Bicondylar Tibial Plateau Fractures: What Predicts Infection?

OBJECTIVES: The purpose of this study was to identify the patient, injury, and treatment factors associated with infection of bicondylar plateau fractures and to evaluate whether center variation exists. DESIGN: Retrospective review. SETTING: Eighteen academic trauma centers. PATIENTS/PARTICIPANTS: A total of 1,287 patients with 1,297 OTA type 41-C bicondylar tibia plateau fractures who underwent open reduction and internal fixation were included. Exclusion criteria were follow-up less than 120 days, insufficient documentation, and definitive treatment only with external fixation. INTERVENTION: Open reduction and internal fixation. MAIN OUTCOME MEASUREMENTS: Superficial and deep infection. RESULTS: One hundred one patients (7.8%) developed an infection. In multivariate regression analysis, diabetes (DM) (OR [odds ratio] 3.24; P ≤ 0.001), alcohol abuse (EtOH) (OR 1.8; P = 0.040), dual plating (OR 1.8; P ≤ 0.001), and temporary external fixation (OR 2.07; P = 0.013) were associated with infection. In a risk-adjusted model, we found center variation in infection rates (P = 0.030). DISCUSSION: In a large series of patients undergoing open reduction and internal fixation of bicondylar plateau fractures, the infection rate was 7.8%. Infection was associated with DM, EtOH, combined dual plating, and temporary external fixation. Center expertise may also play a role because one center had a statistically lower rate and two trended toward higher rates after adjusting for confounders. LEVEL OF EVIDENCE: Level IV-Therapeutic retrospective cohort study.

Bone bruising severity after anterior cruciate ligament rupture predicts elevation of chemokine MCP-1 associated with osteoarthritis.

PURPOSE: Anterior cruciate ligament rupture is associated with characteristic bone contusions in approximately 80% of patients, and these have been correlated with higher pain scores. Bone bruising may indicate joint damage that increases inflammation and the likelihood of posttraumatic osteoarthritis. We sought to characterize the severity of bone bruising following acute anterior cruciate ligament injury and determine if it correlates with synovial fluid and serum levels of the proinflammatory chemokine monocyte chemoattractant protein-1 associated with posttraumatic osteoarthritis. METHODS: This was a retrospective analysis of data collected prospectively from January 2014 through December 2016. All patients who sustained an acute ligament rupture were evaluated within 15 days of injury, obtained a magnetic resonance imaging study, and underwent bone-patellar-tendon-bone autograft reconstruction were offered enrollment. The overall severity of bone bruising on magnetic resonance imaging was graded (sum of 0-3 grades in 13 sectors of the articular surfaces). Serum and synovial fluid levels of monocyte chemoattractant protein-1 were measured within 14 days of injury, and serum levels were again measured 6 and 12 months following surgery. Separate univariate linear regression models were constructed to determine the association between monocyte chemoattractant protein-1 and bone bruising severity at each time point. RESULTS: Forty-eight subjects were included in this study. They had a mean age of 21.4 years and were 48% female. Median overall bone bruising severity was 5 (range 0-14). Severity of bone bruising correlated with higher synovial fluid concentrations of monocyte chemoattractant protein-1 preoperatively (R2 = 0.18, p = 0.009) and with serum concentrations at 12 months post-reconstruction (R2 = 0.12, p = 0.04). CONCLUSIONS: The severity of bone bruising following anterior cruciate ligament rupture is associated with higher levels of the proinflammatory cytokine monocyte chemoattractant protein-1 in synovial fluid acutely post-injury and in serum 12-months following anterior cruciate ligament reconstruction. This suggests that severe bone bruising on magnetic resonance imaging after ligament rupture may indicate increased risk for persistent joint inflammation and posttraumatic osteoarthritis. LEVEL OF EVIDENCE: III - retrospective cohort study.

Musculoskeletal Health Literacy is Associated With Outcome and Satisfaction of Total Knee Arthroplasty.

BACKGROUND: The purpose of this study was to investigate if there is an association between musculoskeletal health literacy with outcome and satisfaction after total knee arthroplasty (TKA). METHODS: A cross-sectional study was performed at our tertiary center to include patients between one and six years postoperatively after primary TKA. Patients were provided a survey including basic demographics, validated musculoskeletal health literacy scale (Literacy in Musculoskeletal Problems), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and TKA satisfaction (whether they would choose to undergo the same operation again). Patients were categorized as either low or normal health literacy based on number of questions (cutoff 6 out of 9) answered correctly on the Literacy in Musculoskeletal Problems. Statistical analysis included multivariate regression with significance at P < .05. RESULTS: Four hundred fifty-three individuals fully completed the survey of eligible participants. Two hundred ninety-six individuals (65.3%) had normal health literacy, and one hundred fifty-seven individuals (34.7%) had low health literacy. Average WOMAC (/96) was 18.0 ± 19.7 in the low and 12.1 ± 15.4 in the normal health literacy groups. Patients with low health literacy had significantly higher WOMAC (worse function) than those with normal health literacy (P = .001). Patients with normal musculoskeletal health literacy were significantly more likely to undergo the same operation again (P = .01, odds ratio 2.163). CONCLUSION: This study shows that patients with low musculoskeletal health literacy have worse outcome scores and are less likely to be satisfied with their TKA. By identifying these patients preoperatively, emphasis can be placed on enhancing procedure expectations and understanding to improve outcome measures and overall satisfaction.

Hybrid input-output analysis of embodied energy security.

National energy security depends on a stable network of international trade in not only primary energy (e.g., crude oil and natural gas) and secondary energy (electricity), but also embodied energy. The latter consists of both direct energy used to directly produce a final good (e.g., crude oil used to make synthetic rubber), and indirect energy incorporated in intermediate goods and services used to make a final product (e.g., coal used to smelt iron into steel that goes into the frames of cars). While studies have analyzed international trade in embodied energy, the global flow of the indirect component of this energy has not been explicitly examined. Here we develop and apply a new hybrid input-output database of energy flows within and among the world's largest 136 economies so as to compare and contrast energy security metrics of indirect energy against direct energy. We find that 23% of the world's embodied energy network is comprised of trade linkages in indirect energy between primary energy producing countries and other countries with which they do not have direct trade ties. We also find that the global economy is 90% more dependent on imports of indirect energy than direct energy and, unsurprisingly, that countries generally have many more trading partners in indirect energy than they do in direct energy. These differences in energy security metrics are assessed at the global, sectoral, and national levels over the years 2000-2015. The differences point to critical intermediary country nodes in the global trade network of indirect energy, principally the United States, China, and Russia.

Abiotic hydrogen (H2) sources and sinks near the Mid-Ocean Ridge (MOR) with implications for the subseafloor biosphere.

Free hydrogen (H2) is a basal energy source underlying chemosynthetic activity within igneous ocean crust. In an attempt to systematically account for all H2 within young oceanic lithosphere (<10 Ma) near the Mid-Ocean Ridge (MOR), we construct a box model of this environment. Within this control volume, we assess abiotic H2 sources (∼6 × 1012 mol H2/y) and sinks (∼4 × 1012 mol H2/y) and then attribute the net difference (∼2 × 1012 mol H2/y) to microbial consumption in order to balance the H2 budget. Despite poorly constrained details and large uncertainties, our analytical framework allows us to synthesize a vast body of pertinent but currently disparate information in order to propose an initial global estimate for microbial H2 consumption within young ocean crust that is tractable and can be iteratively improved upon as new data and studies become available. Our preliminary investigation suggests that microbes beneath the MOR may be consuming a sizeable portion (at least ∼30%) of all produced H2, supporting the widely held notion that subseafloor microbes voraciously consume H2 and play a fundamental role in the geochemistry of Earth's ocean-atmosphere system.

Differentiating the Effects of Climate Change-Induced Temperature and Streamflow Changes on the Vulnerability of Once-Through Thermoelectric Power Plants.

Thermoelectric power plants with once-through cooling systems generated 30% (∼300 GW) of U.S. electricity in 2016. Factors that reduce once-through cooling capacity and thus power output are environmental regulations, warming surface waters, and drought. The latter two may become more frequent as global climate changes. Previous research indicates that reduction in power plant capacity caused by environmental regulations can be significant while that by surface water warming is minor. Here, we address the effect of droughts on power output, which until now has remained conflated with temperature impacts. We do this using a widely used electricity generation model alongside hourly operational and meteorological data for 52 once-through plants located across the U.S. The effect of drought on plant output is examined for different water-availability and temperature scenarios, with and without regulations on plant water discharge. We find that if surface waters warm 3 °C and river discharges drop 20%, droughts would account for ≤20% of total capacity reduction depending on the plant, warming surface waters ≤2.3%, and environmental regulations up to 80%. This suggests that maintaining environmental regulations will require the continued conversion of plant cooling systems from once-through to recirculating, and mitigating climate impacts will require more stringent drought-specific watershed management.

Effects of Environmental Temperature Change on the Efficiency of Coal- and Natural Gas-Fired Power Plants.

Modeling studies predict that droughts and hotter water and air temperatures caused by climate warming will reduce the efficiency (η) of thermoelectric plants by 0.12-0.45% for each 1 °C of warming. We evaluate these predictions using historical performance data for 39 open- and closed-loop coal and natural gas plants from across the U.S., which operated under daily and seasonal temperature fluctuations multiples greater than future average warming projections. Seven to 14 years of hourly water (Tw), dry-bulb air (Ta), and wet-bulb air (Twb) temperature recordings collected near each plant are regressed against efficiency to attain estimates of Δη per 1 °C increase. We find reductions in η with increased Tw (for open-loop plants) up to 1 order of magnitude less than previous estimates. We also find that changes in η associated with changes in Ta (open-loop plants) or Twb (closed-loop plants) are not only smaller than previous estimates but also variable; i.e., η rises with Ta or Twb for some plants and falls for others. Our findings suggest that thermoelectric plants, particularly closed-loop plants, should be more resilient to climate warming than previously expected.

Residential Solar PV Systems in the Carolinas: Opportunities and Outcomes.

This paper presents a first-order analysis of the feasibility and technical, environmental, and economic effects of large levels of solar photovoltaic (PV) penetration within the services areas of the Duke Energy Carolinas (DEC) and Duke Energy Progress (DEP). A PV production model based on household density and a gridded hourly global horizontal irradiance data set simulates hourly PV power output from roof-top installations, while a unit commitment and real-time economic dispatch (UC-ED) model simulates hourly system operations. We find that the large generating capacity of base-load nuclear power plants (NPPs) without ramping capability in the region limits PV integration levels to 5.3% (6510 MW) of 2015 generation. Enabling ramping capability for NPPs would raise the limit of PV penetration to near 9% of electricity generated. If the planned retirement of coal-fired power plants together with new installations and upgrades of natural gas and nuclear plants materialize in 2025, and if NPPs operate flexibly, then the share of coal-fired electricity will be reduced from 37% to 22%. A 9% penetration of electricity from PV would further reduce the share of coal-fired electricity by 4-6% resulting in a system-wide CO2 emissions rate of 0.33 to 0.40 tons/MWh and associated abatement costs of 225-415 (2015$ per ton).

Additional Post-Concussion Impact Exposure May Affect Recovery in Adolescent Athletes.

Repeat concussion has been associated with risk for prolonged and pronounced clinical recovery in athletes. In this study of adolescent athletes, we examined whether an additional head impact within 24 h of a sports-related concussion (SRC) is associated with higher symptom burden and prolonged clinical recovery compared with a single-injury group. Forty-two student-athletes (52% male, mean age = 14.9 years) diagnosed with an SRC in a concussion clinic were selected for this study: (1) 21 athletes who sustained an additional significant head impact within 24 h of the initial injury (additional-impact group); (2) 21 single-injury athletes, age and gender matched, who sustained only one discrete concussive blow to the head (single-injury group). Groups did not differ on initial injury characteristics or pre-injury risk factors. The effect of injury status (single- vs. additional-impact) was examined on athlete- and parent-reported symptom burden (at first clinic visit) and length of recovery (LOR). Higher symptom burden was reported by the athletes and parents in the additional-impact group at the time of first visit. The additional-impact group also had a significantly longer LOR compared with the single-injury group. These findings provide preliminary, hypothesis-generating evidence for the importance of immediate removal from play following an SRC to protect athletes from re-injury, which may worsen symptoms and prolong recovery. The retrospective study design from a specialized clinical sample points to the need for future prospective studies of the relationship between single- and additional-impact injuries on symptom burden and LOR.

Academic effects of concussion in children and adolescents.

OBJECTIVE: The aim of this work is to study the nature and extent of the adverse academic effects faced by students recovering from concussion. METHOD: A sample of 349 students ages 5 to 18 who sustained a concussion and their parents reported academic concerns and problems (eg, symptoms interfering, diminished academic skills) on a structured school questionnaire within 4 weeks of injury. Postconcussion symptoms were measured as a marker of injury severity. Results were examined based on recovery status (recovered or actively symptomatic) and level of schooling (elementary, middle, and high school). RESULTS: Actively symptomatic students and their parents reported higher levels of concern for the impact of concussion on school performance (P < .05) and more school-related problems (P < .001) than recovered peers and their parents. High school students who had not yet recovered reported significantly more adverse academic effects than their younger counterparts (P < .05). Greater severity of postconcussion symptoms was associated with more school-related problems and worse academic effects, regardless of time since injury (P < .001). CONCLUSIONS: This study provides initial evidence for a concussion's impact on academic learning and performance, with more adverse effects reported by students who had not yet recovered from the injury. School-based management with targeted recommendations informed by postinjury symptoms may mitigate adverse academic effects, reduce parent and student concerns for the impact of the injury on learning and scholastic performance, and lower the risk of prolonged recovery for students with active postconcussion symptoms.

Fuel prices, emission standards, and generation costs for coal vs natural gas power plants.

Low natural gas prices and stricter, federal emission regulations are promoting a shift away from coal power plants and toward natural gas plants as the lowest-cost means of generating electricity in the United States. By estimating the cost of electricity generation (COE) for 304 coal and 358 natural gas plants, we show that the economic viability of 9% of current coal capacity is challenged by low natural gas prices, while another 56% would be challenged by the stricter emission regulations. Under the current regulations, coal plants would again become the dominant least-cost generation option should the ratio of average natural gas to coal prices (NG2CP) rise to 1.8 (it was 1.42 in February 2012). If the more stringent emission standards are enforced, however, natural gas plants would remain cost competitive with a majority of coal plants for NG2CPs up to 4.3.

Effects of well spacing on geological storage site distribution costs and surface footprint.

Geological storage studies thus far have not evaluated the scale and cost of the network of distribution pipelines that will be needed to move CO(2) from a central receiving point at a storage site to injection wells distributed about the site. Using possible injection rates for deep-saline sandstone aquifers, we estimate that the footprint of a sequestration site could range from <100 km(2) to >100,000 km(2), and that distribution costs could be <$0.10/tonne to >$10/tonne. Our findings are based on two models for determining well spacing: one which minimizes spacing in order to maximize use of the volumetric capacity of the reservoir, and a second that determines spacing to minimize subsurface pressure interference between injection wells. The interference model, which we believe more accurately reflects reservoir dynamics, produces wider well spacings and a counterintuitive relationship whereby total injection site footprint and thus distribution cost declines with decreasing permeability for a given reservoir thickness. This implies that volumetric capacity estimates should be reexamined to include well spacing constraints, since wells will need to be spaced further apart than void space calculations might suggest. We conclude that site-selection criteria should include thick, low-permeability reservoirs to minimize distribution costs and site footprint.

Physical, chemical, and mineralogical characteristics of a reservoir sediment delta (Lake Powell, U.S.A.) and implications for water quality during low water level.

Lake Powell is a large reservoir in Utah and Arizona that has experienced large changes in water level during a recent drought. As a first step in assessing the connection between hydrologic and chemical changes at Lake Powell, we characterized the particle size and solid-phase bulk concentrations for 31 elements and 25 minerals in sediment from the inflow region and some shoreline locations by using laser diffractometry, X-ray fluorescence, elemental analysis, and X-ray diffraction Our results are consistent with previous results that show a negative correlation between particle size and concentrations of most elements and most minerals other than quartz and some feldspars. In our samples, however, solid-phase iron, rather than particle size or organic carbon, is the best predictor variable for the solid-phase concentrations of elements and minerals. Sediment characteristics vary on a scale of tens of kilometers, with fine sediment that is enriched in trace elementsnearer to the dam. These trends allow formulation of an algorithm for determining a water-level threshold below which sediment resuspension may alter water chemistry in a generic reservoir with a long and narrow sediment delta.

Physical and economic potential of geological CO2 storage in saline aquifers.

Carbon sequestration in sandstone saline reservoirs holds great potential for mitigating climate change, but its storage potential and cost per ton of avoided CO2 emissions are uncertain. We develop a general model to determine the maximum theoretical constraints on both storage potential and injection rate and use it to characterize the economic viability of geosequestration in sandstone saline aquifers. When applied to a representative set of aquifer characteristics, the model yields results that compare favorably with pilot projects currently underway. Over a range of reservoir properties, maximum effective storage peaks at an optimal depth of 1600 m, at which point 0.18-0.31 metric tons can be stored per cubic meter of bulk volume of reservoir. Maximum modeled injection rates predict minima for storage costs in a typical basin in the range of $2-7/ ton CO2 (2005 U.S.$) depending on depth and basin characteristics in our base-case scenario. Because the properties of natural reservoirs in the United States vary substantially, storage costs could in some cases be lower or higher by orders of magnitude. We conclude that available geosequestration capacity exhibits a wide range of technological and economic attractiveness. Like traditional projects in the extractive industries, geosequestration capacity should be exploited starting with the low-cost storage options first then moving gradually up the supply curve.