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The Stingray sensor system is a 15-camera optical array dedicated to the nightly astrometric and photometric survey of the geosynchronous Earth orbit (GEO) belt visible above Tucson, Arizona. The primary scientific goal is to characterize GEO and near-GEO satellites based on their observable properties. This system is completely autonomous in both data acquisition and processing, with human oversight reserved for data quality assurance and system maintenance. The 15 ZWO ASI1600MM Pro cameras are mated to Sigma 135 mm f/1.8 lenses and are controlled simultaneously by four separate computers. Each camera is fixed in position and observes a 7.6-by-5.8-degree portion of the GEO belt, for a total of a 114-by-5.8-degree field of regard. The GAIA DR2 star catalog is used for image astrometric plate solution and photometric calibration to GAIA G magnitudes. There are approximately 200 near-GEO satellites on any given night that fall within the Stingray field of regard, and all those with a GAIA G magnitude brighter than approximately 15.5 are measured by the automated data reduction pipeline. Results from an initial one-month survey show an aggregate photometric uncertainty of 0.062 ± 0.008 magnitudes and astrometric accuracy consistent with theoretical sub-pixel centroid limits. Provided in this work is a discussion of the design and function of the system, along with verification of the initial survey results.
RESUMEN
BACKGROUND: Lisfranc injuries refer to a disruption or displacement of the tarsometatarsal joint of the foot. Subtle Lisfranc injuries can go undiagnosed on conventional imaging leading to devastating consequences and poor functional outcomes for elite athletes. Objective. The objective of this case study is to present a novel imaging technique using weight-bearing computed tomography (CT) with enhanced stress to identify subtle, dynamically unstable Lisfranc injuries. We illustrate this with a case presentation of an elite athlete who ultimately required surgical fixation for a subtle Lisfranc injury. MATERIALS AND METHODS: To perform an augmented stress weight-bearing CT, the patient was positioned standing, with their feet facing forward, and weight equally distributed. The patient was then coached to symmetrically raise both heels from the scanner platform. This plantarflexion provided augmented stress on the midfoot, allowing for more sensitive imaging of the Lisfranc injury. The weight-bearing CT and augmented stress images undergo 3D reconstruction and postprocessing to render coronal and sagittal images, allowing for comparison of the standard weight-bearing and augmented stress images. RESULTS: We present the case of a 22-year-old collegiate football lineman sustaining a Lisfranc injury. The injury diagnosis was made by magnetic resonance imaging (MRI) and clinical examination, without evidence of injury on weight-bearing XR or standard weight-bearing CT. With augmented stress CT imaging, the Lisfranc instability was noted, leading to surgical fixation, and return to sport the next season. CONCLUSION: We propose this technique for diagnosing subtle, unstable Lisfranc injuries where clinical suspicion persists despite inconclusive imaging, particularly in elite athletes. Further research is needed with larger sample sizes to investigate the sensitivity of this novel imaging technique for the detection of Lisfranc injury. LEVELS OF EVIDENCE: Level 4: Case Report.
RESUMEN
BACKGROUND: The purpose of this study was to externally validate a predictive score for fracture-related infections, establishing generalizability for absolute and relative risk of infection in the setting of orthopedic fracture surgery. MATERIALS AND METHODS: This was a retrospective, case-control study performed at a level I academic trauma center that included 147 patients with fracture-related infection in the study group and 300 control patients. We analyzed the same 8 independent predictors of fracture-related infection cited by a previous study. We then used the area under the receiver operating characteristics curve (AUC) to compare the derivation and validation cohorts. The validation and derivation cohorts were then compared by grouping patients into 4 strata of Wise score groups. This allowed for comparison of AUC and risk of fracture-related infection in our institution with those in the previously studied institution. RESULTS: The resulting data yielded an AUC (0.74) nearly identical to that of the previously studied institution. It was also found that the relative risk of infection correlated with the Wise score in the same way the initial model did with the absolute risks being similar. CONCLUSION: The previous predictive model was externally validated and shown to be generalizable to a different patient population. The relative risk of a fracture-related infection can be determined using this scoring model preoperatively with the goal of aiding in patient counseling and surgical decision-making, giving a quantitative value to patient risk factors. [Orthopedics. 202x;4x(x):xx-xx.].