Incidence of Intraoperative Cardiothoracic Intervention During Open Surgery Following Acute Posterior Sternoclavicular Joint Injury: A Case Series and Review of the Literature.

BACKGROUND: Acute posterior sternoclavicular joint injuries are rare but potentially lethal injuries-signs of mediastinal compression range from nonspecific to neurovascular compromise. Currently, orthopaedic experts recommend a cardiothoracic surgeon be placed on standby during open surgery for potential intraoperative complications. However, few studies have reported on how often cardiothoracic intervention is required. METHODS: First, we identified patients in our institution by CPT codes 23530, 23525, and 23532 from January 1, 2002 to May 1, 2023. Demographic variables and intraoperative cardiothoracic intervention rates were collected. Second, we systematically reviewed the literature to identify articles on acute posterior sternoclavicular injury using PubMed, Embase, and CINAHL databases (through August 20, 2023). Exclusion criteria included conservative treatment, successful closed reduction, chronic injury (>6 wk) cadaver studies, reviews, and nonavailable text. RESULTS: Thirteen local patients underwent open surgery for an acute posterior sternoclavicular joint injury, 11 males and 2 females with an average age of 18.2 years old (range: 15 to 32.4). The most common mechanism of injury was sports (n=9; 69.2%). Four (30.8%) patients had physical or radiographic evidence of mediastinal compression. No patients required intraoperative cardiothoracic intervention in our institution. The literature search yielded 132 articles and 512 open surgeries for acute posterior sternoclavicular joint injuries. Four patients required intraoperative cardiothoracic intervention, all of whom presented with polytrauma and/or clinical or radiographic signs of neurovascular compromise, giving a combined overall rate of 0.76%. CONCLUSIONS: Expert opinion commonly recommends cardiothoracic backup during open surgery for acute posterior sternoclavicular joint injuries. On the basis of our local data and systematic literature review, we found an overall cardiothoracic intervention rate of 0.76%. In the presence of polytrauma and/or findings of neurovascular compromise, we suggest having cardiothoracic surgery on close standby during the procedure. However, a patient with an isolated acute posterior sternoclavicular joint injury and no clinical or radiographic findings of neurovascular compromise does not appear to require a cardiothoracic surgeon on standby. Ultimately, the decision to involve cardiothoracic backup during open surgery for an acute posterior sternoclavicular injury should be made on a case-by-case basis after a thorough physical and radiographic evaluation of the patient. LEVEL OF EVIDENCE: Level III.

Polarization properties and Umov effect of human hair.

This study delves into the polarization properties of various hair colors using several techniques, including polarization ray tracing, full Stokes, and Mueller matrix imaging. Our analysis involved studying hair in both indoor and outdoor settings under varying lighting conditions. Our results demonstrate a strong correlation between hair color and the degree of linear polarization. Specifically, light-colored hair, such as white and blond, exhibits high albedo and low DoLP. In contrast, dark hair, like black and brown hair, has low albedo and high DoLP. Our research also revealed that a single hair strand displays high diattenuation near specular reflections but high depolarization in areas with diffuse reflections. Additionally, we investigated the wavelength dependency of the polarization properties by comparing the Mueller matrix under illumination at 450 nm and 589 nm. Our investigation demonstrates the impact of hair shade and color on polarization properties and the Umov effect.

Birefringent coating to remove polarization aberrations.

Polarization aberrations are found in most optical components due to a materials-differing response to s- and p-polarizations. This differing response can manifest either as diattenuation, retardance, or both. Correction of polarization aberrations, such as these, are critical in many applications such as interferometry, polarimetry, display, and high contrast imaging, including astronomy. In this work, compensators based on liquid crystal polymer and anti-reflection thin-films are presented to correct polarization aberrations in both transmission and reflection configurations. Our method is versatile, allowing for good correction in transmission and reflection due to optical components possessing differing diattenuation and retardance dispersions. Through simulation and experimental validation we show two designs, one correcting the polarization aberrations of a dichroic spectral filter over a 170nm wavelength band, and the other correcting the polarization aberration of an aluminum-coated mirror over a 400nm wavelength band and a 55-degree cone of angles. The measured performance of the polarization aberration compensators shows good agreement with theory.

Generalized elliptical retarder design and construction using nematic and cholesteric phase liquid crystal polymers.

Elliptical retarders have important applications in interferometry and polarimetry, as well as imaging and display technologies. In this work, we discuss the traditional elliptical retarder decomposition using Pauli matrices as basis sets and then introduce a solution to the inverse problem: how an arbitrary elliptical retarder with desired eigenpolarizations and retardance can be constructed using a combination of linear and circular retarders. We present a simple design process, based on eigen-decomposition, with a solution determined by the intrinsic properties of each individual retarder layer. Additionally, a novel use of cholesteric liquid crystal polymer as a circular retarder is presented. Through simulation and experimental validation, we show cholesteric phase liquid crystal has an achromatic region of circular retardance at shorter wavelengths, outside of the Bragg regime. Finally, we verify our design process by fabricating and testing an elliptical retarder using both nematic and cholesteric phase liquid crystal polymers. The performance of the elliptical retarders shows excellent agreement with theory.

Patterned achromatic elliptical polarizer for short-wave infrared imaging polarimetry.

Short-wave infrared (SWIR) imaging polarimetry has widespread applications in telecommunication, medical imaging, surveillance, remote-sensing, and industrial metrology. In this work, we design, fabricate, and test an achromatic SWIR elliptical polarizer, which is a key component of SWIR imaging polarimetry. The elliptical polarizer is made of a patterned linear polarizer and a patterned optical elliptical retarder. The linear polarizer is a wire grid polarizer. The elliptical retarder is constructed with three layers of nematic phase A-plate liquid crystal polymer (LCP) films with different fast axis orientations and physical film thicknesses. For each LCP layer, four arrays of hexagonal patterns with individual fast-axis orientations are realized utilizing selective linearly polarized ultraviolet (UV) irradiation on a photo-alignment polymer film. The Mueller matrices of the optical filters were measured in the wavelength range 1000 nm to 1600 nm and compared with theory. Our results demonstrate the functionality and quality of the patterned retarders with normalized analyzer vector parameter deviation below 7% over this wavelength range. To the best of our knowledge, this work represents the first polymer-based patterned elliptical polarizer for SWIR polarimetry imaging applications.

Patterned liquid crystal polymer C-plate retarder and color polarizer.

The patternability and guest-host interaction with dichroic dye and C-plate liquid crystal polymer (LCP) materials are investigated, and the optical properties of a thin film C-plate retarder and polarizer are studied and compared with theory. The C-plate retarder is a waveplate made of a uniaxial LCP where the optical axis of the LCP is parallel to the surface normal of the optic. No retardance is observed at a normal angle of incidence and retardance grows as the angle of incidence increases. The C-plate polarizer is a C-plate retarder with LCP as the host and a dichroic dye as the guest. The linear diattenuation (LD) of the linear polarizer is zero at a normal angle of incidence and grows with an increasing angle of incidence. Both the C-plate retarder and polarizer can be patterned with minimum feature size down to 2 µm by using ultraviolet photolithography and plasma etching. A planarization process is also developed to deposit a cover layer on top of the pattern to reduce optical loss and to serve as a barrier for subsequent layers.

Division of focal plane red-green-blue full-Stokes imaging polarimeter.

We calibrate and test a division-of-focal-plane red-green-blue (RGB) full-Stokes imaging polarimeter in a variety of indoor and outdoor environments. The polarimeter, acting as a polarization camera, utilizes a low dispersion microretarder array on top of a sensor with Bayer filters and wire-grid linear polarizers. We also present the design and fabrication of the microretarder array and the assembly of the camera and validate the performance of the camera by taking multiple RGB full-Stokes images and videos. Our camera has a small form factor due to its single-sensor design and the unique capability to measure the intensity, color, and polarization of an optical field in a single shot.

Observation of elliptically polarized light from total internal reflection in bubbles.

Bubbles are ubiquitous in the natural environment, where different substances and phases of the same substance forms globules due to differences in pressure and surface tension. Total internal reflection occurs at the interface of a bubble, where light travels from the higher refractive index material outside a bubble to the lower index material inside a bubble at appropriate angles of incidence, which can lead to a phase shift in the reflected light. Linearly polarized skylight can be converted to elliptically polarized light with efficiency up to 53% by single scattering from the water-air interface. Total internal reflection from air bubble in water is one of the few sources of elliptical polarization in the natural world. Stationary and dynamic scenes of air bubbles in water in both indoor and outdoor settings are studied using an imaging polarimeter. Our results are important for studies in fluid dynamics, remote sensing, and polarimetry.

Polarizing beam splitter cube for circularly and elliptically polarized light.

A method of designing an arbitrary polarizing beam splitter (PBS) cube using multiple layers of thin-film liquid crystal polymer is demonstrated. This methodology utilizes cholesteric phase liquid crystal polymer (Ch-LCP) to transmit one handedness of elliptically polarized light and reflect the orthogonal state when unpolarized light is incident. Using additional nematic liquid crystal polymer layers, the polarization state for the transmitted and reflected light can be controlled and output to any two orthogonal states represented on the Poincaré sphere. Two cubes are designed, fabricated, tested, and compared with theory. One cube is constructed with a single layer of Ch-LCP, and another cube is constructed with a layer of Ch-LCP and an additional nematic liquid crystal polymer layer.