Spinal Versus General Anesthesia for Outpatient Total Hip and Knee Arthroplasty in the Ambulatory Surgery Center: A Matched-Cohort Study.

BACKGROUND: Spinal anesthesia is the predominant regimen in outpatient total joint arthroplasty (TJA), but induction often is unsuccessful, unobtainable, or against patient preference. We compared outcomes of same-day discharge (SDD) TJA with spinal versus general anesthesia in a free-standing ambulatory surgery center (ASC). METHODS: We took 105 general anesthesia TJA and one-to-one nearest-neighbor matched them to 105 spinal anesthesia TJA over 7 years at 1 ASC. The rate of successful SDD, minutes to discharge, postoperative pain and nausea, and 90-day complications were compared. Postanesthesia care unit outcomes were additionally stratified by spinal anesthetic (mepivacaine versus bupivacaine). RESULTS: All spinal anesthetic patients underwent SDD compared with 103 (98%) general anesthetic patients (P = .498). Mepivacaine spinal anesthesia patients spent the fewest minutes in postanesthesia care unit prior to discharge from the facility (206), followed by general anesthesia (227), and bupivacaine spinal anesthesia (291; P < .001). General anesthesia patients had the highest levels of pain at 1 hour (5.2 versus 1.5 versus 1.5) and 2 hours (3.2 versus 2.0 versus 1.3) postoperatively, and rates of nausea (48 versus 22 versus 28%) compared with mepivacaine and bupivacaine spinal anesthesia, respectively. The 90-day complications (6 versus 7), admissions (1 versus 3), and reoperations (5 versus 2) were similar among spinal and general anesthesia, respectively (P ≥ .445). CONCLUSIONS: Both spinal and general anesthesia led to reliable SDD with similar 90-day complication rates. General anesthesia facilitated faster discharge from the ASC compared with bupivacaine spinal anesthesia but led to higher levels of pain and incidence of nausea postoperatively. LEVEL OF EVIDENCE: Level 3, Retrospective Cohort Comparison.

Comparison of triamcinolone and methylprednisolone efficacy and steroid flare reaction rates after shoulder corticosteroid injection: a prospective interrupted time series study.

BACKGROUND: A corticosteroid flare reaction is a well-described phenomenon that causes significant pain and dysfunction. The paucity of literature impedes decision making regarding which corticosteroid to use for shoulder injection. The purpose of this study was to compare methylprednisolone acetate (MPA) and triamcinolone acetonide (TA) injections in the glenohumeral joint and/or subacromial space in terms of efficacy and the incidence of steroid flare reactions. METHODS: In this prospective, interrupted time series, parallel study, patients received injections in the glenohumeral joint and/or subacromial space. MPA and TA were used during 2 discrete 3-month periods. The injections consisted of 2 mL of lidocaine, 2 mL of bupivacaine, and 80 mg of either MPA or TA. Visual analog scale (VAS) pain scores were recorded immediately before injection; 1-7 days after injection; and 3, 6, and 12 months after injection. The primary outcome was the incidence of a steroid flare reaction, defined as a post-injection increase in the VAS score by ≥2 points. The secondary outcome was injection failure, defined as a post-injection VAS score greater than the baseline score or the need for another intervention. We used linear mixed models with a patient-level random intercept to identify the mean VAS score change for TA injections in the first week after injection. RESULTS: MPA or TA shoulder injections were administered in 421 patients; of these patients, 15 received bilateral-joint injections whereas 406 received a single-joint injection, for a total of 436 injections (209 MPA and 227 TA injections). Pain scores in the first week after injection were available for 193 MPA and 199 TA injections. Significantly more patients in the MPA cohort reported flare reactions compared with the TA cohort (22.8% vs. 4.0%, P < .001) during the first week after injection. In the first week after injection, the mean VAS score of patients receiving TA injections was 1.05 (95% confidence interval, 0.47-1.63) lower than that of patients receiving MPA injections when adjusted for age, sex, race, pain type, surgeon type, and injection site. At 3 months, surveys for 169 MPA and 172 TA injections were completed, with no significant difference in the rate of injection failure for MPA vs. TA (42.6% vs. 36.1%, P = .224). Treatment failure rates were significantly higher for MPA than for TA at 6 months (78.44% vs. 62.5%, P < .001) but not at 12 months (81.18% vs. 81.42%, P = .531.) CONCLUSION: TA injections resulted in a >5-fold reduction in steroid flare reactions, with statistically superior 6-month efficacy rates, compared with MPA injections. This study supports TA as a more viable corticosteroid option for shoulder injection.

The Incidence of Posterolateral Tibial Plateau and Central Lateral Femoral Condylar Impaction Fractures in a Pediatric and Young Adult Population.

BACKGROUND: Posterolateral tibial plateau and central lateral femoral condylar impaction fractures are known to occur in the setting of anterior cruciate ligament (ACL) tears. There have been no prior investigations into the incidence and morphology of posterolateral tibial plateau impaction fractures in the setting of ACL injury in a pediatric population. METHODS: Patients between 9 and 22 years of age with knee magnetic resonance imagings (MRIs) performed demonstrating complete or partial ACL tear were included in this study. MRI reports were reviewed to denote the presence of posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament injury, meniscus tears, cartilage lesions. MRIs were reviewed by 2 fellowship-trained orthopaedic surgeons to denote the presence of posterolateral tibial plateau and central lateral femoral condylar impaction fractures and physeal status of femoral and tibial physes. Statistical analysis performed included χ 2 analysis and the Student t testing. RESULTS: A total of 328 patients with a primary ACL tear were identified. The mean age of patients included was 16.5 years (range: 9.0-21.5). The incidence of posterolateral tibial plateau impaction fractures was 83/328 (25.3%) while the incidence of lateral femoral condylar impaction fractures was 119/328 (36.3%). Bipolar impaction fractures occurred in 37/328 (11.3%). Of the 83 tibial impaction fractures identified, 82 were low-grade morphologic subtypes. Patients with lateral tibial plateau impaction fractures were older than those with no fracture (17.2±2.2 vs. 16.3±2.1, P =0.001). Only 3/38 (7.9%) patients with an open tibial physis sustained a tibial plateau impaction fracture compared with 80/290 (27.6%) with a closed tibial physis (χ 2 value: 6.9, P =0.009). There was no difference in proportion of patients with lateral femoral condylar impaction fractures based on femoral physeal status ( P =0.484). CONCLUSION: The incidence of posterolateral tibial plateau impaction fractures in the setting of ACL tear in a pediatric and young adult patient population appears to be lower while lateral femoral condylar impaction fractures occur more frequently when comparing to previously reported incidences found in adult populations in the literature. Furthermore, posterolateral tibial plateau impaction fractures occur less frequently in those with an open proximal tibial physis and high-grade posterolateral tibial plateau bone loss is exceedingly rare in pediatric and young adult patients. Lateral femoral condylar impaction fractures are associated with lateral meniscal tears and medial meniscal ramp lesions. LEVEL OF EVIDENCE: Level IV-cross-sectional study.

Deep-Learning-Assisted Focused Ion Beam Nanofabrication.

Focused ion beam (FIB) milling is an important rapid prototyping tool for micro- and nanofabrication and device and materials characterization. It allows for the manufacturing of arbitrary structures in a wide variety of materials, but establishing the process parameters for a given task is a multidimensional optimization challenge, usually addressed through time-consuming, iterative trial-and-error. Here, we show that deep learning from prior experience of manufacturing can predict the postfabrication appearance of structures manufactured by focused ion beam (FIB) milling with >96% accuracy over a range of ion beam parameters, taking account of instrument- and target-specific artifacts. With predictions taking only a few milliseconds, the methodology may be deployed in near real time to expedite optimization and improve reproducibility in FIB processing.

Motion control for laser machining via reinforcement learning.

Laser processing techniques such as laser machining, marking, cutting, welding, polishing and sintering have become important tools in modern manufacturing. A key step in these processes is to take the intended design and convert it into coordinates or toolpaths that are useable by the motion control hardware and result in efficient processing with a sufficiently high quality of finish. Toolpath design can require considerable amounts of skilled manual labor even when assisted by proprietary software. In addition, blind execution of predetermined toolpaths is unforgiving, in the sense that there is no compensation for machining errors that may compromise the quality of the final product. In this work, a novel laser machining approach is demonstrated, utilizing reinforcement learning (RL) to control and supervise the laser machining process. This autonomous RL-controlled system can laser machine arbitrary pre-defined patterns whilst simultaneously detecting and compensating for incorrectly executed actions, in real time.

Single-frame 3D lensless microscopic imaging via deep learning.

Since the pollen of different species varies in shape and size, visualizing the 3-dimensional structure of a pollen grain can aid in its characterization. Lensless sensing is useful for reducing both optics footprint and cost, while the capability to image pollen grains in 3-dimensions using such a technique could be truly disruptive in the palynology, bioaerosol sensing, and ecology sectors. Here, we show the ability to employ deep learning to generate 3-dimensional images of pollen grains using a series of 2-dimensional images created from 2-dimensional scattering patterns. Using a microscope to obtain 3D Z-stack images of a pollen grain and a 520 nm laser to obtain scattering patterns from the pollen, a single scattering pattern per 3D image was obtained for each position of the pollen grain within the laser beam. In order to create a neural network to transform a single scattering pattern into different 2D images from the Z-stack, additional Z-axis information is required to be added to the scattering pattern. Information was therefore encoded into the scattering pattern image channels, such that the scattering pattern occupied the red channel, and a value indicating the position in the Z-axis occupied the green and blue channels. Following neural network training, 3D images were formed from collated generated 2D images. The volumes of the pollen grains were generated with a mean accuracy of ∼84%. The development of airborne-pollen sensors based on this technique could enable the collection of rich data that would be invaluable to scientists for understanding mechanisms of pollen production climate change and effects on the wider public health.

Opioid-sparing pain management protocol after shoulder arthroplasty results in less opioid consumption and higher satisfaction: a prospective, randomized controlled trial.

BACKGROUND: The opioid epidemic has become a central focus in health care. In an effort to reduce opioid use, orthopedic surgeons use multimodal strategies to control postoperative pain. However, no clear consensus exists on ideal pain management strategies after shoulder arthroplasty, and most protocols are opioid-driven. This study sought to determine if patients undergoing shoulder arthroplasty using a postoperative opioid-sparing pain-control regimen would have equivalent pain scores and satisfaction as patients using a traditional opioid-based regimen. METHODS: Patients undergoing primary anatomic or reverse total shoulder arthroplasty were prospectively enrolled and randomized into an opioid-sparing (OS) or a traditional opioid-based (OB) postoperative pain protocol. Both groups received opioid education, periarticular injection with liposomal bupivacaine, and preoperative and postoperative multimodal management (acetaminophen, celecoxib, and gabapentin). The OB group was discharged with 40 oxycodone tablets and standard icing, whereas the OS group received ketorolac during admission, continuous cryotherapy, and discharged with 10 oxycodone tablets for rescue. Patients were queried regarding levels of pain and opioid consumption at days 1-7 and at 2, 6, and 12 weeks postoperatively. Patient satisfaction was recorded at 1, 2, 6, and 12 weeks. Range of motion (ROM), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and Single Assessment Numerical Evaluation (SANE) scores were assessed preoperatively and at 12 weeks postoperatively. Complications, readmissions, and reoperations were recorded. RESULTS: In 78 patients, no difference in VAS pain scores were seen at any time between groups. The OS group consumed less oral morphine equivalents (OME) from inpatient hospitalization to 12 weeks postoperatively (P < .05). Total OME consumption was reduced by 213% for the OS vs. the OB group (112 vs. 239; P < .0001). The OS group consumed fewer opioid pills at all time points (P < .05). A 395% reduction in number of opioid pills consumed in the first 12 weeks postoperatively was seen in the OS vs. the OB group (4.3 vs. 17.0; P < .0001). Significantly more patients in the OS group discontinued opioids by 2 weeks postoperatively (86.1% vs. 58.5%; P = .011), and 94.4% in the OS group discontinued opioids by 6 weeks postoperatively. The OS group was more satisfied with pain management at 1 and 6 weeks (P = .05). No difference in ROM, ASES or SANE scores, complications, readmissions, or reoperations were seen between groups. CONCLUSIONS: This study demonstrated a nearly 4-fold reduction in opioid pain pill consumption and earlier cessation of opioids with an OS pain management protocol. Patients also reported higher satisfaction with this pain management strategy.

Reliability Testing of the Mayo Elbow Performance Score in Post-operative Patients.

This study aimed to determine intra-observer and inter-observer reliability of the Mayo Elbow Performance Score (MEPS). Patients undergoing elbow surgery completed a MEPS questionnaire initially and another 2-3 weeks later. During the second interview, patients completed the Oxford Elbow Score (OES) for comparison. Intraclass correlation coefficients (ICC) and Pearson correlation coefficients (PCC) > 0.80 indicated substantial agreement. In 42 patients who had elbow surgery, the average MEPS score initially was 78 (range, 5-100, SD 22.4) and 77 (range, 5-100, SD 21.5) at second interview. The average normalized OES score was 79 (range, 17-100, SD 23.6). The ICC for MEPS scores at the two time points was 0.90, and the PCC between the MEPS and OES scores was 0.87, indicating substantial agreement. The MEPS has strong intra-observer reliability at different time points and strong inter-observer reliability when compared with the OES, validating the MEPS as an outcome measure of elbow surgery. (Journal of Surgical Orthopaedic Advances 31(4):229-232, 2022).

Predictive capabilities for laser machining via a neural network.

The interaction between light and matter during laser machining is particularly challenging to model via analytical approaches. Here, we show the application of a statistical approach that constructs a model of the machining process directly from experimental images of the laser machined sample, and hence negating the need for understanding the underlying physical processes. Specifically, we use a neural network to transform a laser spatial intensity profile into an equivalent scanning electron microscope image of the laser-machined target. This approach enables the simulated visualization of the result of laser machining with any laser spatial intensity profile, and hence demonstrates predictive capabilities for laser machining. The trained neural network was found to have encoded functionality that was consistent with the laws of diffraction, hence showing the potential of this approach for discovering physical laws directly from experimental data.

Ultrafast multi-layer subtractive patterning.

Subtractive femtosecond laser machining using multiple pulses with different spatial intensity profiles centred on the same position on a sample has been used to fabricate surface relief structuring. A digital micromirror device was used as an intensity spatial light modulator, with a fixed position relative to the sample, to ensure optimal alignment between successive masks. Up to 50 distinct layers, 335 nm lateral spatial resolution and 2.6 µm maximum depth structures were produced. The lateral dimensions of the structures are approximately 40 µm. Surface relief structuring is shown to match intended depth profiles in a nickel substrate, and highly repeatable stitching of identical features in close proximity is also demonstrated.

Real-time particle pollution sensing using machine learning.

Particle pollution is a global health challenge that is linked to around three million premature deaths per year. There is therefore great interest in the development of sensors capable of precisely quantifying both the number and type of particles. Here, we demonstrate an approach that leverages machine learning in order to identify particulates directly from their scattering patterns. We show the capability for producing a 2D sample map of spherical particles present on a coverslip, and also demonstrate real-time identification of a range of particles including those from diesel combustion.

Single-pulse ablation of multi-depth structures via spatially filtered binary intensity masks.

Digital micromirror devices (DMDs) show great promise for use as intensity spatial light modulators. When used in conjunction with pulsed lasers of a timescale below the DMD pixel switching time, DMDs are generally only used as binary intensity masks (i.e., "on" or "off" intensity for each mask pixel). In this work, we show that by exploiting the numerical aperture of an optical system during the design of binary masks, near-continuous intensity control can be accessed, whilst still maintaining high-precision laser-machining resolution. Complex features with ablation depths up to ∼60 nm, corresponding to grayscale values in bitmap images, are produced in single pulses via ablation with 150 fs laser pulses on nickel substrates, with lateral resolutions of ∼2.5 µm.

Sub-diffraction limit laser ablation via multiple exposures using a digital micromirror device.

We present the use of digital micromirror devices as variable illumination masks for pitch-splitting multiple exposures to laser machine the surfaces of materials. Ultrafast laser pulses of length 150 fs and 800 nm central wavelength were used for the sequential machining of contiguous patterns on the surface of samples in order to build up complex structures with sub-diffraction limit features. Machined patterns of tens to hundreds of micrometers in lateral dimensions with feature separations as low as 270 nm were produced in electroless nickel on an optical setup diffraction limited to 727 nm, showing a reduction factor below the Abbe diffraction limit of ∼2.7×. This was compared to similar patterns in a photoresist optimized for two-photon absorption, which showed a reduction factor of only 2×, demonstrating that multiple exposures via ablation can produce a greater resolution enhancement than via two-photon polymerization.

Pulsed laser deposited diode-pumped 7.4 W Yb:Lu2O3 planar waveguide laser.

Fabrication, characterization, and laser performance of an Yb:Lu2O3 planar waveguide laser are reported. Pulsed laser deposition was employed to grow an 8 µm-thick Yb-doped lutetia waveguide on a YAG substrate. X-ray diffraction was used to determine the crystallinity, and spectroscopic characterization showed the absorption and emission cross-sections were indistinguishable from those reported for bulk material. When end-pumped by a diode-laser bar an output power of 7.4 W was achieved, limited by the available pump power, at a wavelength of 1033 nm and a slope efficiency of 38% with respect to the absorbed pump power.

456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction.

In this Letter, we present a passively Q-switched Yb:Y2O3 waveguide laser using evanescent-field interaction with an atmospheric-pressure-chemical-vapor-deposited graphene saturable absorber. The waveguide, pumped by a broad area diode laser, produced an average output power of 456 mW at an absorbed power of 4.1 W. The corresponding pulse energy and peak power were 330 nJ and 2 W, respectively. No graphene damage was observed, demonstrating the suitability of top-deposited graphene for high-power operation.

Rapid bespoke laser ablation of variable period grating structures using a digital micromirror device for multi-colored surface images.

A digital micromirror device has been used to project variable-period grating patterns at high values of demagnification for direct laser ablation on planar surfaces. Femtosecond laser pulses of ∼1 mJ pulse energy at 800 nm wavelength from a Ti:sapphire laser were used to machine complex patterns with areas of up to ∼1 cm2 on thin films of bismuth telluride by dynamically modifying the grating period as the sample was translated beneath the imaged laser pulses. Individual ∼30 by 30 µm gratings were stitched together to form contiguous structures, which had diffractive effects clearly visible to the naked eye. This technique may have applications in marking, coding, and security features.

Diode-end-pumped 1.2 W Yb:Y2O3 planar waveguide laser.

Fabrication, characterization and laser performance of a Watt-level ytterbium-doped yttria waveguide laser is presented. The waveguide was grown onto a YAG substrate by pulsed laser deposition and features a 6 µm thick ytterbium-doped yttria layer sandwiched between two 3 µm undoped yttria layers. The laser deposited film was characterized by X-ray diffraction, showing a high degree of crystallinity and analyzed spectroscopically, showing performance indistinguishable from previously reported bulk material. When pumped with 8.5 W from a broad area diode laser the waveguide laser produces 1.2 W of output at 1030 nm.

Q-switched operation of a pulsed-laser-deposited Yb:Y(2)O(3) waveguide using graphene as a saturable absorber.

The first, to the best of our knowledge, Q-switched operation of a pulsed-laser-deposited waveguide laser is presented. A clad Yb:Y(2)O(3) waveguide was Q-switched using an output coupling mirror coated with a single layer of graphene deposited by atmospheric pressure chemical vapor deposition. During continuous-wave operation, a maximum power of 83 mW at a slope efficiency of 25% was obtained. During Q-switched operation, pulses as short as 98 ns were obtained at a repetition rate of 1.04 MHz and a central wavelength of 1030.8 nm.

Single-pulse multiphoton polymerization of complex structures using a digital multimirror device.

We present a rapid technique for the patterning of complex structures with ~2µm resolution via multiphoton polymerization, through use of a single ultrashort pulse in combination with the spatial intensity modulation possible from a digital multimirror device. Sub-micron features have been achieved through the use of ten consecutive pulses.

Laser operation of a Tm:Y2O3 planar waveguide.

We demonstrate the first Tm-doped yttria planar waveguide laser to our knowledge, grown by pulsed laser deposition. A maximum output power of 35 mW at 1.95 µm with 9% slope efficiency was achieved from a 12 µm-thick film grown on a Y(3)Al(5)O(12) substrate.