Fundamental analysis of liquid breakup mechanism in a rotary atomizer with square discharge orifice

[EN] An experimental investigation of breakup mechanism in a rotary atomizer with square shape discharge orifice at ambient condition has been performed. The effects of a high aspect ratio noncircular discharge channels, particularly a square shape discharge channel, are considered. The motivation of this study is the use of this type of orifice in some small gas turbine engines as well as non-existing observation in literature concerning about high aspect ratio of discharge channel. Visualization experiments are conducted by high speed shadowgraph imaging technique with pulsed light illumination for the first time. The effects of rotational speed and volume flow rate are studied on the breakup structure. The visualizations indicates that the liquid film formed along the channel is pushed to one side of it due to Coriolis force which is dominant in this type of atomizer. Accordingly a crescent shaped liquid film is formed at the square channel exit covering two corners of the square, resulting the combination of Coriolis induced stream mode and surface tension induced stream mode breakup. Observations of the breakup process for different volume flow rates and rotational speeds indicate that the breakup of liquid film stream is dependent on injection conditions and the corresponding cross flow velocity created by atomizer rotation. The breakup regime map is provided as a function of weber number and momentum flux ratio. Four distinct regimes are identified: Rayleigh breakup, bag breakup, multimode breakup, and shear breakup. The present results leads to understanding atomization performance and creating some idea to improved spray quality in this type of atomizer.Ghorbanhoseini, M.; Rezayat, S.; Farshchi, M. (2017). Fundamental analysis of liquid breakup mechanism in a rotary atomizer with square discharge orifice. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 496-503. https://doi.org/10.4995/ILASS2017.2017.5640OCS49650

Racial disparities in access to pain management services during COVID pandemic at an urban safety-net hospital

Background: Race has been identified as one of the great divisions of mankind, associated with differences in healthcare access in the US. The COVID pandemic has shed light on a variety of disparities, including access to pain management services. Method: All the adult patients who were referred to the pain clinic at Boston Medical Center (BMC) from December 2019- December 2020 were included in this study. A total of 2023 cases (1243 White Race and 790 People of Color) were recruited. Result: Patients of WR received care at a younger age. COVID-19 increased the average age of WR by 2.5 years, while it didn’t affect POC. The average gap between the date of the consult and the procedure was not significantly different between the 2 groups. It also was not significantly different pre-COVID and post-COVID. There were no differences in the racial makeup of the referred patients before and after the pandemic, although the percentage of patients being POC (39.3%) was significantly lower than the racial makeup of the representing population (47.18%). Patients of WR were significantly more likely to have completed visits (66.3%) than POC (60.5%). Conclusion: Our study demonstrated disparities between the WR and POC that were evident even before starting the COVID-19 pandemic. It also showed that these disparities continued to be the same as before COVID-19. Although many disparities are rooted in the society itself, we noticed that in numerous instances, pain management services were offered equally at our institution. We suggest that multiracial administrative staff living in the same community and hospital-sponsored support systems were the main contributors

The effect of gentamycin in the irrigating solution to prevent joint infection after anterior cruciate ligament (ACL) reconstruction

Background: Arthroscopic reconstruction of ACL is an effective method to restore knee stability after ACL rupture. Postoperative septic arthritis (SA) is very uncommon while the incidence of serious complications range between 0.14 and 1.8. Some of the devastating consequences of septic arthritis can encompass hyaline cartilage damage, arthrofibrosis, and in rare cases amputation. The purpose of this study was to evaluate the effect of gentamicin irrigation solutions as a process to restrain septic arthritis following arthroscopic ACL reconstruction. Methods: In this retrospective cohort study, 1464 patients who underwent ACL reconstruction with hamstring tendon autograft in our institution over 7 years (February 2008 to January 2015) were included. The patients were divided into two groups based on the type of intra-articular irrigation solution used during the surgery. Patients in Group 1 (Saline) received intra-articular irrigation with normal saline (0.9 sodium chloride) solution, while those in Group 2 (Gentamycin) received intra-articular irrigation with gentamicin (80 mg/L) added to the normal saline solution. Data about postoperative infection, its course, management, and outcome were obtained from patients' records. Results: Seven patients developed SA, four of whom were from SALINE group (2.2) and three from Gentamycin group (0.23). The incidence rate of SA after arthroscopic ACL reconstruction was significantly lower (P <0.05) when irrigated with gentamicin solution than merely with saline solution. Conclusion: Gentamicin irrigation solution has a preservative and protective effect against SA development following arthroscopic ACL reconstruction. We recommend evaluating this technique as a way in order to depreciate the prevalence of SA after ACL reconstruction. © 2019 BY THE ARCHIVES OF BONE AND JOINT SURGERY

Short term results of anterior cruciate ligament augmentation in professional and amateur athletes

Background: Anterior cruciate ligament (ACL) reconstruction is a widely accepted procedure; however, controversies exist about ACL augmentation. The purpose of this study was to assess the clinical outcomes of ACL augmentation in professional and amateur athletes with isolated single bundle ACL tears. Materials and methods A consecutive series of professional and amateur athletes with partial ACL tears who underwent selective bundle reconstruction were analyzed. Stability was assessed with the Lachman test, anterior-drawer test, pivot-shift test and KT-1000 arthrometer. Functional assessment was performed using the subjective Lysholm questionnaire. Results: Fifty-six patients were enrolled. The mean follow-up period was 19.3 months. All patients had posterolateral bundle (PLB) tears, and no anteromedial bundle (AMB) tears were found. The Lysholm score improved significantly from 78 (SD = 2.69) preoperatively to 96 (SD = 3.41) postoperatively (P value <0.0001). The pivot-shift test, Lachman test and anterior-drawer test results were negative in all cases postoperatively. Anterior tibial translation from neutral was 4.9 mm (SD = 2.7) preoperatively, and decreased significantly to 2.1 (SD = 0.6) postoperatively, measured with a KT-1000 arthrometer (P value <0.00001). Conclusion: In this study, we showed that ACL augmentation had good results in symptomatic professional and amateur athletes, and although further studies are needed to investigate long-term results, we recommend this surgery for all symptomatic athletic patients, especially those who would like to maintain an active lifestyle. Level of evidence IV

Does a Patient’s Self-Reported Ability to Weightbear Immediately after Injury Predict Stability for Ankle Fractures

Category: Trauma Introduction/Purpose: Determining the stability of ankle fractures, particularly for apparent isolated Weber B fibula fractures, can be difficult. While the ultimate goal remains achieving an anatomic mortise, different techniques to predict ankle stability such as stress and weightbearing radiographs have been utilized with variable results. History of injury and the ability to walk after sustaining ankle trauma may be predictive of stability. Therefore, this study seeks to determine whether a patient’s ability to fully weight bear immediately after injury is an effective indicator for ankle stability following ankle fracture. Methods: A prospective review was conducted of patients sustaining isolated, unilateral ankle fractures presenting to two level I trauma centers. Aside from demographic data and fracture characteristics, a patient’s ability or inability to fully weightbear immediately after injury was elicited by interview at their initial assessment. This information was correlated with their ankle radiographs, which were deemed stable or unstable fractures based on commonly used indices to assess ankle stability. Results: 102 consecutive patients sustaining ankle fractures were included. Mean age was 45. When analyzing the entire cohort, patients who were able to ambulate immediately after injury were 10 times more likely to have a stable ankle fracture than those who could not bear weight (odds ratio (OR) 9.9 (P < 0.001). The positive predictive value (PPV) for being able to fully weightbear as it relates to a stable ankle fracture was 77%. Additionally, inability to weightbear was 89% specific for an unstable fracture. When separately analyzing patients with apparent isolated fibula fractures (n=56), the PPV was 75%, specificity was 83%, while the OR was 5.8 (p=0.003) for those who could fully bear weight having a stable ankle fracture. Conclusion: This study demonstrates that patient’s self-reported ability to fully weightbear immediately after injury is a specific and convenient prognostic indicator for ankle stability across a range of ankle fracture subtypes. Future studies can analyze whether initial weightbearing accurately predicts ultimate management and good outcome

Consideration of Medial Anatomical Structures at Risk when Placing Quadricortical Syndesmotic Fixation

Category: Trauma Introduction/Purpose: Surgical fixation of ankle fractures with syndesmotic instability using quadricortical fixation through the fibula and tibia is commonly performed to maintain mortise congruency. Quadricortical fixation can be achieved by screws or suture buttons however both involve unprotected drilling and placement of hardware through the medial distal tibia which places anatomic structures at iatrogenic risk. These structures may include the anterior tibialis tendon, the saphenous neurovascular bundle (SNVB) and posteriorly, the posterior tibialis tendon (PTT). This study aims to radiographically map the anatomic course of these structures at risk on a lateral radiograph as would be used intraoperatively during syndesmotic fixation. Methods: Eighteen fresh-frozen cadaveric feet were dissected with preservation of all soft tissue and neurovascular structures over the medial distal tibia. While preserving fascial and tendinous sheath attachments, the SNVB and the PTT were identified and marked with metal wiring. Standardized and calibrated lateral radiographs were obtained to determine the anatomic course of these structures. Lateral radiographs of the distal tibia and fibula were analyzed by a grid system comprised of 1 cm row-increments moving cranially from the ankle joint up to 5 cm and by 3 evenly distributed parallel columnar zones from anterior to posterior (see Figure). The anterior boundary of the columnar zone was placed at the anterior tibial shaft and the posterior boundary was placed at the posterior malleolus of the tibia. The position of respective metal wires placed within the SNVB and the anterior portion of the PTT were charted according to this grid system and results compiled. Results: The SNVB was located in zone 1 or 2 (or anterior to zone 1) in 97.3% of specimens (107/110). The SNVB traversed from proximal-posterior to distal-anterior. For the 16 specimens that crossed a columnar zone, the most common crossover was from zone 2 to zone 1 at 3-4 cm above the ankle joint which occurred in 43.8% (7 of 16) specimens. The PPT was found in zone 3 in all specimens (n=18) with only one specimen demonstrating crossover of a columnar zone into zone 2 at its most distal extent (0-1 cm). The PTT was noted to pass behind (radiographically overlap) with the tibia in 83.3% (15 of 18) of specimens between 1 and 3 cm above the ankle joint. Conclusion: Inappropriate placement of quadricortical syndesmotic fixation may place structures on the medial ankle at risk given blind drilling and hardware placement. The SNVB is at considerable risk along the anterior course of the distal tibial while the PTT is only at risk in zone 3 at the distal extent of the tibia when a true lateral radiograph is obtained. This grid system allows a simple intra-operative check to guide safer placement of quadricortical syndesmotic fixation

High Variability of Observed Weight Bearing During Standing Foot and Ankle Radiographs

Category: Basic Sciences/Biologics, Trauma Introduction/Purpose: Weight bearing radiographs are a critical component of evaluating foot and ankle pathology. An underlying assumption is that patients are placing 50% of their body weight on the affected foot during image acquisition. The accuracy of weight bearing during radiographs is unknown and, presumably, variable, which may result in uncertain ability of the resultant radiographs to accurately portray the pathology of interest. Methods: 50 subjects were tested. The percent body weight through the foot of interest was measured at the moment of radiographic image acquisition. The subject was then instructed to “bear ½ body weight” prior to the next radiograph. The percent body weight was calculated and compared to ideal 50% weight bearing. Results: The mean percent body weight in trial 1 and 2 was 45.7% ± 3.2% (p=0.012 compared to 50% mark) and 49.2% ± 2.4%, respectively (p=0.428 compared to 50%). The mean absolute difference in percent weight bearing compared to 50% in trials 1 and 2 was 9.3% ± 2.25% and 5.75% ± 1.8%, respectively (p=0.005). For trial 1, 18/50 subjects were within the “ideal” (45-55%) range for weight bearing compared to 32/50 on trial 2 (p=0.005). In trial 1 24/50 subjects had “appropriate” (>45%) weight bearing compared to 39/50 on trial 2 (p=0.002). Conclusion: There is substantial variability in the weight applied during radiograph acquisition. This study raises significant questions about assumptions we, as orthopaedic surgeons, have made regarding weight bearing radiographs, their reliability and how we should proceed when evaluating them