Category:
Hindfoot; Trauma; Other
Introduction/Purpose:
Calcaneal fractures are a common injury with potential for concomitant involvement of the sustentaculum tali. Common surgical repair involves a ...sinus tarsi approach with placement of a lag screw from lateral to medial. There is no current study that focuses on the potential damage to the medial structures after screw placement. The goal of this paper was to describe the incidence in which medial structures were damaged using a sinus tarsi approach for lateral to medial screw fixation of the sustentaculum tali.
Methods:
Seven fresh-frozen below-the-knee cadaver specimens were used for the present anatomic dissection study. Prior to investigations, specimens were inspected with fluoroscopic radiographs for any pathology or prior operational intervention Each specimen underwent screw placement using the sinus tarsi approach. Medial dissection of the calcaneus was performed after screw placement to determine the proximity of the anatomical structures of interest to the inserted hardware. The four anatomical structures of interest were the tibialis posterior tendon, flexor hallucis longus, flexor digitorum longus, and posterior neurovascular bundle. Distance from the 4.0 mm screw to the previously mentioned anatomic structures was measured with a scientific ruler and recorded to the nearest millimeter. The mean, standard deviation, and range for distances were calculated for all structures. Analysis of variance (ANOVA) was used to determine statistical significance.
Results:
The average patient age, height, and weight were 79.3 years, 5 feet 4 inches, and 127 lbs respectively. The primary outcome of interest was the longitudinal distance between the medial aspect of the screw to the anatomical structures of interest. On average, the posterior neurovascular bundle had the closest proximity to the medial aspect of the screw for all seven specimens with a mean distance of 6.4 mm. The second closest structure was the FHL with a mean distance of 7 mm, followed by the FDL and tibialis posterior tendon, with mean distances of 9.9 mm and 13.9 mm respectively. The posterior neurovascular bundle was hit by the screw on one occasion, whereas the hardware contacted the FDL on two separate occasions. The screw was placed through the FDL in one of the two occasions; however, the FDL was not transected or ruptured.
Conclusion:
This study sheds more light on the potential risks to medial structures when placing the sustentacular screw during open reduction and internal fixation of displaced intraarticular calcaneal fractures. We urge the orthopedic surgeon to exercise extreme caution when performing this critical step of the procedure to minimize avoidable injury to structures of importance that may increase the morbidity of the patient.
Macrophages at the base of human gut associated lymphoid tissue (GALT), become loaded early in life with dark granular pigment that is rich in aluminium, silicon, and titanium. The molecular ...characteristics, intracellular distribution, and source of this pigment is described. Laser scanning and electron microscopy showed that pigmented macrophages were often closely related to collagen fibres and plasma cells in GALT of both small and large intestine and contained numerous phagolysosomes, previously described as granules, that are rich in electron dense submicron sized particles. Morphological assessment, x ray microanalysis, and image electron energy loss spectroscopy showed three distinct types of microparticle: type I - spheres of titanium dioxide, 100-200 nm diameter, characterised as the synthetic food-additive polymorph anatase; type II - aluminosilicates, < 100-400 nm in length, generally of flaky appearance, often with adsorbed surface iron, and mostly characteristic of the natural clay mineral kaolinite; and type III - mixed environmental silicates without aluminium, 100-700 nm in length and of variable morphology. Thus, this cellular pigment that is partly derived from food additives and partly from the environment is composed of inert inorganic microparticles and loaded into phagolysosomes of macrophages within the GALT of all human subjects. These observations suggest that the pathogenicity of this pigment should be further investigated since, in susceptible individuals, the same intracellular distribution of these three types of submicron particle causes chronic latent granulomatous inflammation.
Background: The decision of whether or not to investigate for common bile duct stones before cholecystectomy utilizes clinical, laboratory, and radiologic information (indicators). There is ...tremendous individual variation among clinicians in the criteria used for making this decision. Our aim was to perform a meta-analysis of published data to estimate the performance characteristics of the most commonly used preoperative indicators of common bile duct stones.
Methods: Using predetermined exclusion criteria, we selected articles from a MEDLINE search and bibliographic review. Weighted averages were used to determine summary sensitivity, specificity, and positive and negative likelihood ratios for each indicator for stones.
Results: From 2221 citations identified, 22 studies met inclusion criteria. The 10 indicators examined were reported in a common fashion in three or more articles, and could be assessed preoperatively. Seven exhibited a specificity greater than 90%. Indicators with positive likelihood ratios of 10 or above were cholangitis, preoperative jaundice, and ultrasound evidence of common bile duct stones. Positive likelihood ratios for dilated common bile duct on ultrasound, hyperbilirubinemia, and jaundice ranged from almost 4 to almost 7. Elevated levels of alkaline phosphatase, pancreatitis, cholecystitis, and hyperamylasemia exhibited positive likelihood ratios of less than 3.
Conclusions: This meta-analysis has identified indicators for duct stones and ranked them according to likelihood ratios. These findings can be applied as guidelines for whether to investigate for duct stones before cholecystectomy. (Gastrointest Endosc 1996;44:450-9.)
A reliable method has been developed for making through-bond electrical contacts to molecules. Current-voltage curves are quantized as integer multiples of one fundamental curve, an observation used ...to identify single-molecule contacts. The resistance of a single octanedithiol molecule was 900 ± 50 megohms, based on measurements on more than 1000 single molecules. In contrast, nonbonded contacts to octanethiol monolayers were at least four orders of magnitude more resistive, less reproducible, and had a different voltage dependence, demonstrating that the measurement of intrinsic molecular properties requires chemically bonded contacts.
Transfer of angular momentum from a spin-polarized current to a ferromagnet provides an efficient means to control the magnetization dynamics of nanomagnets. A peculiar consequence of this spin ...torque, the ability to induce persistent oscillations in a nanomagnet by applying a d.c. current, has previously been reported only for spatially uniform nanomagnets. Here, we demonstrate that a quintessentially non-uniform magnetic structure, a magnetic vortex, isolated within a nanoscale spin-valve structure, can be excited into persistent microwave-frequency oscillations by a spin-polarized d.c. current. Comparison with micromagnetic simulations leads to identification of the oscillations with a precession of the vortex core. The oscillations, which can be obtained in essentially zero magnetic field, exhibit linewidths that can be narrower than 300 kHz at ~1.1 GHz, making these highly compact spin-torque vortex-oscillator devices potential candidates for microwave signal-processing applications, and a powerful new tool for fundamental studies of vortex dynamics in magnetic nanostructures. PUBLICATION ABSTRACT
Emerging data are demonstrating that tamper-resistant opioids may play an important role in changing prescription opioid abuse behaviors. This study was a chart review to examine if the reformulation ...of OxyContin® into a version with tamper-resistant properties (OxyNEO®) had an impact on oxycodone-positive urine drug screens (UDSs) in opioid-dependent patients receiving methadone maintenance therapy (MMT).
The historical element of this study examined 250 eligible charts from patients on MMT who had data during the time periods when only OxyContin was available (baseline period), during the transition to OxyNEO, and when only OxyNEO was available. The prospective element included an exploratory questionnaire regarding retrospective opioid use.
The study was conducted at three methadone clinics, in Oshawa, Peterborough, and Scarborough in Ontario, Canada.
Male and female patients were eligible if they had a diagnosis of opioid dependency, received MMT, and had at least one oxycodone-positive UDS during the baseline period.
This was a noninterventional study.
The main outcome was the number of oxycodonepositive UDSs.
The results demonstrated a marked reduction in oxycodone-positive UDSs that showed stepwise, statistically significant decreases during the transition and post-OxyContin periods relative to baseline. While the oxycodone-positive UDS results were decreasing, morphine-related-positive UDSs remained relatively stable during the same periods. There were no significant gender differences noted.
The introduction of OxyNEO was associated with a statistically significant reduction in oxycodone exposure in a population of methadone-maintained patients.
War, in human and animal societies, can be extremely costly but can also offer significant benefits to the victorious group. We might expect groups to go into battle when the potential benefits of ...victory (
) outweigh the costs of escalated conflict (
); however,
and
are unlikely to be distributed evenly in heterogeneous groups. For example, some leaders who make the decision to go to war may monopolize the benefits at little cost to themselves ('exploitative' leaders). By contrast, other leaders may willingly pay increased costs, above and beyond their share of
('heroic' leaders). We investigated conflict initiation and conflict participation in an ecological model where single-leader-multiple-follower groups came into conflict over natural resources. We found that small group size, low migration rate and frequent interaction between groups increased intergroup competition and the evolution of 'exploitative' leadership, while converse patterns favoured increased intragroup competition and the emergence of 'heroic' leaders. We also found evidence of an alternative leader/follower 'shared effort' outcome. Parameters that favoured high contributing 'heroic' leaders, and low contributing followers, facilitated transitions to more peaceful outcomes. We outline and discuss the key testable predictions of our model for empiricists studying intergroup conflict in humans and animals. This article is part of the theme issue 'Intergroup conflict across taxa'.
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