Heavy-element production in a compact object merger observed by JWST.

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GWs)2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers4-6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7-12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe.

A rotating white dwarf shows different compositions on its opposite faces.

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen or helium1,2. Several mechanisms compete with gravitational settling to change a white dwarf's surface composition as it cools3, and the fraction of white dwarfs with helium atmospheres is known to increase by a factor of about 2.5 below a temperature of about 30,000 kelvin4-8; therefore, some white dwarfs that appear to have hydrogen-dominated atmospheres above 30,000 kelvin are bound to transition to be helium-dominated as they cool below it. Here we report observations of ZTF J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface9-11. ZTF J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs-together with GD 323 (ref. 12), a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.

3D observations provide striking findings in rubber elasticity.

The mechanical response of rubbers has been ubiquitously assumed to be only a function of the imposed strain. Using innovative X-ray measurements capturing the three-dimensional spatial volumetric strain fields, we demonstrate that rubbers and indeed many common engineering polymers undergo significant local volume changes. But remarkably, the overall specimen volume remains constant regardless of the imposed loading. This strange behavior which also leads to apparent negative local bulk moduli is due to the presence of a mobile phase within these materials. Combining X-ray tomographic observations with high-speed radiography to track the motion of the mobile phase, we have revised classical thermodynamic frameworks of rubber elasticity. The work opens broad avenues to understand not only the mechanical behavior of rubbers but a large class of widely used engineering polymers.

Cytomegalovirus Infection Facilitates the Costimulation of CD57+CD28- CD8 T Cells in HIV Infection and Atherosclerosis via the CD2-LFA-3 Axis.

CD8 T cells are emerging as important mediators in atherosclerosis and cardiovascular disease (CVD). Immune activation may play a particular role in people with HIV (PWH) who are at an increased risk of CVD, even after controlling for known CVD risk factors. Latent CMV infection is associated with increased CVD risk for both PWH and people without HIV, and human CMV-specific CD4 and CD8 T cells are enriched for an immunosenescent phenotype. We previously showed that CMV coinfection in PWH promotes vascular homing and activation of inflammatory CD4 T cells through the CD2-LFA-3 axis. However, the role of CD2/LFA3 costimulation of CD8 T cells in PWH with CMV has yet to be described. In the present study, we demonstrate that CD2 expression on CX3CR1+CD57+CD28- inflammescent CD8 T cells is increased on cells from CMV-seropositive PWH. In vitro CD2/LFA-3 costimulation enhances TCR-mediated activation of these inflammatory CD8 memory T cells. Finally, we show that LFA-3 is highly expressed in aortas of SIV-infected rhesus macaques and in atherosclerotic plaques of people without HIV. Our findings are consistent with a model in which CMV infection enhances CD2 expression on highly proinflammatory CD8 T cells that can then be stimulated by LFA-3 expressed in the vasculature, even in the absence of CD28 costimulation. This model, in which CMV infection exacerbates toxic cytokine and granzyme production by CD8 T cells within the vasculature, highlights a potential therapeutic target in atherosclerosis development and progression, especially for PWH.

Underexcitation prevents crystallization of granular assemblies subjected to high-frequency vibration.

Crystallization of dry particle assemblies via imposed vibrations is a scalable route to assemble micro/macro crystals. It is well understood that there exists an optimal frequency to maximize crystallization with broad acceptance that this optimal frequency emerges because high-frequency vibration results in overexcitation of the assembly. Using measurements that include interrupted X-ray computed tomography and high-speed photography combined with discrete-element simulations we show that, rather counterintuitively, high-frequency vibration underexcites the assembly. The large accelerations imposed by high-frequency vibrations create a fluidized boundary layer that prevents momentum transfer into the bulk of the granular assembly. This results in particle underexcitation which inhibits the rearrangements required for crystallization. This clear understanding of the mechanisms has allowed the development of a simple concept to inhibit fluidization which thereby allows crystallization under high-frequency vibrations.

Sigmoni: classification of nanopore signal with a compressed pangenome index.

SUMMARY: Improvements in nanopore sequencing necessitate efficient classification methods, including pre-filtering and adaptive sampling algorithms that enrich for reads of interest. Signal-based approaches circumvent the computational bottleneck of basecalling. But past methods for signal-based classification do not scale efficiently to large, repetitive references like pangenomes, limiting their utility to partial references or individual genomes. We introduce Sigmoni: a rapid, multiclass classification method based on the r-index that scales to references of hundreds of Gbps. Sigmoni quantizes nanopore signal into a discrete alphabet of picoamp ranges. It performs rapid, approximate matching using matching statistics, classifying reads based on distributions of picoamp matching statistics and co-linearity statistics, all in linear query time without the need for seed-chain-extend. Sigmoni is 10-100× faster than previous methods for adaptive sampling in host depletion experiments with improved accuracy, and can query reads against large microbial or human pangenomes. Sigmoni is the first signal-based tool to scale to a complete human genome and pangenome while remaining fast enough for adaptive sampling applications. AVAILABILITY AND IMPLEMENTATION: Sigmoni is implemented in Python, and is available open-source at https://github.com/vshiv18/sigmoni.

Cerebellar Excitability Regulates Physical Fatigue Perception.

Fatigue is the subjective sensation of weariness, increased sense of effort, or exhaustion and is pervasive in neurologic illnesses. Despite its prevalence, we have a limited understanding of the neurophysiological mechanisms underlying fatigue. The cerebellum, known for its role in motor control and learning, is also involved in perceptual processes. However, the role of the cerebellum in fatigue remains largely unexplored. We performed two experiments to examine whether cerebellar excitability is affected after a fatiguing task and its association with fatigue. Using a crossover design, we assessed cerebellar inhibition (CBI) and perception of fatigue in humans before and after "fatigue" and "control" tasks. Thirty-three participants (16 males, 17 females) performed five isometric pinch trials with their thumb and index finger at 80% maximum voluntary capacity (MVC) until failure (force <40% MVC; fatigue) or at 5% MVC for 30 s (control). We found that reduced CBI after the fatigue task correlated with a milder perception of fatigue. In a follow-up experiment, we investigated the behavioral consequences of reduced CBI after fatigue. We measured CBI, perception of fatigue, and performance during a ballistic goal-directed task before and after the same fatigue and control tasks. We replicated the observation that reduced CBI after the fatigue task correlated with a milder perception of fatigue and found that greater endpoint variability after the fatigue task correlated with reduced CBI. The proportional relation between cerebellar excitability and fatigue indicates a role of the cerebellum in the perception of fatigue, which might come at the expense of motor control.SIGNIFICANCE STATEMENT Fatigue is one of the most common and debilitating symptoms in neurologic, neuropsychiatric, and chronic illnesses. Despite its epidemiological importance, there is a limited understanding of the neurophysiological mechanisms underlying fatigue. In a series of experiments, we demonstrate that decreased cerebellar excitability relates to lesser physical fatigue perception and worse motor control. These results showcase the role of the cerebellum in fatigue regulation and suggest that fatigue- and performance-related processes might compete for cerebellar resources.

Female and male patients have similar outcomes after transcarotid artery revascularization in prospective trials.

OBJECTIVE: Sex disparities in outcomes after carotid revascularization have long been a concern, with several studies demonstrating increased postoperative death and stroke for female patients after either carotid endarterectomy or transfemoral stenting. Adverse events after transfemoral stenting are higher in female patients, particularly in symptomatic cases. Our objective was to investigate outcomes after transcarotid artery revascularization (TCAR) stratified by patient sex hypothesizing that the results would be similar between males and females. METHODS: We analyzed prospectively collected data from the Safety and Efficacy Study for Reverse Flow Used During Carotid Artery Stenting Procedure (ROADSTER)1 (pivotal), ROADSTER2 (US Food and Drug Administration indicated postmarket), and ROADSTER Extended Access TCAR trials. All patients had verified carotid stenosis meeting criteria for intervention (≥80% for asymptomatic patients and ≥50% in patient with symptomatic disease), and were included based on anatomical or clinical high-risk criteria for carotid stenting. Neurological assessments (National Institutes of Health Stroke Scale, Modified Rankin Scale) were obtained before and within 24 hours from procedure end by an independent neurologist or National Institutes of Health Stroke Scale-certified nurse. Patients were stratified by sex (male vs female). Baseline demographics were compared using χ2 and Fisher's exact tests where appropriate; primary outcomes were combination stroke/death (S/D) and S/D/myocardial infarction (S/D/M) at 30 days, and secondary outcomes were the individual components of S/D/M. Univariate logistic regression was conducted. RESULTS: We included 910 patients for analysis (306 female [33.6%], 604 male [66.4%]). Female patients were more often <65 years old (20.6% vs 15%) or ≥80 years old (22.6% vs 20.2%) compared with males, and were more often of Black/African American ethnicity (7.5% vs 4.3%). There were no differences by sex in term of comorbidities, current or prior smoking status, prior stroke, symptomatic status, or prevalence of anatomical and/or clinical high-risk criteria. General anesthetic use, stent brands used, and procedure times did not differ by sex, although flow reversal times were longer in female patients (10.9 minutes male vs 12.4 minutes female; P = .01), as was more contrast used in procedures for female patients (43 mL male vs 48.9 mL female; P = .049). The 30-day S/D and S/D/M rates were similar between male and female patients (S/D, 2.7% male vs 1.6% female [P = .34]; S/D/M, 3.6% male vs 2.6% female [P = .41]), which did not differ when stratified by symptom status. Secondary outcomes did not differ by sex, including stroke rates at 30 days (2.2% male vs 1.6% female; P = .80), nor were differences seen with stratification by symptom status. Univariate analysis demonstrated that history of a prior ipsilateral stroke was associated with increased odds of S/D (odds ratio [OR], 4.19; P = .001) and S/D/M (OR, 2.78; P = .01), as was symptomatic presentation with increased odds for S/D (OR, 2.78; P = .02). CONCLUSIONS: Prospective TCAR trial data demonstrate exceptionally low rates of S/D/MI, which do not differ by patient sex.

Direct oral anticoagulants over warfarin at discharge associated with improved survival and patency in infra-geniculate bypasses with prosthetic conduits.

OBJECTIVE: There is no consensus on the optimal anticoagulant regimen following lower extremity bypass. Historically, warfarin has been utilized for prosthetic or compromised vein bypasses. Direct-acting oral anticoagulants (DOACs) are increasingly replacing warfarin in this context, but their efficacy in bypass preservation has not been well-studied. Recent studies have shown that DOACs may improve outcomes following bypasses; however, it is unclear if this is dependent upon type of bypass conduit. The goal of this study was to evaluate whether a difference exists between vein and prosthetic infra-geniculate bypasses outcomes based on the anticoagulant utilized on discharge, warfarin or DOAC. METHODS: The Vascular Quality Initiative infra-inguinal bypass database was queried for all patients who underwent an infra-geniculate bypass and were anticoagulation-naive at baseline but were discharged on either warfarin or DOACs. A survival analysis was performed for patients up to 1 year to determine whether the choice of discharge anticoagulation was associated with differences between those with vein vs prosthetic conduits in overall survival, primary patency, risk of amputation, or risk of major adverse limb events (MALE). A multivariable Cox proportional hazards analysis was performed to control for differences in baseline demographic factors between the groups. RESULTS: During the study period (2003-2020), 57,887 patients underwent infra-geniculate bypass. Of these, 3230 (5.5%) were anticoagulated on discharge. There was a similar distribution of anticoagulation between vein (n = 1659; 51.4%) and prosthetic conduits (n = 1571; 48.6%). Thirty-two percent were discharged on DOACs, and 68.0% were discharged on warfarin. For prosthetic conduits, being discharged on a DOAC was associated with improved outcomes on univariate and multivariable analyses revealing lower risk of overall mortality (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.41-0.93; P = .021), loss of primary patency (HR, 0.70; 95% CI, 0.55-0.89; P = .003), risk of amputation (HR, 0.71; 95% CI, 0.54-0.93; P = .013), and risk of MALE (HR, 0.80; 95% CI, 0.64-1.00; P = .048). Patients with a vein bypass had improved univariate outcomes for survival and primary patency; however, with multivariable analysis, there were no significant differences in outcomes between DOAC and warfarin. CONCLUSIONS: Anticoagulation-naive patients who underwent an infra-geniculate prosthetic bypass had higher rates of overall survival, bypass patency, amputation-free survival, and freedom from MALE when discharged on a DOAC compared with warfarin. Those with vein bypasses had similar outcomes regardless of the choice of anticoagulation.

Predictors of prolonged length of stay after elective carotid revascularization.

OBJECTIVE: Postoperative day-one discharge is used as a quality-of-care indicator after carotid revascularization. This study identifies predictors of prolonged length of stay (pLOS), defined as a postprocedural LOS of >1 day, after elective carotid revascularization. METHODS: Patients undergoing carotid endarterectomy (CEA), transcarotid artery revascularization (TCAR), and transfemoral carotid artery stenting (TFCAS) in the Vascular Quality Initiative between 2016 and 2022 were included in this analysis. Multivariable logistic regression analysis was used to identify predictors of pLOS, defined as a postprocedural LOS of >1 day, after each procedure. RESULTS: A total of 118,625 elective cases were included. pLOS was observed in nearly 23.2% of patients undergoing carotid revascularization. Major adverse events, including neurological, cardiac, infectious, and bleeding complications, occurred in 5.2% of patients and were the most significant contributor to pLOS after the three procedures. Age, female sex, non-White race, insurance status, high comorbidity index, prior ipsilateral CEA, non-ambulatory status, symptomatic presentation, surgeries occurring on Friday, and postoperative hypo- or hypertension were significantly associated with pLOS across all three procedures. For CEA, additional predictors included contralateral carotid artery occlusion, preoperative use of dual antiplatelets and anticoagulation, low physician volume (<11 cases/year), and drain use. For TCAR, preoperative anticoagulation use, low physician case volume (<6 cases/year), no protamine use, and post-stent dilatation intraoperatively were associated with pLOS. One-year analysis showed a significant association between pLOS and increased mortality for all three procedures; CEA (hazard ratio [HR],1.64; 95% confidence interval [CI], 1.49-1.82), TCAR (HR,1.56; 95% CI, 1.35-1.80), and TFCAS (HR, 1.33; 95%CI, 1.08-1.64) (all P < .05). CONCLUSIONS: A postoperative LOS of more than 1 day is not uncommon after carotid revascularization. Procedure-related complications are the most common drivers of pLOS. Identifying patients who are risk for pLOS highlights quality improvement strategies that can optimize short and 1-year outcomes of patients undergoing carotid revascularization.

Secondary interventions following open vs endovascular revascularization for chronic limb threatening ischemia in the BEST-CLI trial.

OBJECTIVES: Patients undergoing revascularization for chronic limb-threatening ischemia experience a high burden of target limb reinterventions. We analyzed data from the Best Endovascular versus Best Surgical Therapy in Patients with Critical Limb Ischemia (BEST-CLI) randomized trial comparing initial open bypass (OPEN) and endovascular (ENDO) treatment strategies, with a focus on reintervention-related study endpoints. METHODS: In a planned secondary analysis, we examined the rates of major reintervention, any reintervention, and the composite of any reintervention, amputation, or death by intention-to-treat assignment in both trial cohorts (cohort 1 with suitable single-segment great saphenous vein [SSGSV], n = 1434; cohort 2 lacking suitable SSGSV, n = 396). We also compared the cumulative number of major and all index limb reinterventions over time. Comparisons between treatment arms within each cohort were made using univariable and multivariable Cox regression models. RESULTS: In cohort 1, assignment to OPEN was associated with a significantly reduced hazard of a major limb reintervention (hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.28-0.49; P < .001), any reintervention (HR, 0.63; 95% CI, 0.53-0.75; P < .001), or any reintervention, amputation, or death (HR, 0.68; 95% CI, 0.60-0.78; P < .001). Findings were similar in cohort 2 for major reintervention (HR, 0.53; 95% CI, 0.33-0.84; P = .007) or any reintervention (HR, 0.71; 95% CI, 0.52-0.98; P = .04). In both cohorts, early (30-day) limb reinterventions were notably higher for patients assigned to ENDO as compared with OPEN (14.7% vs 4.5% of cohort 1 subjects; 16.6% vs 5.6% of cohort 2 subjects). The mean number of major (mean events per subject ratio [MR], 0.45; 95% CI, 0.34-0.58; P < .001) or any target limb reinterventions (MR, 0.67; 95% CI, 0.57-0.80; P < .001) per year was significantly less in the OPEN arm of cohort 1. The mean number of reinterventions per limb salvaged per year was lower in the OPEN arm of cohort 1 (MR, 0.45; 95% CI, 0.35-0.57; P < .001 and MR, 0.66; 95% CI, 0.55-0.79; P < .001 for major and all, respectively). The majority of index limb reinterventions occurred during the first year following randomization, but events continued to accumulate over the duration of follow-up in the trial. CONCLUSIONS: Reintervention is common following revascularization for chronic limb-threatening ischemia. Among patients deemed suitable for either approach, initial treatment with open bypass, particularly in patients with available SSGSV conduit, is associated with a significantly lower number of major and minor target limb reinterventions.

Seven years of the transcarotid artery revascularization surveillance project, comparison to transfemoral stenting and endarterectomy.

OBJECTIVE: This study utilizes the latest data from the Vascular Quality Initiative (VQI), which now encompasses over 50,000 transcarotid artery revascularization (TCAR) procedures, to offer a sizeable dataset for comparing the effectiveness and safety of TCAR, transfemoral carotid artery stenting (tfCAS), and carotid endarterectomy (CEA). Given this substantial dataset, we are now able to compare outcomes overall and stratified by symptom status across revascularization techniques. METHODS: Utilizing VQI data from September 2016 to August 2023, we conducted a risk-adjusted analysis by applying inverse probability of treatment weighting to compare in-hospital outcomes between TCAR vs tfCAS, CEA vs tfCAS, and TCAR vs CEA. Our primary outcome measure was in-hospital stroke/death. Secondary outcomes included myocardial infarction and cranial nerve injury. RESULTS: A total of 50,068 patients underwent TCAR, 25,361 patients underwent tfCAS, and 122,737 patients underwent CEA. TCAR patients were older, more likely to have coronary artery disease, chronic kidney disease, and undergo coronary artery bypass grafting/percutaneous coronary intervention as well as prior contralateral CEA/CAS compared with both CEA and tfCAS. TfCAS had higher odds of stroke/death when compared with TCAR (2.9% vs 1.6%; adjusted odds ratio [aOR], 1.84; 95% confidence interval [CI], 1.65-2.06; P < .001) and CEA (2.9% vs 1.3%; aOR, 2.21; 95% CI, 2.01-2.43; P < .001). CEA had slightly lower odds of stroke/death compared with TCAR (1.3% vs 1.6%; aOR, 0.83; 95% CI, 0.76-0.91; P < .001). TfCAS had lower odds of cranial nerve injury compared with TCAR (0.0% vs 0.3%; aOR, 0.00; 95% CI, 0.00-0.00; P < .001) and CEA (0.0% vs 2.3%; aOR, 0.00; 95% CI, 0.0-0.0; P < .001) as well as lower odds of myocardial infarction compared with CEA (0.4% vs 0.6%; aOR, 0.67; 95% CI, 0.54-0.84; P < .001). CEA compared with TCAR had higher odds of myocardial infarction (0.6% vs 0.5%; aOR, 1.31; 95% CI, 1.13-1.54; P < .001) and cranial nerve injury (2.3% vs 0.3%; aOR, 9.42; 95% CI, 7.78-11.4; P < .001). CONCLUSIONS: Although tfCAS may be beneficial for select patients, the lower stroke/death rates associated with CEA and TCAR are preferred. When deciding between CEA and TCAR, it is important to weigh additional procedural factors and outcomes such as myocardial infarction and cranial nerve injury, particularly when stroke/death rates are similar. Additionally, evaluating subgroups that may benefit from one procedure over another is essential for informed decision-making and enhanced patient care in the treatment of carotid stenosis.

Emergence of lumpy skin disease virus (LSDV) infection in domestic Himalayan yaks (Bos grunniens) in Himachal Pradesh, India.

In this study, we investigated and confirmed natural lumpy skin disease virus (LSDV) infection in Himalayan yaks (Bos grunniens) in Himachal Pradesh, India, based on clinical manifestations and results of genome detection, antibody detection, virus isolation, and nucleotide sequencing. Subsequent phylogenetic analysis based on complete GPCR, RPO30, and EEV gene sequences revealed that the LSDV isolates from these yaks and local cattle belonged to LSDV subcluster 1.2.1 rather than the dominant subcluster 1.2.2, which is currently circulating in India, suggesting a separate recent introduction. This is the first report of natural LSDV infection in yaks in India, expanding the known host range of LSDV. Further investigations are needed to assess the impact of LSDV infection in yaks.

DIRECTIONAL OPTICAL COHERENCE TOMOGRAPHY IMAGING OF MACULAR PATHOLOGY.

PURPOSE: To survey the impact of directional reflectivity on structures within optical coherence tomography images in retinal pathology. METHODS: Sets of commercial optical coherence tomography images taken from multiple pupil positions were analyzed. These directional optical coherence tomography sets revealed directionally reflective structures within the retina. After ensuring sufficient image quality, resulting hybrid and composite images were characterized by assessing the Henle fiber layer, outer nuclear layer, ellipsoid zone, and interdigitation zone. Additionally, hybrid images were reviewed for novel directionally reflective pathological features. RESULTS: Cross-sectional directional optical coherence tomography image sets were obtained in 75 eyes of 58 patients having a broad range of retinal pathologies. All cases showed improved visualization of the outer nuclear layer/Henle fiber layer interface, and outer nuclear layer thinning was, therefore, more apparent in several cases. The ellipsoid zone and interdigitation zone also demonstrated attenuation where a geometric impact of underlying pathology affected their orientation. Misdirected photoreceptors were also noted as a consistent direction-dependent change in ellipsoid zone reflectivity between regions of normal and absent ellipsoid zone. CONCLUSION: Directional optical coherence tomography enhances the understanding of retinal anatomy and pathology. This optical contrast yields more accurate identification of retinal structures and possible imaging biomarkers for photoreceptor-related pathology.

Functional Return-to-Sport Testing Demonstrates Inconsistency in Predicting Short-Term Outcomes Following Anterior Cruciate Ligament Reconstruction: A Systematic Review.

PURPOSE: To systematically review the relationship between functional testing at the time of return to sport (RTS) and short-term outcomes, such as second anterior cruciate ligament (ACL) tear and return to a preinjury level of sport, among athletes who underwent anterior cruciate ligament reconstruction (ACLR). METHODS: A systematic literature search was performed in MEDLINE, EMBASE, Scopus, and Web of Science to identify studies examining athletes who underwent functional RTS testing and were followed for at least 12 months following ACLR. Studies were screened by 2 reviewers. A standardized template was used to extract information regarding study characteristics, ACLR information, functional test results, and risk factors associated with retear or reduced RTS. RESULTS: Of the 937 studies identified, 22 met the inclusion criteria. The average time between ACLR and RTS testing was 8.5 months. Single leg hop for distance performance had no association with retear risk in any study and no association with RTS rates in most studies. Quadriceps strength had conflicting results in relation to retear risk, whereas it had no relationship with RTS rates. Rates of reinjury and RTS were similar between patients who passed and did not pass combined hop and strength batteries. Asymmetric knee extension and hip moments, along with increased knee valgus and knee flexion angles, demonstrated increased risk of retear. CONCLUSIONS: Individual hop and strength tests that are often used in RTS protocols following ACLR may have limited and inconsistent value in predicting ACL reinjury and reduced RTS when used in isolation. Combined hop and strength test batteries also demonstrate low sensitivity and negative predictive value, highlighting conflicting evidence to suggest RTS testing algorithm superiority. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV studies.

Athletes Continue to Show Functional Performance Deficits at Return to Sport After Anterior Cruciate Ligament Reconstruction: A Systematic Review.

PURPOSE: To systematically review the existing literature on the functional performance of athletes at the time of return-to-sport (RTS) clearance after anterior cruciate ligament reconstruction (ACLR). METHODS: A systematic literature search of the MEDLINE, EMBASE, Scopus, and Web of Science databases was performed. The inclusion criteria were original research reports with study populations of athletes who had undergone ACLR and had undergone objective functional testing immediately after clearance to RTS. Functional testing was stratified by hop tests, strength tests, kinetic assessment, and kinematic assessment, and data were extracted from each study using a standardized template. RESULTS: Of the 937 unique studies identified, 46 met the inclusion criteria. The average time between ACLR and functional testing was 7.9 months among the included studies. In 10 of 17 studies, patients were found to have an average quadriceps strength limb symmetry index of less than 90%. However, only 2 of 12 studies found the average hop test limb symmetry index to be less than 90%. Kinematics included reduced knee flexion angle and increased trunk flexion on landing in ACLR patients compared with matched controls. On evaluation of kinetics, ACLR patients showed reduced peak vertical ground reaction force, lower peak knee extension and knee flexion moments, and altered energy absorption contribution compared with matched controls. CONCLUSIONS: This systematic review suggests that athletes show functional deficits at the time of RTS at an average of 7.9 months after ACLR. Traditional functional tests, such as strength and hop tests, are not able to accurately identify patients who continue to show deficits. The most common biomechanical deficits that persist after RTS clearance include diminished peak knee extension moment, decreased knee flexion angle, increased trunk flexion angle, reduced vertical ground reaction force, and increased hamstring central activation ratio during various functional gait and landing tasks. LEVEL OF EVIDENCE: Level III, systematic review of Level I to III studies.

Meniscectomy Reimbursement and Utilization Are Declining at Different Rates Across the United States.

PURPOSE: To evaluate how arthroscopic meniscectomy utilization, reimbursement, physician billing practices, and patient populations have changed within the Medicare population from 2013 to 2021 at a national level and regional level. METHODS: The Medicare Physician & Other Practitioners database was queried for all episodes of 2-compartment and single-compartment arthroscopic meniscectomy between 2013 and 2021. Utilization per 10,000 beneficiaries and average inflation-adjusted reimbursement were assessed. Physician practice styles, measured through changes in the services billed, and Medicare beneficiary demographic characteristics were extracted each year. The Kruskal-Wallis test was performed to compare regions. RESULTS: Between 2013 and 2021, two-compartment meniscectomy utilization per 10,000 Medicare beneficiaries declined by 54.9% and single-compartment meniscectomy utilization declined by 54.2%. Average reimbursement declined by 9.3% and 12.5% for 2-compartment meniscectomy and single-compartment meniscectomy, respectively. In 2021, the South had the highest utilization of both 2-compartment (3.8/10,000) and single-compartment (4.7/10,000) meniscectomies while having the lowest average reimbursement for 2-compartment meniscectomy ($383.02, P < .001). Nationally, the average number of beneficiaries per surgeon performing single-compartment meniscectomy declined by 3.8% whereas the average number of billable services performed per beneficiary increased by 46.6%. The comorbidity risk score of these patients decreased by 8.7%, with the West having the healthiest patients in 2021. CONCLUSIONS: Meniscectomy utilization and reimbursement have been declining nationally within the Medicare population. Surgeons in the South performed the most meniscectomies while having among the lowest reimbursement. The practice patterns of surgeons performing meniscectomies have been changing, with surgeons performing nearly 50% more total billable services per beneficiary while performing fewer unique billable services. Additionally, the patient population of surgeons who perform meniscectomy was healthier in 2021 than in 2013. CLINICAL RELEVANCE: This study highlights changes in meniscectomy utilization and reimbursement over time in the face of changing evidence of meniscectomy use in elderly patients and new Medicare legislature regarding reimbursement.

Regional differences in reimbursement, volume, and patient characteristics exist for rotator cuff repairs: a temporal analysis from 2013 to 2021.

BACKGROUND: Prior studies have demonstrated declining reimbursement and changing procedural utilization across multiple orthopedic subspecialties, yet a comprehensive examination of this has not been performed for rotator cuff repair (RCR), particularly at a geographic level. The purpose of this study was to evaluate changes in reimbursement, utilization, and patient populations for open and arthroscopic RCRs from 2013 to 2021 at a national and regional level. METHODS: The Medicare Physician and Other Practitioners database from years 2013 to 2021 were queried to extract all episodes of open chronic RCR, open acute RCR, and arthroscopic RCR. Utilization was measured as procedural volume per 10,000 Medicare beneficiaries. Inflation-adjusted reimbursement, utilization, surgeon information, and patient characteristics were extracted for each procedure for each year. Data was stratified geographically based on US Census regions and rural-urban commuting codes. Kruskal-Wallis tests and linear regressions were performed to compare geographical areas. RESULTS: Between 2013 and 2021, arthroscopic RCR utilization increased by 9.4% (11.0/10,000-12.0/10,000), while open chronic RCR utilization decreased by 58.8% (2.0/10,000-0.8/10,000). During that time, average inflation-adjusted reimbursement declined by 10.0% and 11.3% for arthroscopic and open chronic RCR, respectively. The increase in utilization and decrease in reimbursement was greatest in the Midwest. In 2021, arthroscopic RCR utilization was 12.0/10,000, while average reimbursement was $846.87, nationally. Utilization was highest in the South (14.5/10,000) and lowest in the Northeast (8.1/10,000) (P < .001). Alternatively, reimbursement was highest in the Northeast ($904.60) and lowest in the South ($830.80) (P < .001). The proportion of patients who were male, Medicaid eligible, or non-White was highest in the West (P < .001). Patients in the West also had the fewest comorbidities. Increased patient comorbidities, when controlling patient demographics, were associated with lower reimbursement nationally and within the Northeast (P < .001). CONCLUSION: Geographical discrepancies in RCR utilization and reimbursement exist. The South consistently demonstrates the highest utilization of RCR, while also having the lowest reimbursement. Alternatively, the Northeast has the lowest utilization but the highest reimbursement. Increased patient population comorbidities were associated with reduced RCR reimbursement for surgeons in the Northeast, but not in other regions.

Regional variation from 2013 to 2021 in primary total shoulder arthroplasty utilization, reimbursement, and patient populations.

BACKGROUND: Total shoulder arthroplasty (TSA), encompassing both anatomical and reverse TSA, has increased in popularity worldwide. The purpose of this study was to assess how TSA utilization, reimbursement, surgeon practices, and patient populations have evolved within the Medicare population from 2013 to 2021 at a national and regional level. METHODS: The Medicare Physician and Other Practitioners dataset was queried for all episodes of primary TSA (CPT-23472), both anatomic and reverse, between years 2013 and 2021. TSA utilization was assessed as volume per 10,000 Medicare beneficiaries. Average inflation-adjusted reimbursement, physician practice styles, and patient demographics of each TSA surgeon were extracted each year. Data were stratified geographically based on US census classifications and rural-urban commuting codes. Kruskal-Wallis and multivariate regressions were utilized to determine differences between regions. RESULTS: Between 2013 and 2021 TSA utilization increased by 121.8%, nationally. The increase was greatest in the Northeast (+147.2%) and least in the Midwest (+115.5%). Average TSA reimbursement declined by 8.8% nationally, with the least decline in the Northeast (6.4%) and the greatest decline in the Midwest (-11.9%). In 2021, the Midwest had the highest TSA utilization (18.1/10,000), while having the lowest average reimbursement ($1108.59; P < .001). The Northeast had the lowest utilization (11.5/10,000) and highest reimbursement ($1223.44; P < .001) in 2021. Nationally, the number of Medicare beneficiaries per surgeon performing shoulder arthroplasty declined by 5.9%, while the average number of TSAs per surgeon (+8.5%) and average number of billable services per beneficiary (+16.6%) both increased. Surgeons in the South performed the most services per beneficiary in 2021 (9.0; P < .001). The average comorbidity burden of patients was decreased by 4.8% between 2013 and 2021, with the West having the healthiest patients in 2021. Higher patient comorbidities were associated with lower physician reimbursement nationally (P < .001). CONCLUSION: This study demonstrates that TSA utilization in the Medicare population has more than doubled between 2013 and 2021, while average inflation-adjusted reimbursement has declined by nearly 10%. The Midwest has the highest per-capita TSA utilization, while simultaneously having the lowest average reimbursement per TSA. Over time, TSA surgeons are seeing fewer and healthier beneficiaries but performing more services per beneficiary. Additionally, increased patient complexity may be associated with lower reimbursement. Together, these findings are concerning for long-term equitable access to care within shoulder surgery.

Differences in Reimbursements, Procedural Volumes, and Patient Characteristics Based on Surgeon Gender in Total Hip Arthroplasty.

BACKGROUND: Prior studies have suggested there may be differences in reimbursement and practice patterns by gender. The purpose of this study was to comprehensively evaluate differences in reimbursement, procedural volume, and patient characteristics in total hip arthroplasty (THA) between men and women surgeons from 2013 to 2021. METHODS: The Medicare Physician and Other Practitioners database from 2013 to 2021 was queried. Inflation-adjusted reimbursement, procedural volume, surgeon information, and patient demographics were extracted for surgeons performing over 10 primary THAs each year. Wilcoxon, t-tests, and multivariate linear regressions were utilized to compare men and women surgeons. RESULTS: Only 1.4% of THAs billed to Medicare between 2013 and 2021 were billed by women surgeons. Men surgeons earned significantly greater reimbursement nationally in 2021 compared to women surgeons per THA ($1,018.56 versus $954.17, P = .03), but no difference was found when assessing each region separately. Reimbursement declined at similar rates for both men and women surgeons (-18.3 versus -19.8%, P = .38). An increase in the proportion of women surgeons performing THA between 2013 and 2021 was seen in all regions except the South. In 2021, the proportion of all THAs performed by women surgeons was highest in the West (3.5%) and lowest in the South (1.0%). Women surgeons had comparable patient populations in terms of age, race, comorbidity status, and Medicaid eligibility to their men counterparts, but performed significantly fewer services per beneficiary (5.6 versus 8.1, P < .001) and fewer unique services (51.1 versus 69.6, P < .001). CONCLUSIONS: Average reimbursement per THA has declined at a similar rate for men and women physicians between 2013 and 2021. Women's representation in THA surgery nationwide has nearly doubled between 2013 and 2021, with the greatest increase in the West. However, there are notable differences in billing practices between genders.