Design and testing of a personalized noise monitoring system.

Agricultural workers are more prone to noise-induced hearing loss than are many other workers. Hearing protection device use among agricultural workers is low, but training can increase hearing protection device use. This work proposes a system designed to automatically inform agricultural workers when they were exposed to noises that exceed the National Institute for Occupational Safety and Health (NIOSH) recommended exposure level. The smartphone-based system worn on the arm uses a noise dosimeter to measure noise exposures throughout the day to within ±2 A-weighted decibels of a Class 2 sound level meter. The device collects location and audio data, which are transferred to a server and presented to the worker on a locally hosted website. The website details noise exposure and helps the worker identify where exposure occurred and what specific tasks exceed NIOSH's recommended exposure limit, putting them at higher risk of noise-induced hearing loss. With this understanding, the worker is expected to adopt behavior changes and better hearing protection use at critical places and times. This pilot study evaluates the accuracy of the noise dosimeter and GPS relative to gold-standard instruments. The system was tested on a farm with outputs compared with gold-standard instruments. A-weighted, 1-sec averaged sound pressure levels and position data were collected while users were performing a variety of tasks indoors and outdoors. The smartphone's external noise dosimeter read within ±2 A-weighted decibels of the Class 2 reference dosimeter 59% of the time. The positioning devices had an average error of sub-4 m. While not perfectly matching gold-standard instruments, the device is capable of identifying and collecting information relative to loud noise events that promote noise-induced hearing loss.

Combining physics-based and Kriging models to improve the estimation of noise exposure.

Worker exposure to occupational hazards is traditionally measured by equipping workers with wearable exposure monitors. An emerging alternative measurement first generates time-varying hazard maps from permanent monitors within the facility, then estimating worker exposure by integrating hazard levels traversed in map, following the tracked movement of workers. Complex environments may require many monitors to produce a hazard map with the necessary accuracy, but effective interpolation functions can reduce the required number of monitors needed. This work assesses the effectiveness of three models for accurately interpolating hazard levels among monitors: a traditional Kriging model, a physics-based model, and a hybrid model that combines the Kriging and physics-based models. The effectiveness of each interpolation function was tested with sound levels collected in four environmental settings. These detailed experimental data were used to generate over 10,000 simulation trials, where each trial configured the experimental data into a unique arrangement of simulated monitoring and sampling positions. For each simulation trial, the effectiveness of the three models was assessed with the root mean square error of the sound levels at the simulated sampling positions, using the simulated monitoring positions as input. The interpolated values between the monitored positions were analyzed separately from the extrapolated values beyond the monitored positions. The hybrid model consistently reported among the lowest errors in each trial. The Kriging model performed best for the densest networks (those with the most monitors). Even in these cases, the hybrid model performed within 10% of the Kriging model with less than a third of the monitors. The experiment demonstrates that the hybrid model is highly effective at estimating hazardous sound levels; future work may demonstrate similar advantages for gas and aerosol hazards.

Surgical Skill Can be Objectively Measured From Fluoroscopic Images Using a Novel Image-based Decision Error Analysis (IDEA) Score.

BACKGROUND: To advance orthopaedic surgical skills training and assessment, more rigorous and objective performance measures are needed. In hip fracture repair, the tip-apex distance is a commonly used summative performance metric with clear clinical relevance, but it does not capture the skill exercised during the process of achieving the final implant position. This study introduces and evaluates a novel Image-based Decision Error Analysis (IDEA) score that better captures performance during fluoroscopically-assisted wire navigation. QUESTIONS/PURPOSES: (1) Can wire navigation skill be objectively measured from a sequence of fluoroscopic images? (2) Are skill behaviors observed in a simulated environment also exhibited in the operating room? Additionally, we sought to define an objective skill metric that demonstrates improvement associated with accumulated surgical experience. METHODS: Performance was evaluated both on a hip fracture wire navigation simulator and in the operating room during actual fracture surgery. After examining fluoroscopic image sequences from 176 consecutive simulator trials (performed by 58 first-year orthopaedic residents) and 21 consecutive surgical procedures (performed by 19 different orthopaedic residents and one attending orthopaedic surgeon), three main categories of erroneous skill behavior were identified: off-target wire adjustments, out-of-plane wire adjustments, and off-target drilling. Skill behaviors were measured by comparing wire adjustments made between consecutive images against the goal of targeting the apex of the femoral head as part of our new IDEA scoring methodology. Decision error metrics (frequency, magnitude) were correlated with other measures (image count and tip-apex distance) to characterize factors related to surgical performance on both the simulator and in the operating room. An IDEA composite score integrating decision errors (off-target wire adjustments, out-of-plane wire adjustments, and off-target drilling) and the final tip-apex distance to produce a single metric of overall performance was created and compared with the number of hip wire navigation cases previously completed (such as surgeon experience levels). RESULTS: The IDEA methodology objectively analyzed 37,000 images from the simulator and 688 images from the operating room. The number of decision errors (7 ± 5 in the operating room and 4 ± 3 on the simulator) correlated with fluoroscopic image count (33 ± 14 in the operating room and 20 ± 11 on the simulator) in both the simulator and operating room environments (R2 = 0.76; p < 0.001 and R2 = 0.71; p < 0.001, respectively). Decision error counts did not correlate with the tip-apex distance (16 ± 4 mm in the operating room and 12 ± 5 mm on the simulator) for either the simulator or the operating room (R2 = 0.08; p = 0.15 and R2 = 0.03; p = 0.47, respectively), indicating that the tip-apex distance is independent of decision errors. The IDEA composite score correlated with surgical experience (R2 = 0.66; p < 0.001). CONCLUSION: The fluoroscopic images obtained in the course of placing a guide wire contain a rich amount of information related to surgical skill. This points the way to an objective measure of skill that also has potential as an educational tool for residents. Future studies should expand this analysis to the wide variety of procedures that rely on fluoroscopic images. CLINICAL RELEVANCE: This study has shown how resident skill development can be objectively assessed from fluoroscopic image sequences. The IDEA scoring provides a basis for evaluating the competence of a resident. The score can be used to assess skill at key timepoints throughout residency, such as when rotating onto/off of a new surgical service and before performing certain procedures in the operating room, or as a tool for debriefing/providing feedback after a procedure is completed.

Do Skills Acquired from Training with a Wire Navigation Simulator Transfer to a Mock Operating Room Environment?

BACKGROUND: Skills training and simulation play an increasingly important role in orthopaedic surgical education. The intent of simulation is to improve performance in the operating room (OR), a trait known as transfer validity. No prior studies have explored how simulator-based wire navigation training can transfer to higher-level tasks. Additionally, there is a lack of knowledge on the format in which wire navigation training should be deployed. QUESTIONS/PURPOSES: (1) Which training methods (didactic content, deliberate practice, or proficiency-based practice) lead to the greatest improvement in performing a wire navigation task? (2) Does a resident's performance using a wire navigation simulator correlate with his or her performance on a higher-level simulation task in a mock OR involving a C-arm, a radiopaque femur model, and a large soft tissue surrogate surrounding the femur? METHODS: Fifty-five residents from four different medical centers participated in this study over the course of 2 years. The residents were divided into three groups: traditional training (included first-year residents from the University of Iowa, University of Minnesota, and the Mayo Clinic), deliberate practice (included first-year residents from the University of Nebraska and the University of Minnesota), and proficiency training (included first-year residents from the University of Minnesota and the Mayo Clinic). Residents in each group received a didactic introduction covering the task of placing a wire to treat an intertrochanteric fracture, and this was considered traditional training. Deliberate practice involved training on a radiation-free simulator that provided specific feedback throughout the practice sessions. Proficiency training used the same simulator to train on specific components of wire navigation, like finding the correct starting point, to proficiency before moving to assessment. The wire navigation simulator uses a camera system to track the wire and provide computer-generated fluoroscopy. After training, task performance was assessed in a mock OR. Residents from each group were assessed in the mock OR based on their use of fluoroscopy, total time, and tip-apex distance. Correlation analysis was performed to examine the relationship between resident performance on the simulator and in the mock OR. RESULTS: Residents in the two simulation-based training groups had a lower tip-apex distance than those in the traditional training group (didactic training tip-apex distance: 24 ± 7 mm, 95% CI, 20-27; deliberate practice tip-apex distance: 16 ± 5 mm, 95% CI, 13-19, p = 0.001; proficiency training tip-apex distance: 15 ± 4 mm, 95% CI, 13-18, p < 0.001). Residents in the proficiency training group used more images than those in the other groups (didactic training: 22 ± 12 images, p = 0.041; deliberate practice: 19 ± 8 images; p = 0.012, proficiency training: 31 ± 14 images). In the two simulation-based training groups, resident performance on the simulator, that is, tip-apex distance, image use, and overall time, was correlated with performance in the mock OR (r-square = 0.15 [p = 0.030], 0.61 [p < 0.001], and 0.43 [p < 0.001], respectively). CONCLUSIONS: As residency programs are designing their curriculum to train wire navigation skills, emphasis should be placed on providing an environment that allows for deliberate practice with immediate feedback about their performance. Simulators such as the one presented in this study offer a safe environment for residents to learn this key skill. LEVEL OF EVIDENCE: Level II, therapeutic study.

Sources of error and variability in particulate matter sensor network measurements.

The quality of mass concentration estimates from increasingly popular networks of low-cost particulate matter sensors depends on accurate conversion of sensor output (e.g., voltage) into gravimetric-equivalent mass concentration, typically using a calibration procedure. This study evaluates two important sources of variability that lead to error in estimating gravimetric-equivalent mass concentration: the temporal changes in sensor calibration and the spatial and temporal variability in gravimetric correction factors. A 40-node sensor network was deployed in a heavy vehicle manufacturing facility for 8 months. At a central location in the facility, particulate matter was continuously measured with three sensors of the network and a traditional, higher-cost photometer, determining the calibration slope and intercept needed to translate sensor output to photometric-equivalent mass concentration. Throughout the facility, during three intensive sampling campaigns, respirable mass concentrations were measured with gravimetric samplers and photometers to determine correction factors needed to adjust photometric-equivalent to gravimetric-equivalent mass concentration. Both field-determined sensor calibration slopes and intercepts were statistically different than those estimated in the laboratory (α = 0.05), emphasizing the importance of aerosol properties when converting voltage to photometric-equivalent mass concentration and the need for field calibration to determine slope. Evidence suggested the sensors' weekly field calibration slope decreased and intercept increased, indicating the sensors were deteriorating over time. The mean correction factor in the cutting and shot blasting area (2.9) was substantially and statistically lower than that in the machining and welding area (4.6; p = 0.01). Therefore, different correction factors should be determined near different occupational processes to accurately estimate particle mass concentrations.

Efficacy of Paired Electrochemical Sensors for Measuring Ozone Concentrations.

Typical low-cost electrochemical sensors for ozone (O3) are also highly responsive to nitrogen dioxide (NO2). Consequently, a single sensor's response to O3 is indistinguishable from its response to NO2. Recently, a method for quantifying O3 concentrations became commercially available (Alphasense Ltd., Essex, UK): collocating a pair of sensors, a typical oxidative gas sensor that responds to both O3 and NO2 (model OX-B431) and a second similar sensor that filters O3 and responds only to NO2 (model NO2-B43F). By pairing the two sensors, O3 concentrations can be calculated. We calibrated samples of three NO2-B43F sensors and three OX-B431 sensors with NO2 and O3 exclusively and conducted mixture experiments over a range of 0-1.0 ppm NO2 and 0-125 ppb O3 to evaluate the ability of the paired sensors to quantify NO2 and O3 concentrations in mixture. Although the slopes of the response among our samples of three sensors of each type varied by as much as 37%, the individual response of the NO2-B43F sensors to NO2 and OX-B431 sensors to NO2 and O3 were highly linear over the concentrations studied (R2 ≥ 0.99). The NO2-B43F sensors responded minimally to O3 gas with statistically non-significant slopes of response. In mixtures of NO2 and O3, quantification of NO2 was generally accurate with overestimates up to 29%, compared to O3, which was generally underestimated by as much as 187%. We observed changes in sensor baseline over 4 days of experiments equivalent to 34 ppb O3, prompting an alternate method of calculating concentrations by baseline-correcting sensor signal. The baseline-correction method resulted in underestimates of NO2 up to 44% and decreases in the underestimation of O3 up to 107% for O3. Both methods for calculating gas concentrations progressively underestimated O3 concentrations as the ratio of NO2 signal to O3 signal increased. Our results suggest that paired NO2-B43F and OX-B431 sensors permit quantification of NO2 and O3 in mixture, but that O3 concentration estimates are less accurate and precise than those for NO2.

Sensor Selection to Improve Estimates of Particulate Matter Concentration from a Low-Cost Network.

Deployment of low-cost sensors in the field is increasingly popular. However, each sensor requires on-site calibration to increase the accuracy of the measurements. We established a laboratory method, the Average Slope Method, to select sensors with similar response so that a single, on-site calibration for one sensor can be used for all other sensors. The laboratory method was performed with aerosolized salt. Based on linear regression, we calculated slopes for 100 particulate matter (PM) sensors, and 50% of the PM sensors fell within ±14% of the average slope. We then compared our Average Slope Method with an Individual Slope Method and concluded that our first method balanced convenience and precision for our application. Laboratory selection was tested in the field, where we deployed 40 PM sensors inside a heavy-manufacturing site at spatially optimal locations and performed a field calibration to calculate a slope for three PM sensors with a reference instrument at one location. The average slope was applied to all PM sensors for mass concentration calculations. The calculated percent differences in the field were similar to the laboratory results. Therefore, we established a method that reduces the time and cost associated with calibration of low-cost sensors in the field.

Low-Cost, Distributed Environmental Monitors for Factory Worker Health.

An integrated network of environmental monitors was developed to continuously measure several airborne hazards in a manufacturing facility. The monitors integrated low-cost sensors to measure particulate matter, carbon monoxide, ozone and nitrogen dioxide, noise, temperature and humidity. The monitors were developed and tested in situ for three months in several overlapping deployments, before a full cohort of 40 was deployed in a heavy vehicle manufacturing facility for a year of data collection. The monitors collect data from each sensor and report them to a central database every 5 min. The work includes an experimental validation of the particle, gas and noise monitors. The R² for the particle sensor ranges between 0.98 and 0.99 for particle mass densities up to 300 μg/m³. The R² for the carbon monoxide sensor is 0.99 for concentrations up to 15 ppm. The R² for the oxidizing gas sensor is 0.98 over the sensitive range from 20 to 180 ppb. The noise monitor is precise within 1% between 65 and 95 dBA. This work demonstrates the capability of distributed monitoring as a means to examine exposure variability in both space and time, building an important preliminary step towards a new approach for workplace hazard monitoring.

An inexpensive sensor for noise.

Noise is a pervasive workplace hazard that varies spatially and temporally. The cost of direct-reading instruments for noise hampers their use in a network. The objectives for this work were to: (1) develop an inexpensive noise sensor (<$100) that measures A-weighted sound pressure levels within ±2 dBA of a Type 2 sound level meter (SLM; ∼$1,800); and (2) evaluate 50 noise sensors for use in an inexpensive sensor network. The inexpensive noise sensor consists of an electret condenser microphone, an amplifier circuit, and a microcontroller with a small form factor (28 mm by 47 mm by 9 mm) than can be operated as a stand-alone unit. Laboratory tests were conducted to evaluate 50 of the new sensors at 5 sound levels: (1) ambient sound in a quiet office; (2) 3 pink noise test signals from 65-85 dBA in 10 dBA increments; and (3) 94 dBA using a SLM calibrator. Ninety-four percent of the noise sensors (n = 46) were within ±2 dBA of the SLM for sound levels from 65-94 dBA. As sound level increased, bias decreased, ranging from 18.3% in the quiet office to 0.48% at 94 dBA. Overall bias of the sensors was 0.83% across the 75 dBA to 94 dBA range. These sensors are available for a variety of uses and can be customized for many applications, including incorporation into a stationary sensor network for continuous monitoring of noise in manufacturing environments.

Evaluation of low-cost electro-chemical sensors for environmental monitoring of ozone, nitrogen dioxide, and carbon monoxide.

Development of an air quality monitoring network with high spatio-temporal resolution requires installation of a large number of air pollutant monitors. However, state-of-the-art monitors are costly and may not be compatible with wireless data logging systems. In this study, low-cost electro-chemical sensors manufactured by Alphasense Ltd. for detection of CO and oxidative gases (predominantly O3 and NO2) were evaluated. The voltages from three oxidative gas sensors and three CO sensors were recorded every 2.5 sec when exposed to controlled gas concentrations in a 0.125-m3 acrylic glass chamber. Electro-chemical sensors for detection of oxidative gases demonstrated sensitivity to both NO2 and O3 with similar voltages recorded when exposed to equivalent environmental concentrations of NO2 or O3 gases, when evaluated separately. There was a strong linear relationship between the recorded voltages and target concentrations of oxidative gases (R2 > 0.98) over a wide range of concentrations. Although a strong linear relationship was also observed for CO concentrations below 12 ppm, a saturation effect was observed wherein the voltage only changes minimally for higher CO concentrations (12-50 ppm). The nonlinear behavior of the CO sensors implied their unsuitability for environments where high CO concentrations are expected. Using a manufacturer-supplied shroud, sensors were tested at 2 different flow rates (0.25 and 0.5 Lpm) to mimic field calibration of the sensors with zero air and a span gas concentration (2 ppm NO2 or 15 ppm CO). As with all electrochemical sensors, the tested devices were subject to drift with a bias up to 20% after 9 months of continuous operation. Alphasense CO sensors were found to be a proper choice for occupational and environmental CO monitoring with maximum concentration of 12 ppm, especially due to the field-ready calibration capability. Alphasense oxidative gas sensors are usable only if it is valuable to know the sum of the NO2 and O3 concentrations.

Objective Structured Assessments of Technical Skills (OSATS) Does Not Assess the Quality of the Surgical Result Effectively.

BACKGROUND: Performance assessment in skills training is ideally based on objective, reliable, and clinically relevant indicators of success. The Objective Structured Assessment of Technical Skill (OSATS) is a reliable and valid tool that has been increasingly used in orthopaedic skills training. It uses a global rating approach to structure expert evaluation of technical skills with the experts working from a list of operative competencies that are each rated on a 5-point Likert scale anchored by behavioral descriptors. Given the observational nature of its scoring, the OSATS might not effectively assess the quality of surgical results. QUESTIONS/PURPOSES: (1) Does OSATS scoring in an intraarticular fracture reduction training exercise correlate with the quality of the reduction? (2) Does OSATS scoring in a cadaveric extraarticular fracture fixation exercise correlate with the mechanical integrity of the fixation? METHODS: Orthopaedic residents at the University of Iowa (six postgraduate year [PGY]-1s) and at the University of Minnesota (seven PGY-1s and eight PGY-2s) undertook a skills training exercise that involved reducing a simulated intraarticular fracture under fluoroscopic guidance. Iowa residents participated three times during 1 month, and Minnesota residents participated twice with 1 month between their two sessions. A fellowship-trained orthopaedic traumatologist rated each performance using a modified OSATS scoring scheme. The quality of the articular reduction obtained was then directly measured. Regression analysis was performed between OSATS scores and two metrics of articular reduction quality: articular surface deviation and estimated contact stress. Another skills training exercise involved fixing a simulated distal radius fracture in a cadaveric specimen. Thirty residents, distributed across four PGY classes (PGY-2 and PGY-3, n = 8 each; PGY-4 and PGY-5, n = 7 each), simultaneously completed the exercise at individual stations. One of three faculty hand surgeons independently scored each performance using a validated OSATS scoring system. The mechanical integrity of each fixation construct was then assessed in a materials testing machine. Regression analysis was performed between OSATS scores and two metrics of fixation integrity: stiffness and failure load. RESULTS: In the intraarticular fracture model, OSATS scores did not correlate with articular reduction quality (maximum surface deviations: R = 0.17, p = 0.25; maximum contact stress: R = 0.22, p = 0.13). Similarly in the cadaveric extraarticular fracture model, OSATS scores did not correlate with the integrity of the mechanical fixation (stiffness: R = 0.10, p = 0.60; failure load: R = 0.30, p = 0.10). CONCLUSIONS: OSATS scoring methods do not effectively assess the quality of the surgical result. Efforts must be made to incorporate assessment metrics that reflect the quality of the surgical result. CLINICAL RELEVANCE: New objective, reliable, and clinically relevant measures of the quality of the surgical result obtained by a trainee are urgently needed. For intraarticular fracture reduction and extraarticular fracture fixation, direct physical measurement of reduction quality and of mechanical integrity of fixation, respectively, meet this need.

Internal fit of pressed and computer-aided design/computer-aided manufacturing ceramic crowns made from digital and conventional impressions.

STATEMENT OF PROBLEM: No studies have evaluated the internal adaptation of pressed and milled ceramic crowns made from digital impressions. PURPOSE: The purpose of this in vitro study was to evaluate the internal fit of pressed and milled ceramic crowns made from digital and conventional impressions. MATERIAL AND METHODS: Thirty polyvinyl siloxane (PVS) impressions and 30 Lava COS impressions made of a prepared dentoform tooth (master die) were fabricated. Thirty crowns were pressed in lithium disilicate (IPS e.max Press), and 30 crowns were milled from lithium disilicate blocks (IPS e.max CAD) (15/impression technique) with the E4D scanner and milling engine. The master die and the intaglio of the crowns were digitized with a 3-dimensional laser coordinate measurement machine. The digital master die and intaglio of each crown were merged. The distance between the die and the intaglio surface of the crown was measured at 3 standardized points. One-way ANOVA was used for statistical analysis (α=.05). RESULTS: One-way ANOVA revealed that the internal gap obtained from the Lava/press group (0.211 mm, ±SD 0.041) was significantly greater than that obtained from the other groups (P<.001), while no significant differences were found among PVS/press (0.111 mm ±SD 0.047), PVS/CAD/CAM (0.116 mm ±SD 0.02), and Lava/CAD/CAM (0.145 mm ±SD 0.024). CONCLUSIONS: The combination of the digital impression and pressed crown produced the least accurate internal fit.

3D and 2D marginal fit of pressed and CAD/CAM lithium disilicate crowns made from digital and conventional impressions.

PURPOSE: This in vitro study evaluated the 3D and 2D marginal fit of pressed and computer-aided-designed/computer-aided-manufactured (CAD/CAM) all-ceramic crowns made from digital and conventional impressions. MATERIALS AND METHODS: A dentoform tooth (#30) was prepared for an all-ceramic crown (master die). Thirty type IV definitive casts were made from 30 polyvinyl siloxane (PVS) impressions. Thirty resin models were produced from thirty Lava Chairside Oral Scanner impressions. Thirty crowns were pressed in lithium disilicate (IPS e.max Press; 15/impression technique). Thirty crowns were milled from lithium disilicate blocks (IPS e.max CAD; 15/impression technique) using the E4D scanner and milling engine. The master die and the intaglio of the crowns were digitized using a 3D laser coordinate measurement machine with accuracy of ±0.00898 mm. For each specimen a separate data set was created for the Qualify 2012 software. The digital master die and the digital intaglio of each crown were merged using best-fitting alignment. An area above the margin with 0.75 mm occlusal-gingival width circumferentially was defined. The 3D marginal fit of each specimen was an average of all 3D gap values on that area. For the 2D measurements, the marginal gap was measured at two standardized points (on the margin and at 0.75 mm above the margin), from standardized facial-lingual and mesial-distal digitized sections. One-way ANOVA with post hoc Tukey's honestly significant difference and two-way ANOVA tests were used, separately, for statistical analysis of the 3D and 2D marginal data (alpha = 0.05). RESULTS: One-way ANOVA revealed that both 3D and 2D mean marginal gap for group A: PVS impression/IPS e.max Press (0.048 mm ± 0.009 and 0.040 mm ± 0.009) were significantly smaller than those obtained from the other three groups (p < 0.0001), while no significant differences were found among groups B: PVS impression/IPS e.max CAD (0.088 mm ± 0.024 and 0.076 mm ± 0.023), C: digital impression/IPS e.max Press (0.089 mm ± 0.020 and 0.075 mm ± 0.015) and D: digital impression/IPS e.max CAD (0.084 mm ± 0.021 and 0.074 mm ± 0.026). The results of two-way ANOVA revealed a significant interaction between impression techniques and crown fabrication methods for both 3D and 2D measurements. CONCLUSIONS: The combination of PVS impression method and press fabrication technique produced the most accurate 3D and 2D marginal fits.

Fluoroscopic image-based behavior analysis can objectively explain subjective expert assessment of wire navigation skill.

Psychomotor skill and decision-making efficiency in surgical wire navigation can be objectively evaluated by analysis of intraoperative fluoroscopic image sequences. Prior work suggests that such image-based behavior analysis of operating room (OR) performance can predict performer experience level (R2 = 0.62) and agree with expert opinion (the current standard) on the quality of a final implant construct (R2 = 0.59). However, it is unclear how objective image-based evaluation compares with expert assessments for entire technical OR performances. This study examines the relationships between three key variables: (1) objective image-based criteria, (2) expert opinions, and (3) performing surgeon experience level. A paired-comparison survey of seven experts, based upon eight OR fluoroscopic wire navigation image sequences, shows that the experts' preferences are best explained by objective metrics that reflect psychomotor and decision-making behaviors which are counter-productive to successful implant placement, like image count (R2 = 0.83) and behavior tally (R2 = 0.74). One such behavior, adjustments away from goal, uniquely correlated well with all three key variables: a fluoroscopic image-based analysis composite score (R2 = 0.40), expert consensus (R2 = 0.76), and performer experience (R2 = 0.41). These results confirm that experts view less efficient technical behavior as indicative of lesser technical proficiency. While expert assessments of technical skill were reliable and consistent, neither individual nor consensus expert opinion appears to correlate with performer experience (R2 = 0.11).

The effect of field condition and shoe type on lower extremity injuries in American Football.

BACKGROUND/AIM: Considerable improvement has been made in football field surfaces and types of shoe, yet relatively few epidemiological studies have investigated their roles in the risk of football injuries. This study examined the effects of field surface, surface condition and shoe type on the likelihood of lower extremity football injuries. METHODS: Deidentified data from 188 players from one division I university football team during the 2007-2010 seasons were analysed. Lower extremity injury rate and rate ratio, along with 95% confidence limits, were calculated by football activity, playing surface condition and shoe type. RESULTS: A total of 130 lower extremity injuries were sustained, with an overall lower extremity injury rate of 33.5/10 000 athlete-sessions. The lower extremity injury rate was 2.61 times higher when the surface condition was abnormal compared with when the surface condition was normal. During games, the risk for lower extremity injury was 3.34 times higher (95% CI 1.70 to 6.56) on artificial turf compared with natural grass. However, this trend was not statistically significant in practice sessions. Furthermore, neither the number of shoe cleats nor the height of the shoe top was statistically associated with risk of lower extremity injuries. CONCLUSIONS: Football players who played on artificial turf or when the surface condition was abnormal were susceptible to lower extremity injuries. Evidence from this study suggests that further research into playing surfaces and shoe types may provide fruitful opportunities to reduce injuries to collegiate football players.

Using sensor networks to study the effect of peripatetic healthcare workers on the spread of hospital-associated infections.

BACKGROUND: Super-spreading events, in which an individual with measurably high connectivity is responsible for infecting a large number of people, have been observed. Our goal is to determine the impact of hand hygiene noncompliance among peripatetic (eg, highly mobile or highly connected) healthcare workers compared with less-connected workers. METHODS: We used a mote-based sensor network to record contacts among healthcare workers and patients in a 20-bed intensive care unit. The data collected from this network form the basis for an agent-based simulation to model the spread of nosocomial pathogens with various transmission probabilities. We identified the most- and least-connected healthcare workers. We then compared the effects of hand hygiene noncompliance as a function of connectedness. RESULTS: The data confirm the presence of peripatetic healthcare workers. Also, agent-based simulations using our real contact network data confirm that the average number of infected patients was significantly higher when the most connected healthcare worker did not practice hand hygiene and significantly lower when the least connected healthcare workers were noncompliant. CONCLUSIONS: Heterogeneity in healthcare worker contact patterns dramatically affects disease diffusion. Our findings should inform future infection control interventions and encourage the application of social network analysis to study disease transmission in healthcare settings.

A Dedicated Simulator Training Curriculum Improves Resident Performance in Surgical Management of Pediatric Supracondylar Humerus Fractures.

Background: The primary goal of including simulation in residency training is to improve technical skills while working outside of the operating room. Such simulation-related skill improvements have seldom been measured in the operating room. This is largely because uncontrolled variables, such as injury severity, patient comorbidity, and anatomical variation, can bias evaluation of an operating surgeon's skill. In this study, performance during the wire navigation phase of pediatric supracondylar humerus fracture fixation was quantitatively compared between 2 groups of orthopaedic residents: a standard training group consisting of residents who participated in a single simulator session of wire navigation training and an expanded training group consisting of residents who participated in a dedicated multifaceted wire navigation simulation training curriculum. Methods: To evaluate performance in the operating room, the full sequence of fluoroscopic images collected during wire navigation was quantitatively analyzed. Objective performance metrics included number of fluoroscopic images acquired, duration from placement of the first wire to that of the final wire, and wire spread at the level of the fracture. These metrics were measured from 97 pediatric supracondylar humerus fracture pinning surgeries performed by 28 different orthopaedic residents. Results: No differences were observed between the groups for wire spread in the final fluoroscopic images (t(94) = 0.75, p = 0.45), an important clinical objective of the surgery. Residents who received the expanded simulator training used significantly fewer fluoroscopic images (mean of 46 vs. 61 images, t(85) = 2.25, p < 0.03) and required less time from first to final wire placement (mean of 11.2 vs. 14.9 minutes, t(83) = 2.53, p = 0.013) than the standard training group. A post hoc review of Accreditation Council for Graduate Medical Education case logs for 24 cases from the standard training group and for 21 cases from the expanded training group indicated that, at the time of surgeries, residents who received expanded training had completed fewer comparable cases than residents in the standard training group (mean of 13 vs. 21, t(42) = 2.40 p = 0.02). Further regression analysis indicated that the expanded simulator training produced an effect comparable with that associated with completing 10.5 similar surgical case experiences. Conclusions: This study demonstrates that training on a wire navigation simulator can lead to improved performance in the operating room on a critical skill for all orthopaedic residents. By taking fewer images and less time while maintaining sufficient pin spread, simulator-trained residents were objectively measured to have improved performance in comparison with residents who had not participated in the pediatric elbow simulator curriculum. Clinical Relevance: As programs aim to provide safe and effective training for critical orthopaedic skills such as pinning a pediatric elbow, this study demonstrates a simulator curriculum that has demonstrated the transfer of skill from a learning environment to the operating room.

Establishing Construct Validity of a Novel Simulator for Guide Wire Navigation in Antegrade Femoral Intramedullary Nailing.

Background: Antegrade femoral intramedullary nailing (IMN) is a common orthopedic procedure that residents are exposed to early in their training. A key component to this procedure is placing the initial guide wire with fluoroscopic guidance. A simulator was developed to train residents on this key skill, building off an existing simulation platform originally developed for wire navigation during a compression hip screw placement. The objective of this study was to assess the construct validity of the IMN simulator. Methods: Thirty orthopedic surgeons participated in the study: 12 had participated in fewer than 10 hip fracture or IMN related procedures and were categorized as novices; 18 were faculty, categorized as experts. Both cohorts were instructed on the goal of the task, placing a guide wire for an IM nail, and the ideal wire position reference that their wire placement would be graded against. Participants completed 2 assessments with the simulator. Performance was graded on the distance from the ideal starting point, distance from the ideal end point, wire trajectory, duration, fluoroscopy image count, and other elements of surgical decision making. A two-way ANOVA analysis was used to analyze the data looking at experience level and trial number. Results: The expert cohort performed significantly better than the novice cohort on all metrics but one (overuse of fluoroscopy). The expert cohort had a more accurate starting point and completed the task while using fewer images and less overall time. Conclusion: This initial study shows that the IMN application of a wire navigation simulator demonstrates good construct validity. With such a large cohort of expert participants, we can be confident that this study captures the performance of active surgeons today. Implementing a training curriculum on this simulator has the potential to increase the performance of the novice level residents prior to their operating on a vulnerable patient. Level of Evidence: III.

Minimally Trained Analysts Can Perform Fast, Objective Assessment of Orthopedic Technical Skill from Fluoroscopic Images.

Skill assessment in orthopedics has traditionally relied on subjective impressions from a supervising surgeon. The feedback derived from these tools may be limited by bias and other practical issues. Objective analysis of intraoperative fluoroscopic images offers an inexpensive, repeatable, and precise assessment strategy without bias. Assessors generally refrain from using the scores of images obtained throughout the operation to evaluate skill for practical reasons. A new system was designed to facilitate rapid analysis of this fluoroscopy via minimally trained analysts. Four expert and four novice analysts independently measured one objective metric for skill using both a custom analysis software and a commercial alternative. Analysts were able to measure the objective metric three times faster when using the custom software, and without a practical difference in accuracy in comparison to the expert analysts using the commercial software. These results suggest that a well-designed fluoroscopy analysis system can facilitate inexpensive, reliable, and objective assessment of surgical skills.