Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR

We use fits to recent published CPLEAR data on neutral kaon decays to $\pi^+\pi^-$ and $\pi e\nu$ to constrain the CPT--violation parameters appearing in a formulation of the neutral kaon system as an open quantum-mechanical system. The obtained upper limits of the CPT--violation parameters are approaching the range suggested by certain ideas concerning quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures

Experimental tests of CPT symmetry and quantum mechanics at CPLEAR

We review a phenomenological parametrization of an open quantum-mechanical formalism for CPT violation in the neutral kaon system, and constrain the parameters using fits to recent CPLEAR data.We review a phenomenological parametrization of an open quantum-mechanical formalism for CPT violation in the neutral kaon system, and constrain the parameters using fits to recent CPLEAR data

Experimental tests of CPT symmetry and quantum mechanics at CPLEAR

We review a phenomenological parametrization of an open quantum-mechanical formalism for CPT violation in the neutral kaon system, and constrain the parameters using fits to recent CPLEAR data

The CPLEAR detector at CERN

The CPLEAR collaboration has constructed a detector at CERN for an extensive programme of CP-, T- and CPT-symmetry studies using ${\rm K}^0$ and $\bar{\rm K}^0$ produced by the annihilation of $\bar{\rm p}$'s in a hydrogen gas target. The ${\rm K}^0$ and $\bar{\rm K}^0$ are identified by their companion products of the annihilation ${\rm K}^{\pm} \pi^{\mp}$ which are tracked with multiwire proportional chambers, drift chambers and streamer tubes. Particle identification is carried out with a liquid Cherenkov detector for fast separation of pions and kaons and with scintillators which allow the measurement of time of flight and energy loss. Photons are measured with a lead/gas sampling electromagnetic calorimeter. The required antiproton annihilation modes are selected by fast online processors using the tracking chamber and particle identification information. All the detectors are mounted in a 0.44 T uniform field of an axial solenoid of diameter 2 m and length 3.6 m to form a magnetic spectrometer capable of full on-line reconstruction and selection of events. The design, operating parameters and performance of the sub-detectors are described.

Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial

Background Arthroscopic sub-acromial decompression (decompressing the sub-acromial space by removing bone spurs and soft tissue arthroscopically) is a common surgery for subacromial shoulder pain, but its effectiveness is uncertain. We did a study to assess its effectiveness and to investigate the mechanism for surgical decompression. Methods We did a multicentre, randomised, pragmatic, parallel group, placebo-controlled, three-group trial at 32 hospitals in the UK with 51 surgeons. Participants were patients who had subacromial pain for at least 3 months with intact rotator cuff tendons, were eligible for arthroscopic surgery, and had previously completed a non-operative management programme that included exercise therapy and at least one steroid injection. Exclusion criteria included a full-thickness torn rotator cuff. We randomly assigned participants (1:1:1) to arthroscopic subacromial decompression, investigational arthroscopy only, or no treatment (attendance of one reassessment appointment with a specialist shoulder clinician 3 months after study entry, but no intervention). Arthroscopy only was a placebo as the essential surgical element (bone and soft tissue removal) was omitted. We did the randomisation with a computer-generated minimisation system. In the surgical intervention groups, patients were not told which type of surgery they were receiving (to ensure masking). Patients were followed up at 6 months and 1 year after randomisation; surgeons coordinated their waiting lists to schedule surgeries as close as possible to randomisation. The primary outcome was the Oxford Shoulder Score (0 [worst] to 48 [best]) at 6 months, analysed by intention to treat. The sample size calculation was based upon a target difference of 4·5 points (SD 9·0). This trial has been registered at ClinicalTrials.gov, number NCT01623011. Findings Between Sept 14, 2012, and June 16, 2015, we randomly assigned 313 patients to treatment groups (106 to decompression surgery, 103 to arthroscopy only, and 104 to no treatment). 24 [23%], 43 [42%], and 12 [12%] of the decompression, arthroscopy only, and no treatment groups, respectively, did not receive their assigned treatment by 6 months. At 6 months, data for the Oxford Shoulder Score were available for 90 patients assigned to decompression, 94 to arthroscopy, and 90 to no treatment. Mean Oxford Shoulder Score did not differ between the two surgical groups at 6 months (decompression mean 32·7 points [SD 11·6] vs arthroscopy mean 34·2 points [9·2]; mean difference −1·3 points (95% CI −3·9 to 1·3, p=0·3141). Both surgical groups showed a small benefit over no treatment (mean 29·4 points [SD 11·9], mean difference vs decompression 2·8 points [95% CI 0·5–5·2], p=0·0186; mean difference vs arthroscopy 4·2 [1·8–6·6], p=0·0014) but these differences were not clinically important. There were six study-related complications that were all frozen shoulders (in two patients in each group). Interpretation Surgical groups had better outcomes for shoulder pain and function compared with no treatment but this difference was not clinically important. Additionally, surgical decompression appeared to offer no extra benefit over arthroscopy only. The difference between the surgical groups and no treatment might be the result of, for instance, a placebo effect or postoperative physiotherapy. The findings question the value of this operation for these indications, and this should be communicated to patients during the shared treatment decision-making process. Funding Arthritis Research UK, the National Institute for Health Research Biomedical Research Centre, and the Royal College of Surgeons (England)

Relationship Between Timing of Anterior Cruciate Ligament Reconstruction and Chondral Injuries: A Systematic Review and Meta-analysis

Background: After anterior cruciate ligament (ACL) injury, the optimal timing of ACL reconstruction and the influence of this timing on chondral damage remain unclear. Purpose: To assess the effect of timing of ACL reconstruction on the presence of chondral injuries via a systematic review and meta-analysis. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: Two reviewers independently performed systematic literature searches of 5 online databases using the Cochrane methodology for systematic reviews. Eligibility criteria were any comparative study of patients aged >16 years that assessed the relationship between timing of primary ACL reconstruction surgery and rates of chondral injuries. Meta-analysis was conducted using a random-effects model. Results: After screening, 14 studies (n = 3559 patients) out of 2363 titles met the inclusion criteria: 3 randomized controlled trials (n = 272), 3 prospective cohort studies (n = 398), and 8 retrospective cohort studies (n = 2889). In analysis of the studies, chondral injury rates were compared between ACL reconstructions performed before and after 3 time points: 3, 6, and 12 months after injury (eg, ≤3 vs >3 months). The rates of chondral injury increased with each time point. The increase was mostly due to low-grade injuries at 3 months (estimated odds ratio, 1.914; 95% CI, 1.242-2.949; P =.003), with the increase in high-grade injuries becoming predominant after 12 months (estimated odds ratio, 3.057; 95% CI, 1.460-6.40; P =.003). Conclusion: Our findings suggest that delaying ACL reconstruction surgery results in a higher rate of chondral injuries and the severity of these lesions worsens with time. These findings are comparable with those of our previously published study, which demonstrated a higher risk of meniscal tears associated with delayed ACL surgery. When ACL reconstruction is indicated, surgery ≤3 months after injury is associated with a lower risk of intra-articular damage. Registration: CRD42016032846 (PROSPERO). © 2021 The Author(s)

COVID-19 infection is related to differences in the use of personal protective equipment by orthopaedic specialist trainees caring for hip fracture patients during the second surge of COVID-19 in the North West of England

Introduction Personal protective equipment (PPE) may protect health-care workers from COVID-19 infection and limit nosocomial spread to vulnerable hip fracture patients. Methods We performed a cross-sectional survey amongst orthopaedic trainees to explore PPE practice in 19 hospitals caring for hip fracture patients in the North West of England. Results During the second wave of the pandemic, 14/19 (74%) hospitals experienced an outbreak of COVID-19 amongst staff or patients on the orthopaedic wards. An FFP3 respirator mask was used by doctors in only 6/19 (32%) hospitals when seeing patients with COVID-19 and a cough and in 5/19 (26%) hospitals when seeing asymptomatic patients with COVID-19. A COVID-19 outbreak was reported in 11/13 (85%) orthopaedic units where staff wore fluid resistant surgical masks compared to 3/6 (50%) units using an FFP3 respirator mask (RR 1.69, 95% CI 0.74–3.89) when caring for symptomatic patients with COVID-19. Similarly, a COVID-19 outbreak was reported in more orthopaedic units caring for asymptomatic patients with COVID-19 where staff wore fluid resistant surgical masks (12/14 (86%)) as compared to an FFP3 respirator mask (2/5 (40%)) (RR 2.14, 95% CI 0.72–6.4). Conclusion Urgent re-evaluation of PPE use is required to reduce nosocomial spread of COVID-19, amongst highly vulnerable patients with hip fracture