Effect of Stimulus Bandwidth on the Auditory Steady-State Response in Scalp- and Ear-EEG.

OBJECTIVES: The auditory steady-state response (ASSR) enables hearing threshold estimation based on electroencephalography (EEG) recordings. The choice of stimulus type has an impact on both the detectability and the frequency specificity of the ASSR. Amplitude modulated pure tones provide the most frequency-specific ASSR, but responses to pure tones are weak. The ASSR can be enhanced by increasing the bandwidth of the stimulus, but this comes at the cost of a decrease in the frequency specificity of the measured response. The objective of the present study is to investigate the relationship between stimulus bandwidth and ASSR amplitude. DESIGN: The amplitude of ASSR was measured for five types of stimuli: 1 kHz pure tone and band-pass noise with 1/3, 1/2, 1, and 2 octave bandwidths centered at 1 kHz. All stimuli were amplitude modulated with a 40 Hz sinusoid. Responses to all stimulus types were measured at 30, 40, and 50 dB SL. ASSRs were measured concurrently using both conventional scalp-EEG and ear-EEG. RESULTS: Stimulus bandwidth and sound intensity were both found to have a significant effect on the ASSR amplitude for scalp- and ear-EEG recordings. In scalp-EEG ASSRs to all bandwidth stimuli were found to be significantly larger than ASSRs to pure tone at low sound intensity. At higher sound intensities, however, significantly larger responses were only obtained for 1- and 2-octave bandwidth stimuli. In ear-EEG, only the ASSR to 2 octave bandwidth stimulus was significantly larger than the ASSR to amplitude modulated pure tones. CONCLUSIONS: At low presentation levels, even small increases in stimulus bandwidth (1/3 and 1/2 octave) improve the detectability of ASSR in scalp-EEG with little or no impact on the frequency specificity. In comparison, a larger increase in stimulus bandwidth was needed to improve the ASSR detectability in the ear-EEG recordings.

Ecdysone-dependent feedback regulation of prothoracicotropic hormone controls the timing of developmental maturation.

The activation of a neuroendocrine system that induces a surge in steroid production is a conserved initiator of the juvenile-to-adult transition in many animals. The trigger for maturation is the secretion of brain-derived neuropeptides, yet the mechanisms controlling the timely onset of this event remain ill-defined. Here, we show that a regulatory feedback circuit controlling the Drosophila neuropeptide Prothoracicotropic hormone (PTTH) triggers maturation onset. We identify the Ecdysone Receptor (EcR) in the PTTH-expressing neurons (PTTHn) as a regulator of developmental maturation onset. Loss of EcR in these PTTHn impairs PTTH signaling, which delays maturation. We find that the steroid ecdysone dose-dependently affects Ptth transcription, promoting its expression at lower concentrations and inhibiting it at higher concentrations. Our findings indicate the existence of a feedback circuit in which rising ecdysone levels trigger, via EcR activity in the PTTHn, the PTTH surge that generates the maturation-inducing ecdysone peak toward the end of larval development. Because steroid feedback is also known to control the vertebrate maturation-inducing hypothalamic-pituitary-gonadal axis, our findings suggest an overall conservation of the feedback-regulatory neuroendocrine circuitry that controls the timing of maturation initiation.

Beam damage in operando X-ray diffraction studies of Li-ion batteries.

Operando powder X-ray diffraction (PXRD) is a widely employed method for the investigation of structural evolution and phase transitions in electrodes for rechargeable batteries. Due to the advantages of high brilliance and high X-ray energies, the experiments are often carried out at synchrotron facilities. It is known that the X-ray exposure can cause beam damage in the battery cell, resulting in hindrance of the electrochemical reaction. This study investigates the extent of X-ray beam damage during operando PXRD synchrotron experiments on battery materials with varying X-ray energies, amount of X-ray exposure and battery cell chemistries. Battery cells were exposed to 15, 25 or 35 keV X-rays (with varying dose) during charge or discharge in a battery test cell specially designed for operando experiments. The observed beam damage was probed by µPXRD mapping of the electrodes recovered from the operando battery cell after charge/discharge. The investigation reveals that the beam damage depends strongly on both the X-ray energy and the amount of exposure, and that it also depends strongly on the cell chemistry, i.e. the chemical composition of the electrode.

Positron emission tomography visualized stimulation of the vestibular organ is localized in Heschl's gyrus.

The existence of a human primary vestibular cortex is still debated. Current knowledge mainly derives from functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) acquisitions during artificial vestibular stimulation. This may be problematic as artificial vestibular stimulation entails coactivation of other sensory receptors. The use of fMRI is challenging as the strong magnetic field and loud noise during MRI may both stimulate the vestibular organ. This study aimed to characterize the cortical activity during natural stimulation of the human vestibular organ. Two fluorodeoxyglucose (FDG)-PET scans were obtained after natural vestibular stimulation in a self-propelled chair. Two types of stimuli were applied: (a) rotation (horizontal semicircular canal) and (b) linear sideways movement (utriculus). A comparable baseline FDG-PET scan was obtained after sitting motion-less in the chair. In both stimulation paradigms, significantly increased FDG uptake was measured bilaterally in the medial part of Heschl's gyrus, with some overlap into the posterior insula. This is the first neuroimaging study to visualize cortical processing of natural vestibular stimuli. FDG uptake was demonstrated in the medial-most part of Heschl's gyrus, normally associated with the primary auditory cortex. This anatomical localization seems plausible, considering that the labyrinth contains both the vestibular organ and the cochlea.

Lead-Free Halide Double Perovskite Cs2 AgBiBr6 with Decreased Band Gap.

Environmentally friendly halide double perovskites with improved stability are regarded as a promising alternative to lead halide perovskites. The benchmark double perovskite, Cs2 AgBiBr6 , shows attractive optical and electronic features, making it promising for high-efficiency optoelectronic devices. However, the large band gap limits its further applications, especially for photovoltaics. Herein, we develop a novel crystal-engineering strategy to significantly decrease the band gap by approximately 0.26 eV, reaching the smallest reported band gap of 1.72 eV for Cs2 AgBiBr6 under ambient conditions. The band-gap narrowing is confirmed by both absorption and photoluminescence measurements. Our first-principles calculations indicate that enhanced Ag-Bi disorder has a large impact on the band structure and decreases the band gap, providing a possible explanation of the observed band-gap narrowing effect. This work provides new insights for achieving lead-free double perovskites with suitable band gaps for optoelectronic applications.

Prevalence of Postoperative Periprosthetic Femur Fractures Between Two Different Femoral Component Designs Used in Direct Anterior Total Hip Arthroplasty.

BACKGROUND: Periprosthetic femur fractures are a well-documented complication following direct anterior uncemented total hip arthroplasty. The purpose of this study is to compare the prevalence of postoperative periprosthetic femur fractures between 2 different femoral component designs used in direct anterior total hip arthroplasty. METHODS: Beginning in February 2015, a single fellowship-trained adult reconstruction surgeon performed 361 consecutive direct anterior total hip replacements using a flat, single-taper, wedged femoral implant. In June 2016, that same surgeon, using the exact same surgical technique and postoperative weight-bearing protocol, began using a dual-taper, hydroxyapatite-coated implant for 789 consecutive hips. The patients were carefully monitored for 3 months after surgery to identify the frequency of periprosthetic femur fractures. A Fisher's exact test was used to determine if the prevalence of periprosthetic femur fractures differed between the 2 implant designs. RESULTS: Five of 361 (1.4%) patients sustained proximal femur fractures at an average of 19.6 days postoperatively in the first group, all demonstrating a Vancouver type B2 periprosthetic fracture and requiring femoral revision. No patients (0/789, 0%) in the second cohort sustained a postoperative, periprosthetic fracture (P = .006). CONCLUSION: In this comparison of 2 consecutive cohorts, the dual-taper, hydroxyapatite-coated implant had a statistically significant lower postoperative periprosthetic fracture rate than a flat, single-taper, wedged design.

Is Physician Quality Reporting System Worth the Cost to Report to Center for Medicare and Medicaid Services?

BACKGROUND: The Center for Medicare and Medicaid Services (CMS) has proposed a move to payment based on patient-reported outcomes (PROs), and failure to report on PROs will result in a penalty of 2% in 2016. However, the cost to the physician to collect PROs is not known. METHODS: Using data from the 2013 Medical Group Management Association Compensation and Financial survey and Center for Medicare and Medicaid Services reimbursement, a calculation was performed to determine the cost to the physician to report on PROs for patients undergoing total knee arthroplasty and total hip arthroplasty. Using Medical Group Management Association and Medicare fee for service rates, calculations were performed based on an annual volume of 200 Medicare operative cases (125 total knee arthroplasties, 75 total hip arthroplasties) with 1000 new patients (level 4) and 2000 established patients (level 3) visits. A range of start-up and annual costs necessary to collect PROs including hardware, software, and personnel costs was calculated and then compared with the calculated 2% Medicare penalty for failing to report PROs in 2016. RESULTS: The cost to collect PROs ranged from $47,973 to $56,288 which far outweighed the penalty of $2954 in 2016 for failing to report these measures. CONCLUSION: With the move toward requiring surgeons to report PROs for reimbursement, the current financial model would prove to be cost prohibitive and the incentive to report PROs might be too costly to gain wide acceptance.

Greater Medial Compartment Forces During Total Knee Arthroplasty Associated With Improved Patient Satisfaction and Ability to Navigate Stairs.

BACKGROUND: The purpose of this study was to determine if postoperative patient satisfaction, subjective outcomes, and functional force testing differed between those with symmetric or asymmetric intraoperative mediolateral (ML) compressive forces. We hypothesized that the threshold would be similar to the previously reported valued of 15 lbf and that a significantly greater proportion of those with more symmetrical medial and lateral compressive forces would be satisfied with their total knee arthroplasty. METHODS: A commercially available instrumented trial tibial liner was used to measure ML compressive force differences with the knee at 0°, 20°, and 90°. Patient satisfaction and Knee Society Scores were compared between patients with ML asymmetries above and below the calculated optimal threshold. RESULTS: Surprisingly, lower ML asymmetries in extension were associated with a greater risk of being dissatisfied. Of the 50 total knee arthroplasties, 6 of 23 (26%) with ML force asymmetries <10 lbf were dissatisfied compared with 0 of 27 with ML asymmetries >10 lbf (P = .01). Greater asymmetry was associated with significantly greater gains in EQ-5D scores (P = .05) and pain scores (P = .03) and greater pain relief (P = .006) and reduced impact forces when navigating stairs (P = .05). CONCLUSION: Contrary to our hypotheses, the results of this study support the concept that recreating greater forces in the medial compartment much like that of the native knee may yield improved patient-reported outcomes and increased patient satisfaction. The current results further suggest that recreating greater medial compartment forces may have the greatest affect on more demanding activities such as navigating stairs.

Subchondral Bone Marrow Edema Had Greater Effect on Postoperative Pain After Medial Unicompartmental Knee Arthroplasty Than Total Knee Arthroplasty.

BACKGROUND: Although the relationship between pain and bone marrow edema (BME) in the osteoarthritic knee has been established, little is known about the effect of preoperative BME on postoperative outcomes after knee arthroplasty or if the influence of BME on postoperative outcomes differs between medial unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). The purpose of this study was to compare pain, patient satisfaction, and revision rates between medial UKA and TKA patients with and without magnetic resonance imaging evidence of BME in the proximal tibia. METHODS: We identified 71 patients (72 knees) from our prospective outcomes database with magnetic resonance images taken before undergoing either medial UKA or TKA and recorded the absence or presence of tibial BME. We then compared preoperative and postoperative Knee Society pain scores, patient satisfaction, and revisions between groups of UKA and TKA patients with or without preoperative tibial BME. RESULTS: Pain scores for UKA patients with BME were worse both before and after surgery, whereas TKA patients with BME demonstrated greater postoperative improvements in pain scores when compared to TKA patients without BME. Similarly, significantly fewer UKA patients with BME were satisfied with their procedure than those without BME (8/11, 73% vs 17/17, 100%; P = .05), but BME did not affect patient satisfaction after TKA. CONCLUSION: Preoperative BME did not influence TKA outcomes; however, pain scores for UKA patients with BME were worse both before and after surgery and fewer UKA patients with preoperative tibial BME were satisfied with their surgery.

An Intact Anterior Cruciate Ligament at the Time of Posterior Cruciate Ligament-Retaining Total Knee Arthroplasty Was Associated With Reduced Patient Satisfaction and Inferior Pain and Stair Function.

BACKGROUND: Patients with an intact anterior cruciate ligament (ACL) at the time of ACL-sacrificing total knee arthroplasty (TKA) have been suggested to have inferior outcomes compared with those with a dysfunctional ACL. However, to date, no published clinical studies have evaluated the potential link between the condition of the ACL at the time of posterior cruciate ligament-retaining TKA and postoperative pain, function, and satisfaction. As such, the purpose of this study was to compare subjective function, movement-elicited pain, pain at rest, and patient satisfaction between those with an intact or dysfunctional ACL. METHODS: We identified 562 posterior cruciate ligament-retaining TKAs with complete intraoperative and postoperative data. Patients were categorized based on the condition of the ACL at the time of TKA as either being intact or dysfunctional (absent or lax). Knee Society Function Scores, movement-elicited pain, pain at rest, and patient satisfaction were then compared between groups. RESULTS: At mean follow-up of 5.1 years, a significantly lower proportion of patients in the intact group were satisfied with their operation (intact: 391/453 [86.3%] vs dysfunctional: 102/109 [93.6%], P = .0496). Inspection of the individual activities revealed that the groups did not differ in walking ability or pain when walking; however, the intact group reported significantly reduced ability to navigate stairs with greater pain during that activity. CONCLUSION: The lack of difference in pain at rest between groups suggests that pain and functional impairments during more demanding activities such as navigating stairs may be associated with the lost function of the ACL rather than by altered central pain processing.

The Location and Severity of Preoperative Subchondral Bone Marrow Lesions Were Not Associated With Inferior Postoperative Outcomes After Medial Unicompartmental Knee Arthroplasty or Total Knee Arthroplasty.

BACKGROUND: Inferior outcomes for medial unicompartmental knee arthroplasty (UKA) patients with preoperative medial tibial bone marrow lesions (BMLs) were recently reported. The purpose of this study was to compare the location and severity of BML on postoperative outcomes after medial UKA and TKA using a larger sample size and more rigorous magnetic resonance imaging (MRI) evaluation. METHODS: BML were graded on preoperative MRIs from 174 UKAs performed between 2009 and 2013 using the MRI Osteoarthritis Knee Score criteria. Grading was performed by a single evaluator blinded to the patient's outcome. MRIs from a matched group of 174 TKAs were then evaluated. Preoperative and postoperative Knee Society Knee Scores, Pain Scores, and Function Scores (FSs) were then compared between UKA and TKA patients based on the location and severity of BMLs. RESULTS: Overall medial-side BML severity (sum of tibia, femur, and patellar grades) did not affect Pain Score or FS; however, UKA and TKA patients with more severe BMLs had greater preoperative-to-postoperative gains in Knee Society Knee Scores (P = .05). When evaluating individual regions, UKA patients with more severe medial tibial BML had significantly greater gains in FS than those without BML, whereas the opposite was true for TKA patients (P = .02). Similarly, UKA and TKA patients with patellar lesions had greater gains in FS than those without BML (P = .05). Medial femoral BML did not appear to affect outcomes for either UKA or TKA patients. CONCLUSION: Medial tibial BMLs were not associated with inferior outcomes. Clinically, these results suggest that BMLs should not be considered a contraindication for medial UKA.

Better than fish on land? Hearing across metamorphosis in salamanders.

Early tetrapods faced an auditory challenge from the impedance mismatch between air and tissue in the transition from aquatic to terrestrial lifestyles during the Early Carboniferous (350 Ma). Consequently, tetrapods may have been deaf to airborne sounds for up to 100 Myr until tympanic middle ears evolved during the Triassic. The middle ear morphology of recent urodeles is similar to that of early 'lepospondyl' microsaur tetrapods, and experimental studies on their hearing capabilities are therefore useful to understand the evolutionary and functional drivers behind the shift from aquatic to aerial hearing in early tetrapods. Here, we combine imaging techniques with neurophysiological measurements to resolve how the change from aquatic larvae to terrestrial adult affects the ear morphology and sensory capabilities of salamanders. We show that air-induced pressure detection enhances underwater hearing sensitivity of salamanders at frequencies above 120 Hz, and that both terrestrial adults and fully aquatic juvenile salamanders can detect airborne sound. Collectively, these findings suggest that early atympanic tetrapods may have been pre-equipped to aerial hearing and are able to hear airborne sound better than fish on land. When selected for, this rudimentary hearing could have led to the evolution of tympanic middle ears.

Hearing of the African lungfish (Protopterus annectens) suggests underwater pressure detection and rudimentary aerial hearing in early tetrapods.

In the transition from an aquatic to a terrestrial lifestyle, vertebrate auditory systems have undergone major changes while adapting to aerial hearing. Lungfish are the closest living relatives of tetrapods and their auditory system may therefore be a suitable model of the auditory systems of early tetrapods such as Acanthostega. Therefore, experimental studies on the hearing capabilities of lungfish may shed light on the possible hearing capabilities of early tetrapods and broaden our understanding of hearing across the water-to-land transition. Here, we tested the hypotheses that (i) lungfish are sensitive to underwater pressure using their lungs as pressure-to-particle motion transducers and (ii) lungfish can detect airborne sound. To do so, we used neurophysiological recordings to estimate the vibration and pressure sensitivity of African lungfish (Protopterus annectens) in both water and air. We show that lungfish detect underwater sound pressure via pressure-to-particle motion transduction by air volumes in their lungs. The morphology of lungfish shows no specialized connection between these air volumes and the inner ears, and so our results imply that air breathing may have enabled rudimentary pressure detection as early as the Devonian era. Additionally, we demonstrate that lungfish in spite of their atympanic middle ear can detect airborne sound through detection of sound-induced head vibrations. This strongly suggests that even vertebrates with no middle ear adaptations for aerial hearing, such as the first tetrapods, had rudimentary aerial hearing that may have led to the evolution of tympanic middle ears in recent tetrapods.

Comparison of Patient Function during the First Six Weeks after Direct Anterior or Posterior Total Hip Arthroplasty (THA): A Randomized Study.

The purpose of this single-surgeon randomized study was to determine if functional recovery during the early postoperative period differs between the direct anterior (DAA) and posterior approaches (PA). An a priori power analysis indicated that 26 patients per group were needed, and 6-week follow-up data were available for 51 THAs to date. Hospitals stays were significantly shorter for the DAA group (1.4 vs. 2.0 days, P=0.01), and the change in Pain Scores was significantly greater for the DAA group (P=0.04). The DAA group also discontinued use of an assistive ambulatory device at an earlier time (33.0 vs. 43.1 days, P=0.03). Despite these differences, no other subjective or objective functional measures differed between the 2 groups at the 6-week follow-up.

Patients with Pain 60 to 120 Days after Total Knee Arthroplasty More Likely to be Dissatisfied at Mid-Term Follow-Up.

The purpose of this study was to determine if TKA patients with pain between 60 and 120 days are more likely to be dissatisfied at mid-term follow-up. At the 60-120 day follow-up, moderate to severe movement-elicited pain (MEP) and pain at rest (PAR) were reported by 25/316 TKAs (7.9%) and 44/316 TKAs (13.9%), respectively. A greater proportion of those with MEP at 60-120 days were dissatisfied at midterm follow-up (24% vs. 6.5%, P = .01), and those with MEP early after surgery were 4.5 times more likely to be dissatisfied at mid-term follow-up (P = .004). Similarly, those with PAR 60-120 days after surgery were 4.1 times more likely to be dissatisfied at mid-term follow-up (P = .002).

Assessing the utility of routine first annual follow-up visits after primary total knee arthroplasty.

The combination of increased TKA utilization and a decreased number of arthroplasty specialists has resulted in a growing need to maximize efficiency without sacrificing the level of care being provided. The purpose of this study was to evaluate the utility of routine first annual follow-up visits for patients that have undergone primary TKA. Of 339 TKAs performed by a single surgeon in 2012, 23% failed to attend scheduled first annual visits. Furthermore, none of the revisions performed at our facility since 2003 were the direct result of information gained at a patient's routine first annual visit. As such, we question the clinical utility of the first annual visit.

Chronic Non-Orthopedic Conditions More Common in Patients with Less Severe Degenerative Changes That Have Elected to Undergo Total Knee Arthroplasty.

The purpose of this study was to determine whether the prevalence of chronic non-orthopedic conditions that may play a role in an abnormal pain response differs between patients based on the severity of degenerative changes at the time of surgery. Of 1020 OA knees that had undergone primary TKA with a minimum 2year follow-up, we identified 117 (11.5%) that had less severe degenerative changes. The prevalence of dissatisfaction was significantly greater in less severe group compared to those with moderate or severe changes (18.8% vs. 9.3%, P=.003). Chronic non-orthopedic conditions were significantly more prevalent in the less severe group with 41.9% reporting depression/anxiety, 30.8% with fibromyalgia or low back pathology, and 12.8% with a prior traumatic brain injury or stroke.

Factors influencing patient satisfaction two to five years after primary total knee arthroplasty.

Between 15% and 20% of primary total knee arthroplasty (TKA) patients have been reported to be dissatisfied with the procedure. With 2 to 5 year follow-up of 768/959 (80%) cruciate-retaining TKAs performed by a single surgeon, we evaluated the prevalence of dissatisfied patients and determined which factors were most related to patient satisfaction. Of the 768 TKAs, 80 were dissatisfied with their procedure (10.4%). Postoperative Knee Society Pain Scores and passive knee flexion were most related to a lack of satisfaction. Age, gender, and BMI did not appear to be related to patient satisfaction. By and large, dissatisfied patients in the current study had not experienced improvements in passive flexion, Pain Scores, or Function Scores when compared to their preoperative state.

Greater prevalence of wound complications requiring reoperation with direct anterior approach total hip arthroplasty.

The purpose of this retrospective study was to compare wound complication rates between primary THAs performed via a posterior or direct anterior approach. From our prospective outcomes registry, we identified 1288 primary THAs performed via a posterior approach and 505 via a direct anterior approach. The direct anterior approach resulted in a significantly greater number of wound complications that required reoperation than the posterior approach (7/505 (1.4%) vs. 3/1,288 (0.2%), P=0.007). As such, patients should be counseled on the potential increased risk of early wound complications with the direct anterior approach, and future research is needed to determine if alternative closure techniques can reduce the risk of wound complication.

Patient and intraoperative factors influencing satisfaction two to five years after primary total knee arthroplasty.

The purpose of this study was to compare patient demographics and factors recorded at the time of surgery between patients that were either satisfied or dissatisfied with their TKA at mid-term follow-up. From our prospective outcomes database, 989 primary TKAs with complete preoperative and intraoperative data were identified. At mean follow-up of 3.5 years, 94/989 TKAs (9.5%) were not satisfied with their TKA. African American patients were 3.0 times more likely to be dissatisfied than Caucasians (95% CI = 1.5-6.0, P = .003). Patients with less severe degenerative changes were 2.1 times more likely to be dissatisfied (95% CI = 1.3-3.2, P = .001).