The characteristics and predictors of mortality in periprosthetic fractures around the knee.

Aims: Periprosthetic fractures (PPFs) around the knee are challenging injuries. This study aims to describe the characteristics of knee PPFs and the impact of patient demographics, fracture types, and management modalities on in-hospital mortality. Methods: Using a multicentre study design, independent of registry data, we included adult patients sustaining a PPF around a knee arthroplasty between 1 January 2010 and 31 December 2019. Univariate, then multivariable, logistic regression analyses were performed to study the impact of patient, fracture, and treatment on mortality. Results: Out of a total of 1,667 patients in the PPF study database, 420 patients were included. The in-hospital mortality rate was 6.4%. Multivariable analyses suggested that American Society of Anesthesiologists (ASA) grade, history of peripheral vascular disease (PVD), history of rheumatic disease, fracture around a loose implant, and cerebrovascular accident (CVA) during hospital stay were each independently associated with mortality. Each point increase in ASA grade independently correlated with a four-fold greater mortality risk (odds ratio (OR) 4.1 (95% confidence interval (CI) 1.19 to 14.06); p = 0.026). Patients with PVD have a nine-fold increase in mortality risk (OR 9.1 (95% CI 1.25 to 66.47); p = 0.030) and patients with rheumatic disease have a 6.8-fold increase in mortality risk (OR 6.8 (95% CI 1.32 to 34.68); p = 0.022). Patients with a fracture around a loose implant (Unified Classification System (UCS) B2) have a 20-fold increase in mortality, compared to UCS A1 (OR 20.9 (95% CI 1.61 to 271.38); p = 0.020). Mode of management was not a significant predictor of mortality. Patients managed with revision arthroplasty had a significantly longer length of stay (median 16 days; p = 0.029) and higher rates of return to theatre, compared to patients treated nonoperatively or with fixation. Conclusion: The mortality rate in PPFs around the knee is similar to that for native distal femur and neck of femur fragility fractures. Patients with certain modifiable risk factors should be optimized. A national PPF database and standardized management guidelines are currently required to understand these complex injuries and to improve patient outcomes.

Predictors of mortality in periprosthetic fractures of the hip: Results from the national PPF study.

INTRODUCTION: Periprosthetic fractures (PPFs) around the hip joint are increasing in prevalence. In this collaborative study, we aimed to investigate the impact of patient demographics, fracture characteristics, and modes of management on in-hospital mortality of PPFs involving the hip. METHODS: Using a multi-centre cohort study design, we retrospectively identified adults presenting with a PPF around the hip over a 10-year period. Univariate and multivariable logistic regression analyses were performed to study the independent correlation between patient, fracture, and treatment factors on mortality. RESULTS: A total of 1,109 patients were included. The in-hospital mortality rate was 5.3%. Multivariable analyses suggested that age, male sex, abbreviated mental test score (AMTS), pneumonia, renal failure, history of peripheral vascular disease (PVD) and deep surgical site infection were each independently associated with mortality. Each yearly increase in age independently correlates with a 7% increase in mortality (OR 1.07, p=0.019). The odds of mortality was 2.99 times higher for patients diagnosed with pneumonia during their hospital stay [OR 2.99 (95% CI 1.07-8.37) p=0.037], and 7.25 times higher for patients that developed renal failure during their stay [OR 7.25 (95% CI 1.85-28.47) p=0.005]. Patients with history of PVD have a six-fold greater mortality risk (OR 6.06, p=0.003). Mode of treatment was not a significant predictor of mortality. CONCLUSION: The in-hospital mortality rate of PPFs around the hip exceeds 5%. The fracture subtype and mode of management are not independent predictors of mortality, while patient factors such as age, AMTS, history of PVD, pneumonia, and renal failure can independently predict mortality. Peri-operative optimisation of modifiable risk factors such as lung and kidney function in patients with PPFs around the hip during their hospital stay is of utmost importance.

Resonant Mixing Dynamic Nuclear Polarization.

We propose a mechanism for dynamic nuclear polarization that is different from the well-known Overhauser effect, solid effect, cross effect, and thermal mixing processes. We term it Resonant Mixing (RM), and we show that it arises from the evolution of the density matrix for a simple electron-nucleus coupled spin pair subject to weak microwave irradiation, the same interactions as the solid effect. However, the SE is optimal when the microwave field is off-resonance, whereas RM is optimal when the microwave field is on-resonance and involves the mixing of states by the microwave field together with the electron-nuclear coupling. Finally, we argue that this mechanism is responsible for the observed dispersive-shaped DNP field profile for trityl samples near the electron paramagnetic resonance center.

High aspect ratio diamond nanosecond laser machining.

Laser processing of diamond has become an important technique for fabricating next generation microelectronic and quantum devices. However, the realization of low taper, high aspect ratio structures in diamond remains a challenge. We demonstrate the effects of pulse energy, pulse number and irradiation profile on the achievable aspect ratio with 532 nm nanosecond laser machining. Strong and gentle ablation regimes were observed using percussion hole drilling of type Ib HPHT diamond. Under percussion hole drilling a maximum aspect ratio of 22:1 was achieved with 10,000 pulses. To reach aspect ratios on average 40:1 and up to 66:1, rotary assisted drilling was employed using > 2 M pulse accumulations. We additionally demonstrate methods of obtaining 0.1° taper angles via ramped pulse energy machining in 10:1 aspect ratio tubes. Finally, effects of laser induced damage are studied using confocal Raman spectroscopy with observation of up to 36% increase in tensile strain following strong laser irradiation. However, we report that upon application of 600 °C heat treatment, induced strain is reduced by up to ~ 50% with considerable homogenization of observed strain. Supplementary Information: The online version contains supplementary material available at 10.1007/s00339-023-06755-2.

Diamond rotors.

The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5-2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ωr/2π = 111.000 ±â€¯0.004 kHz, with stable spinning up to 124 kHz, using N2 gas as the driving fluid. We present the first proton-detected 13C/15N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (∼10:1) precluded fabrication of MAS rotors from diamond.

Amplified Overhauser DNP with Selective Deuteration: Attenuation of Double-Quantum Cross-Relaxation.

We recently used selective 2H labeling of BDPA to investigate the Overhauser Effect (OE) dynamic nuclear polarization (DNP) mechanism in insulating solids doped with 1,3-bis(diphenylene)-2-phenylallyl (BDPA), and established that the α and γ 1H spins on the fluorene rings are responsible for generating a zero quantum (ZQ) mediated positive bulk polarization. Here, we establish that the phenyl 1H spins relax via double-quantum (DQ) processes and therefore contribute negative enhancements which attenuate the OE-DNP. With measurements at different magnetic field strengths, we show that phenyl-d5-BDPA offers >50% improvement in OE-DNP enhancement compared to h21-BDPA attaining a maximum of ∼90 at 14.1 T and 5 kHz MAS, the highest observed OE-DNP enhancement to date under these conditions. The approach may be utilized to optimize other polarizing agents exhibiting an OE, an important DNP mechanism with a favorable field and spinning frequency dependence.

The Effectiveness of Whole Lung Lavage in Pneumoconiosis: A Systematic Review and Meta-Analysis.

OBJECTIVE: This study aimed to evaluate the role of whole lung lavage (WLL) in the treatment of pneumoconiosis and compare changes in lung function over time in treated and untreated miners. METHODS: We systematically reviewed and identified eight controlled studies with treated and comparison groups with lung function tests before WLL and a year or more later. Two hundred ninety-two patients were included in our meta-analysis. RESULTS: Studies consistently showed a slowing of the rate of lung function decline with WLL at 1, 2, and 4 years. In some reports, details of the population under study, reliability of lung function tests, the adequacy of matching, technical aspects of the procedure, and adverse effects associated with WLL were not available. CONCLUSIONS: Despite recognized weaknesses in the presentation of information, this procedure may show promise in altering the natural history of pneumoconiosis.

Primary total hip replacement using Burch-Schneider cages for acetabular fractures.

INTRODUCTION: Osteoporotic acetabular fractures are common and pose a difficult technical challenge for the trauma surgeon. Acute total hip arthroplasty (THA) using a Burch-Schneider antiprotrusio cage with immediate postoperative weight-bearing is a method to approach these injuries. This case series reports our outcomes of acute THA using Burch-Schneider cages for acetabular fractures from a UK major trauma centre based on length of stay, radiological outcome, complications and outcome scores. METHODS: Data were collected from all patients who underwent acute THA with a Burch-Schneider cage for acetabular fractures between June 2006 and August 2015. Patients were followed up clinically, radiologically, and using Oxford Hip Scores (OHS). RESULTS: 20 patients with a median age of 73 (range 60-90 years) were identified. All patients were independent walkers at follow-up, and had achieved radiological union. There were no dislocations, subsidence, revision or deep infections. Significant complications include 1 perioperative death as a result of complications arising from pre-existing pulmonary fibrosis; 1 deep vein thrombosis; 1 intraoperative arterial injury to the superior gluteal artery; and 1 leg-length discrepancy. Mean length of stay was 10 days. The mean OHS was 37/48 at a mean follow-up of 26 months. CONCLUSIONS: This case series further validates the use of Burch-Schneider cages with primary THA in acute acetabular fractures.

3D-printed stators & drive caps for magic-angle spinning NMR.

3D printing has evolved into an invaluable tool for rapid and cost-effective production of intricate parts. In this paper we describe 3D printing and other rapid prototyping methods to fabricate 3.2 mm stators and drive caps for use in magic angle spinning (MAS) NMR experiments. These components can be fabricated with the assistance of computer-aided design (CAD) software and at a fraction of the cost of commercial parts. Additionally, we show that the performance of these 3D printed stators and drive caps is comparable to commercially available systems and that they have significant advantages over their machined counterparts.

Inhalational Constrictive Bronchiolitis: The Evolution of our Understanding of this Disease.

The case definition of inhalational constrictive bronchiolitis (CB) has changed over the generations. We identify changes in the description of this illness over time associated with different exposures and present the natural history of CB in a case attributed to military burn pit exposure. The initial descriptions of this disease began with nitric acid spills and silage exposures. In these events, there was an acute exposure, typically a short-term resolution of the adverse respiratory events, and then a progression, leading to disability or a respiratory death. The life-saving role of corticosteroid therapy in this situation was recognized. War gas exposures of World War I and then Saddam Hussein's use of sulfur mustard gas in the Iran-Iraq War followed. More recently the findings associated with diacetyl exposure in commercial popcorn workers remained consistent with previously described presentations, but then the clinical presentation in troops returning from deployment to Southwest Asia was very different, yet with the same histologic findings. We recognize unreconciled disparities in the clinical, physiologic, and imaging presentation in those with inhalational bronchiolitis and acknowledge this as perhaps one of the difficult diagnoses in respiratory medicine.

Constrictive Bronchiolitis Attributable to Inhalation of Toxic Agents: Considerations for a Case Definition.

OBJECTIVE: We identified cases of constrictive bronchiolitis (CB), an inflammatory injury obliterating the small airways, in adults caused by inhalational exposure to determine an appropriate case definition. METHODS: We performed a systematic review with meta-analysis for these cases from 1990 to 2017. Publications were included if there was 1) inhalational exposure; 2) respiratory symptoms/signs; 3) pulmonary function test results; and 4) computerized tomographic chest imaging. Many had a lung biopsy. RESULTS: Two hundred seventy-four articles were retrieved; 22 manuscripts comprising 102 cases were included. Diagnostic criteria from cases associated with military deployment to southwest Asia were statistically different from criteria of other etiologies. CONCLUSION: In three cases, the scan was consistent with CB, the biopsy nondiagnostic, yet the diagnosis was made. CB associated with military deployment presented with diagnostic features statistically different from features in the other cases.

Characterizing anomalous diffusion in crowded polymer solutions and gels over five decades in time with variable-lengthscale fluorescence correlation spectroscopy.

The diffusion of macromolecules in cells and in complex fluids is often found to deviate from simple Fickian diffusion. One explanation offered for this behavior is that molecular crowding renders diffusion anomalous, where the mean-squared displacement of the particles scales as 〈r(2)〉∝t(α) with α < 1. Unfortunately, methods such as fluorescence correlation spectroscopy (FCS) or fluorescence recovery after photobleaching (FRAP) probe diffusion only over a narrow range of lengthscales and cannot directly test the dependence of the mean-squared displacement (MSD) on time. Here we show that variable-lengthscale FCS (VLS-FCS), where the volume of observation is varied over several orders of magnitude, combined with a numerical inversion procedure of the correlation data, allows retrieving the MSD for up to five decades in time, bridging the gap between diffusion experiments performed at different lengthscales. In addition, we show that VLS-FCS provides a way to assess whether the propagator associated with the diffusion is Gaussian or non-Gaussian. We used VLS-FCS to investigate two systems where anomalous diffusion had been previously reported. In the case of dense cross-linked agarose gels, the measured MSD confirmed that the diffusion of small beads was anomalous at short lengthscales, with a cross-over to simple diffusion around ≈1 µm, consistent with a caged diffusion process. On the other hand, for solutions crowded with marginally entangled dextran molecules, we uncovered an apparent discrepancy between the MSD, found to be linear, and the propagators at short lengthscales, found to be non-Gaussian. These contradicting features call to mind the "anomalous, yet Brownian" diffusion observed in several biological systems, and the recently proposed "diffusing diffusivity" model.

Clinical aspects of asbestos-related diseases--what are the unresolved topics?

OBJECTIVE: Despite awareness of the health risks associated with asbestos fiber inhalation and the decline in U.S. utilization (about 0.1% of the yearly peak amount), illnesses associated with exposure persist. Those with disease typically describe excessive exposures in the remote past, yet excessive exposures can occur today, most likely related to careless asbestos abatement procedures. The intent is to address unanswered questions associated with asbestos exposure. METHODS: The author summarizes clinical information addressing the case definition of asbestosis, the world-wide rate of mesothelioma, and clinical follow-up for those with exposure. RESULTS: The author describes information relevant to issues which remain unresolved. CONCLUSION: Perhaps somewhat surprisingly, even though there have been a great number of manuscripts reporting on the health risks of asbestos exposure, there remain unanswered questions regarding the pathogenesis of this disease.

Intra-Articular Synovial Haemangioma of the Elbow in an Adolescent Male.

Intra-articular haemangiomas are rare phenomena and are difficult to diagnose and manage. We describe a case in which a haemangioma was found at the time of elbow arthroscopy in an adolescent male. The case highlights the advantage of early arthroscopic assessment and also that synovial haemangiomas must be considered as a rare differential diagnosis in unexplained elbow and joint pain.

The effect of a clinical medical librarian on in-patient care outcomes.

OBJECTIVE: The research sought to determine the effect of a clinical medical librarian (CML) on outcomes of in-patients on the internal medicine service. METHODS: A prospective study was performed with two internal medicine in-patient teams. Team 1 included a CML who accompanied the team on daily rounds. The CML answered questions posed at the point of care immediately or in emails post-rounds. Patients on Team 2, which did not include a CML, as well as patients who did not require consultation by the CML on Team 1, served as the control population. Numerous clinical and library metrics were gathered on each question. RESULTS: Patients on Team 1 who required an answer to a clinical question were more ill and had a longer length of stay, higher costs, and higher readmission rates compared to those in the control group. Using a matched pair analysis, we showed no difference in clinical outcomes between the intervention group and the control group. CONCLUSIONS: This study is the largest attempt to prospectively measure changes in patient outcomes when physicians were accompanied by a CML on rounds. This approach may serve as a model for further studies to define when and how CMLs are most effective.

Assessing the FACTTS: an evidence-based medicine and critical appraisal course for medical students.

The Fourth-year Academic Clinical Training and Teaching Selective (FACTTS) is a course taught by medical and library faculty on the practice of evidence-based medicine and critical appraisal of the medical literature. This study assesses the impact of the course on students' understanding of the subject matter by examining three years of pre- and post-test data and addresses whether the number of sessions in the course affects the knowledge gained by the students. The data show an improvement in the students' understanding of course material, but no benefit was found in having two versus three sessions.

Morning report: can an established medical education tradition be validated?

BACKGROUND: Morning report is accepted as an essential component of residency education throughout different parts of the world. OBJECTIVE: To review the evidence of the educational value, purpose, methods, and outcomes of morning report. METHODS: A literature search of PubMed, Ovid, and the Cochrane Library for English-language studies published between January 1, 1966, and October 31, 2011, was performed. We searched for keywords and Medical Subject Heading terms related to medical education, methods, attitudes, and outcomes in regard to "morning report." Title and abstract review, followed by a full-text review by 3 authors, was performed to identify all pertinent articles. RESULTS: We identified 71 citations; 40 articles were original studies and 31 were commentaries, editorials, or review articles; 56 studies (79%) originated from internal medicine residency programs; 6 studies (8%) focused on ambulatory morning report; and 63 (89%) originated from the United States. Identified studies varied in objectives, methods, and outcome measures, and were not suitable for meta-analysis. Main outcome measures were resident satisfaction, faculty satisfaction, preparation for professional examinations, use of evidence-based medicine, clinical effects on patient care, adverse event detection, and utilization of a curriculum in case selection. CONCLUSIONS: Morning report has heterogeneous purposes, methods, and settings. As an educational tool, morning report is challenging to define, its outcome is difficult to measure, and this precludes firm conclusions about its contribution to resident education or patient care. Residency programs should tailor morning report to meet their own unique educational objectives and needs.

Magnetic resonance arthrography for labral tears and chondral wear in femoroacetabular impingement.

Magnetic resonance arthrography (MRA) is a useful pre-operative investigation for patients with clinical signs and symptoms of femoroacetabular impingement. Our aim was to assess the diagnostic accuracy of MRA in detecting labral tears and chondral wear in this context. Sixty nine hips were included in the study after exclusions. All patients underwent pre-operative MRA and then subsequent hip arthroscopy. The findings at MRA were compared to those found intraoperatively. For labral tears, sensitivity, specificity and accuracy were 81%, 51% and 58% respectively. For chondral wear these figures were 17%, 100%, and 55% respectively. In our institution, MRA was therefore not as accurate as previously published work suggests.