios, and P value). We found that MDs, gender, and comorbidities were not associated with a higher risk of developing a NI after surgery for a hip fracture. Only age increases the risk of a NI.

Tibio-talar arthrodesis with long anterograde nail after complex open fracture-dislocation of the ankle : P17

Introduction: Posttraumatic painful osteoarthritis of the ankle joint after fracture-dislocation often has to be treated with arthrodesis. In the presence of major soft tissue lesions and important bone loss the technique to achieve arthrodesis has to be well chosen in order to prevent hardware failure, infection of bulky implants or non-union. Methods: We present the case of a 53 year-old biker suffering of a fracture-dislocation of the ankle associated with a mayor degloving injury of the heel. After initial immobilization of the lesion by external fixation in Spain the patient was transferred to our hospital for further treatment. The degloving injury of the heel with MRSA infection was initially treated by repeated débridement, changing of the configuration of the Ex Fix and antibiotic therapy with favourable outcome. Because of the bony lesions reconstruction of the ankle-joint was juged not to be an option and arthrodesis was planned. Due to bad soft-tissue situation standard open fixtion with plate and/or screws was not wanted but an option for intramedullary nailing was taken. However the use of a standard retrograde arthrodesis nail comes with two problems: 1) Risk of infection of the heel-part of the calaneus/nail in an unstable soft tissue situation with protruding nail. And 2) talo-calcaneal arthrodesis of an initially healthy subtalar joint. Given the situation of an unstable plantar/heel flap it was decided to perform anklearthrodesis by means of an anterograde nail with static fixation in the talus and in the proximal tibia. Results:This operation was performed with minimal opening at the ankle-site in order to remove the remaining cartilage and improve direct bone to bone contact. Arthrodesis was achieved by means of an anterograde T2 Stryker tibial nail.One year after the anterograde nailing the patient walks without pain for up to 4 hours with a heel of good quality and arthrodesis is achieved. Conclusion: Tibiotalar arthrodesis in the presence of mayor soft tissue lesions and bone loss can be successfully achieved with antegrade nailing.

Medial femoral condyle fracture as a complication of antegrade intramedullary nailing.

A 49-year-old man suffered a closed oblique fracture of the middle third of his left femur. Closed reduction and internal fixation by intramedullary (IM) nailing were performed. Per-operative fluoroscopic imaging and initial postoperative X-rays were judged normal and the patient followed the usual rehabilitation protocol. At 3-month follow-up the patient still demonstrated poor knee function and pain. A plain X-ray and a CT scan of the left knee revealed a displaced fracture of the medial femoral condyle. Analysis of the postoperative imaging suggests that the fracture occurred during the insertion of the IM nail. The nail possibly hit the Steinmann traction pin in the distal femur causing the medial condyle fracture. The patient was reoperated; open reduction and internal plate and screw fixation were performed with satisfactory clinical progress postoperatively. The description and illustration of this case is intended to make trauma surgeons aware of this rare but serious complication of IM femoral nailing.