Infectious profiles in civilian gunshot associated long bone fractures.

PURPOSE: There is a paucity of literature on infections in civilian gunshot associated with long bone fractures with the reported rates ranging from 0-15.7%.This study aimed to investigate the rates of infection associated with long bone fractures caused by civilian gunshots. The specific objectives were to determine if certain extremities were at a higher risk for infection and to identify the types of bacteria present in these infections by analyzing culture isolates. METHODS: We conducted a retrospective review of consecutive patients aged 18-64 who sustained gunshot-associated long bone fractures at an urban Level I trauma centre from 2010 to 2017. Patient selection was based done through a institutional trauma centre database using international classification of diseases (ICD) 9 and 10 codes. We included patients who underwent surgical treatment, specifically fracture fixation, at our institution and excluded patients with fractures involving the pelvis, spine, foot, and hand. A total of 384 gunshot-associated long bone fractures in 347 patients were identified for analysis. Relevant patient-, injury-, and treatment-related variables were extracted from clinical records and radiographic reviews. Outcomes of interest included bony union, repeat operative procedures, and the development of deep infection. RESULTS: 347 patients with 384 long bone fractures were included. 32 fractures in 32 patients developed an infection for an incidence of 9.3% of patients and 8.3% of fractures. Gram-positive bacteria were present in 23/32 (72.0%) culture isolates, gram-negative bacteria in 10/32 (31.3%) culture isolates, and six infections were polymicrobial. Staphylococcus 16/32 (50.0%) and Enterobacter 6/32 (18.8%) species were the most common isolates. Of the Staphylococcus species, 5/16 (31.3%) were MRSA. Lower extremity fractures had a greater risk for infection compared to the upper extremity (11.7% vs 3.7% p < 0.01) and fractures that developed an infection had a larger average zone of comminution (63.9 mm vs 48.5 mm p < 0.05). CONCLUSION: This study investigated the rates of infection associated with long bone fractures caused by civilian gunshots. The overall infection rate observed in our series aligns with existing literature. Gram-positive bacteria were the predominant isolates, with a notable incidence of MRSA in our patient population, highlighting the need for considering empiric coverage. Additionally, gram-negative organisms were found in a significant proportion of infections, and a notable percentage of infections were polymicrobial. Our findings emphasize the importance of carefully assessing highly comminuted lower extremity fractures and implementing appropriate antibiotic coverage and operative debridement for patients with gunshot-related long bone fractures. While current prophylaxis algorithms for open fractures lack specific inclusion of gunshot wounds, we propose incorporating these injuries to reduce the incidence of infections associated with such fractures.

A proposed Clino-radio-pathological Risk Scoring System (CRiSS) for prediction and management of inguinal lymph-nodes metastasis in squamous cell carcinoma of the penis.

OBJECTIVE: To develop a risk scoring system for prediction of inguinal lymph-node involvement and to suggest a management strategy according to the risk groups based on clinical, radiological and pathological parameters in squamous cell carcinoma (SCC) of penis. MATERIALS AND METHODS: A retrospective analysis of all patients of SCC penis from 2014 to 2020 at our institute was done. The patients were divided into derivation cohort (2014 to 2019) and validation cohort (2019 to 2020). A total of 10 predictors were analysed in univariate analysis and those found significant were further subjected to multivariate analysis to derive regression coefficient for each. CRiSS scores were assigned based on the coefficients and three groups were created which were correlated with nodal metastasis. The predictive accuracy of the model was assessed by ROC analysis of the derivation cohort and validation cohort. RESULTS: A total of 102 patients were identified in derivation cohort and 23 patients in validation cohort. Size of the primary >3cm, ulceroinfiltrative growth, involving shaft, ultrasound size of lymph-nodes >1cm, loss of fatty hila, moderate and poor differentiation, and lypmphovascular/perineural invasion were independent predictors of inguinal lymphnode metastasis in multivariate analysis. CRiSS could achieve AUROC of .910 and .887 in derivation and validation cohort respectively. The rate of metastatic lymphadenopathy was 0%, 41.4%, and 89.5% in low, intermediate, and high-risk groups respectively. CONCLUSIONS: CRiSS can effectively predict inguinal lymph-node metastasis in SCC penis. We suggest a management strategy based on risk groups that will avoid morbidity of groin dissection in many patients.

Time Trends in Perioperative Characteristics and Health Outcomes in Hispanic Patients Undergoing Primary Total Knee Arthroplasty.

OBJECTIVE: This study analyzed the yearly trends in procedure utilization, comorbidity profiles, hospital length of stay (LOS), and 30-day outcomes in Hispanic/Latino patients undergoing primary total knee arthroplasty (TKA). Risk stratification for the development of postsurgical adverse events (AEs) was also investigated. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) was queried for all Hispanic/Latino patients who underwent primary, elective TKA between 2011 and 2017. Thirty-day outcomes and risk factors were determined using multivariate models that controlled for baseline and perioperative differences. RESULTS: A total of 12,767 Hispanic/Latino patients were identified. Over the study period, the rate of TKA utilization increased by 108%. During the same time, there were significant reductions in the rates of COPD (1.9% vs. 2.9%, p = 0.015), anemia (18.0% vs. 23.5%, p < 0.001), dyspnea (2.9% vs. 4.0%, p = 0.006), and procedure length > 100 min (35.2% vs. 39.4%, p < 0.001). Postoperatively, there was a significant decrease in LOS > 2 days (41.3% vs. 75.6%, p < 0.001), but there was an increase in the rate of developing 30-day AEs (5.8% vs. 4.7%, p = 0.046). Independent risk factors for 30-day AEs included age > 65 years, male sex, chronic steroid use, ASA > 2, diabetes, bleeding disorder, chronic kidney disease, and procedure length > 100 min. CONCLUSION: While the recent trends in procedure utilization, comorbidity profiles, and LOS in Hispanic/Latino patients undergoing primary TKA are reassuring, these have not been accompanied with improved postoperative safety. Patients with bleeding disorders, chronic steroid use, and those admitted from facilities other than home appear to be at highest risk for developing 30-day AEs.

Where Do We Stand Today on Racial and Ethnic Health Inequities? Analysis of Primary Total Knee Arthroplasty from a 2011-2017 National Database.

BACKGROUND: The objective of this study was to present contemporary national data on the state of racial and ethnic disparities pertaining to primary total knee arthroplasty (TKA) in the USA. METHODS: The 2011-2017 National Surgical Quality Improvement Program was used to capture all patients who underwent primary TKA. The study outcomes were differences in demographic, comorbidity burden, perioperative factors, procedure utilization, hospital length of stay (LOS), and 30-day outcomes. The five major minority groups as defined by the National Institutes of Health were compared to non-Hispanic Whites. RESULTS: In total, 262,954 patient records were analyzed, with racial identification available on 230,712 patients (87.7%). White patients accounted for 72.5% of all TKA procedures. There were higher rates of diabetes, hypertension, anemia, and prolonged surgery times among racial and ethnic minorities (p < 0.001). Baseline disparities were especially pronounced among non-Hispanic Blacks/African Americans who were also like to have higher rates of tobacco smoking and CHF (p < 0.001). After controlling for baseline differences, significant disparities in outcomes persisted, especially among Blacks/African Americans and Hispanics/Latinos who had higher odds for experiencing complications and readmissions (p < 0.001). All racial and ethnic groups, except Asians, had longer LOS (p < 0.001). Asian patients had significantly lower rates of readmissions, reoperations, and overall complications (p < 0.001). CONCLUSION: Racial and ethnic disparities remain a public health challenge for patients undergoing TKA. While initiatives aimed at improving preoperative disease-burden and comorbidity profiles represent an important step, they alone are insufficient to fully account for or eliminate the disparities in TKA outcomes.

Endocrine-specific NIR fluorophores for adrenal gland targeting.

The adrenal glands (AGs) are relatively small yet require definitive identification during their resection, or more commonly their avoidance. To enable image-guided surgery involving the AGs, we have developed novel near-infrared (NIR) fluorophores that target the AGs after a single intravenous injection, which provided dual-NIR image-guided resection or avoidance of the AGs during both open and minimally-invasive surgery.

Incidence, Degree, and Clinical Effect of Subchondral Bone Overgrowth After Microfracture in the Knee.

BACKGROUND: Subchondral bone overgrowth has been described with variable frequency after microfracture, but little systematic information is available about the clinical incidence, risk factors, or clinical relevance of this phenomenon. HYPOTHESIS: Subchondral overgrowth (1) occurs with high incidence and various degrees after microfracture, (2) is associated with risk factors, and (3) affects clinical outcome score and failure rate. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 84 patients undergoing microfracture in the knee were prospectively followed up to 6 years postoperatively through use of cartilage-sensitive magnetic resonance imaging to detect the incidence of subchondral bone overgrowth. The quantity of the overgrowth was graded systematically and was then correlated to patient and lesion characteristics, surgical technique, validated functional outcome scores, and failure rate. RESULTS: Subchondral bone overgrowth was observed in 62% of patients at a mean of 22 months after surgery. Most bone overgrowth (64%) was low grade and developed during the first 12 months after microfracture. Risk factors for bone overgrowth included high body mass index, defects on the lateral femoral condyle, and aggressive debridement of the calcified cartilage layer. Knee injury and Osteoarthritis Outcome Score results were not significantly different between patients with or without subchondral bone overgrowth. However, 93% of patients who failed microfracture demonstrated osseous overgrowth, and patients with osseous overgrowth showed a significantly higher failure rate (25%) than patients without overgrowth (3.1%; P < .01). CONCLUSION: Subchondral bone overgrowth is frequently observed after microfracture surgery but is mostly of low grade. Several risk factors were identified that can affect the incidence of this phenomenon. Importantly, subchondral overgrowth is associated with an increased rate of postoperative failure after microfracture.

Intraoperative Hemifacial Composite Flap Perfusion Assessment Using Spatial Frequency Domain Imaging: A Pilot Study in Preparation for Facial Transplantation.

BACKGROUND: Vascularized composite allotransplantation represents an important advancement in the field of reconstructive microsurgery and has continued to increase in popularity. The significant clinical morbidity associated with flap failure represents an important barrier to even more widespread use of these techniques. Early identification of vascular compromise has been associated with a higher salvage rate, yet most surgeons rely only on clinical assessment intraoperatively. Spatial frequency domain imaging (SFDI) presents a noncontact, objective measurement of tissue oxygenation over a large field of view. This study aims to evaluate the use of SFDI technology in hemifacial composite flap compromise as could occur during facial transplant. METHODS: Six composite hemifacial flaps were created in three 35-kg Yorkshire pigs and continuously imaged using SFDI before, during, and after 15-minute selective vascular pedicle occlusion. Arterial and venous clamping trials were performed for each flap. Changes in oxyhemoglobin concentration, deoxyhemoglobin concentration, and total hemoglobin were quantified over time. RESULTS: The SFDI successfully measured changes in oxygenation parameters in all 6 composite tissue flaps. Significant changes in oxyhemoglobin, deoxyhemoglobin, and total hemoglobin were seen relative to controls. Early and distinct patterns of alteration were noted in arterial and in venous compromise relative to one another. CONCLUSIONS: The need for noninvasive, reliable assessment of composite tissue graft viability is apparent, given the morbidity associated with flap failure. The results of this study suggest that SFDI technology shows promise in providing intraoperative guidance with regard to pedicle vessel integrity during reconstructive microsurgery.

Near-infrared imaging for the assessment of anastomotic patency, thrombosis, and reperfusion in microsurgery: a pilot study in a porcine model.

BACKGROUND: Advances in microsurgical techniques have increased the use of free tissue transfer. Methods of intraoperative flap perfusion assessment, however, still rely primarily on subjective evaluation of traditional clinical parameters. Anastomotic thrombosis, if not expeditiously identified and revised, can result in flap loss with significant associated morbidity. This study aims to evaluate the use of near-infrared (NIR) fluorescence imaging in the assessment of microsurgical anastomotic patency, thrombosis, and vascular revision. MATERIALS AND METHODS: A model of pedicle thrombosis was created using bilateral abdominal flaps isolated on deep superior epigastric vascular pedicles in four Yorkshire pigs. Following flap elevation, microvascular arterial and venous anastomoses were performed unilaterally, preserving an intact contralateral control flap. Thrombosis was induced at the arterial anastomosis site using ferric chloride, and both flaps imaged using NIR fluorescence angiography. The thrombosed vascular segments were subsequently excised and new anastomoses performed to restore flow. Follow-up imaging of both flaps was then obtained to confirm patency using fluorescence imaging technology. RESULTS: Pedicled abdominal flaps were created and successful anastomotic thrombosis was induced unilaterally in each pig. Fluorescence imaging technology identified large decreases in tissue perfusion of the thrombosed flap within 2 minutes. After successful revision anastomosis, NIR imaging demonstrated dramatic increase in flow to the reconstructed flap, but intensity did not return to pre-thrombosis levels. CONCLUSIONS: Early identification of anastomotic thrombosis is important in successful free tissue transfer. Real-time, intraoperative evaluation of flap perfusion, anastomotic thrombosis, and successful revision can be performed using NIR fluorescence imaging.

Depth-enhanced fluorescence imaging using masked detection of structured illumination.

There is a growing interest in imaging fluorescence contrast at depth within living tissues over wide fields of view and in real time. Most methods used to date to improve depth detection of fluorescence information involve acquisition of multiple images, postprocessing of the data using a light propagation model, and are capable of providing either depth-sectioned or tomographic fluorescence information. We introduce a method, termed masked detection of structured illumination, that allows the enhancement of fluorescence imaging at depth without postprocessing. This method relies on the scanning of a collimated beam onto a turbid medium and the physical masking of the point spread function on the detection arm before acquisition on a CCD camera. By preferentially collecting diffuse photons at a chosen source-detector range, this method enhances fluorescence information at depth and has the potential to form images without postprocessing and in real time.

Design and characterization of an optimized simultaneous color and near-infrared fluorescence rigid endoscopic imaging system.

We report the design, characterization, and validation of an optimized simultaneous color and near-infrared (NIR) fluorescence rigid endoscopic imaging system for minimally invasive surgery. This system is optimized for illumination and collection of NIR wavelengths allowing the simultaneous acquisition of both color and NIR fluorescence at frame rates higher than 6.8 fps with high sensitivity. The system employs a custom 10-mm diameter rigid endoscope optimized for NIR transmission. A dual-channel light source compatible with the constraints of an endoscope was built and includes a plasma source for white light illumination and NIR laser diodes for fluorescence excitation. A prism-based 2-CCD camera was customized for simultaneous color and NIR detection with a highly efficient filtration scheme for fluorescence imaging of both 700- and 800-nm emission dyes. The performance characterization studies indicate that the endoscope can efficiently detect fluorescence signal from both indocyanine green and methylene blue in dimethyl sulfoxide at the concentrations of 100 to 185 nM depending on the background optical properties. Finally, we performed the validation of this imaging system in vivo during a minimally invasive procedure for thoracic sentinel lymph node mapping in a porcine model.

Near-infrared imaging of face transplants: are both pedicles necessary?

BACKGROUND: Facial transplantation is a complex procedure that corrects severe facial defects due to traumas, burns, and congenital disorders. Although face transplantation has been successfully performed clinically, potential risks include tissue ischemia and necrosis. The vascular supply is typically based on the bilateral neck vessels. As it remains unclear whether perfusion can be based off a single pedicle, this study was designed to assess perfusion patterns of facial transplant allografts using near-infrared (NIR) fluorescence imaging. METHODS: Upper facial composite tissue allotransplants were created using both carotid artery and external jugular vein pedicles in Yorkshire pigs. A flap validation model was created in n = 2 pigs and a clamp occlusion model was performed in n = 3 pigs. In the clamp occlusion models, sequential clamping of the vessels was performed to assess perfusion. Animals were injected with indocyanine green and imaged with NIR fluorescence. Quantitative metrics were assessed based on fluorescence intensity. RESULTS: With NIR imaging, arterial perforators emitted fluorescence indicating perfusion along the surface of the skin. Isolated clamping of one vascular pedicle showed successful perfusion across the midline based on NIR fluorescence imaging. This perfusion extended into the facial allograft within 60 s and perfused the entire contralateral side within 5 min. CONCLUSIONS: Determination of vascular perfusion is important in microsurgical constructs as complications can lead to flap loss. It is still unclear if facial transplants require both pedicles. This initial pilot study using intraoperative NIR fluorescence imaging suggests that facial flap models can be adequately perfused from a single pedicle.

Adaptive wide-field optical tomography.

We describe a wide-field optical tomography technique, which allows the measurement-guided optimization of illumination patterns for enhanced reconstruction performances. The iterative optimization of the excitation pattern aims at reducing the dynamic range in photons transmitted through biological tissue. It increases the number of measurements collected with high photon counts resulting in a dataset with improved tomographic information. Herein, this imaging technique is applied to time-resolved fluorescence molecular tomography for preclinical studies. First, the merit of this approach is tested by in silico studies in a synthetic small animal model for typical illumination patterns. Second, the applicability of this approach in tomographic imaging is validated in vitro using a small animal phantom with two fluorescent capillaries occluded by a highly absorbing inclusion. The simulation study demonstrates an improvement of signal transmitted (∼2 orders of magnitude) through the central portion of the small animal model for all patterns considered. A corresponding improvement in the signal at the emission wavelength by 1.6 orders of magnitude demonstrates the applicability of this technique for fluorescence molecular tomography. The successful discrimination and localization (∼1 mm error) of the two objects with higher resolution using the optimized patterns compared with nonoptimized illumination establishes the improvement in reconstruction performance when using this technique.

Quantitative tomographic imaging of intermolecular FRET in small animals.

Forster resonance energy transfer (FRET) is a nonradiative transfer of energy between two fluorescent molecules (a donor and an acceptor) in nanometer range proximity. FRET imaging methods have been applied to proteomic studies and drug discovery applications based on intermolecular FRET efficiency measurements and stoichiometric measurements of FRET interaction as quantitative parameters of interest. Importantly, FRET provides information about biomolecular interactions at a molecular level, well beyond the diffraction limits of standard microscopy techniques. The application of FRET to small animal imaging will allow biomedical researchers to investigate physiological processes occurring at nanometer range in vivo as well as in situ. In this work a new method for the quantitative reconstruction of FRET measurements in small animals, incorporating a full-field tomographic acquisition system with a Monte Carlo based hierarchical reconstruction scheme, is described and validated in murine models. Our main objective is to estimate the relative concentration of two forms of donor species, i.e., a donor molecule involved in FRETing to an acceptor close by and a nonFRETing donor molecule.

Ex vivo fluorescence molecular tomography of the spine.

We investigated the potential of fluorescence molecular tomography to image ex vivo samples collected from a large animal model, in this case, a dog spine. Wide-field time-gated fluorescence tomography was employed to assess the impact of multiview acquisition, data type, and intrinsic optical properties on the localization and quantification accuracy in imaging a fluorescent inclusion in the intervertebral disk. As expected, the TG data sets, when combining early and late gates, provide significantly better performances than the CW data sets in terms of localization and quantification. Moreover, the use of multiview imaging protocols led to more accurate localization. Additionally, the incorporation of the heterogeneous nature of the tissue in the model to compute the Jacobians led to improved imaging performances. This preliminary imaging study provides a proof of concept of the feasibility of quantitatively imaging complex ex vivo samples nondestructively and with short acquisition times. This work is the first step towards employing optical molecular imaging of the spine to detect and characterize disc degeneration based on targeted fluorescent probes.

Monte Carlo based method for fluorescence tomographic imaging with lifetime multiplexing using time gates.

Time-resolved fluorescence optical tomography allows 3-dimensional localization of multiple fluorophores based on lifetime contrast while providing a unique data set for improved resolution. However, to employ the full fluorescence time measurements, a light propagation model that accurately simulates weakly diffused and multiple scattered photons is required. In this article, we derive a computationally efficient Monte Carlo based method to compute time-gated fluorescence Jacobians for the simultaneous imaging of two fluorophores with lifetime contrast. The Monte Carlo based formulation is validated on a synthetic murine model simulating the uptake in the kidneys of two distinct fluorophores with lifetime contrast. Experimentally, the method is validated using capillaries filled with 2.5nmol of ICG and IRDye™800CW respectively embedded in a diffuse media mimicking the average optical properties of mice. Combining multiple time gates in one inverse problem allows the simultaneous reconstruction of multiple fluorophores with increased resolution and minimal crosstalk using the proposed formulation.

Full-field time-resolved fluorescence tomography of small animals.

In this experimental investigation, we explore the feasibility of using wide-field illumination for time-resolved fluorescence molecular tomography. The performance of wide-field patterns with a time-resolved imaging platform is investigated in vitro and in a small animal model. A Monte Carlo-based forward model is employed to reconstruct fluorescence yield based on time-gated datasets. An improvement in resolution and quantification when using the time-gate data type compared to the commonly used cw data type is demonstrated in vitro. Furthermore, the feasibility of wide-field strategies for fluorescence preclinical applications is established by an accurate localization of a fluorescent inclusion implanted in the chest cavity of a murine model.

Time-resolved diffuse optical tomography with patterned-light illumination and detection.

This investigation explores the feasibility of performing diffuse optical tomography based on time-domain wide-field illumination and detection strategies. Wide-field patterned excitation and detection schemes are investigated in transmittance geometry with time-gated detection channels. A Monte Carlo forward model is employed to compute the time-resolved Jacobians for rigorous light propagation modeling. We demonstrate both in silico and experimentally that reconstructions of absorption structures based on wide-field patterned-light strategies are feasible and outperform classical point excitation schemes for similar data set sizes. Moreover, we demonstrate that time-domain information is retained even though large spatial areas are illuminated. The enhanced time-domain data set allows for quantitative three-dimensional imaging in thick tissue based on relatively small data sets associated with much shorter acquisition times.

Development of an optical imaging platform for functional imaging of small animals using wide-field excitation.

The design and characterization of a time-resolved functional imager using a wide-field excitation scheme for small animal imaging is described. The optimal operation parameters are established based on phantom studies. The performance of the platform for functional imaging and the simultaneous 3D reconstruction of absorption and scattering coefficients is investigated in vitro.