Influence of increasing construct constraint in the presence of posterolateral deficiency at knee replacement: A biomechanical study

When faced with posterolateral corner (PLC) deficiency, surgeons must choose a total knee replacement (TKR) construct that provides the appropriate level of constraint. This should match the internal constraint of the device to the soft tissue host laxity pattern. Little guidance is available peroperatively, with factors influencing final component choice remaining ill defined. This study aimed to quantify the effect of PLC insufficiency on the “envelope of laxity” (EoL) after TKR and the effect of increasingly component constraint upon knee behavior through a functional arc of flexion. Using computer navigation, mixed effect modeling and loaded cadaveric legs—laxity was quantified under separate states: the native knee, after implantation of a posterior stabilized (PS)‐TKR, after sectioning the lateral (fibular) collateral ligament and popliteus tendon (PS‐TKR‐PLC), and after re‐implantation with a semi‐constrained “total stabilized” knee replacement (TS‐TKR). Laxity was quantified from 0 to 110° of flexion for anterior draw, varus–valgus, and internal–external rotation. Implantation of the PS‐TKR was consistently associated with increased constraint when compared to the native knee. PLC sectioning led to significantly increased laxity during varus stress from mid to deep flexion. Revision to a TS‐TKR construct restored constraint mimicking that of the primary state but only for the arc of motion 0–90°. In a posterolateral deficient state, a fixed bearing semi‐constrained TS‐TKR restored the knee to near normal kinematics but this was only achieved from an arc of motion 0–90° of flexion. At higher flexion angles, there remained an unfavorable laxity pattern with varus stress opening. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:427–434, 2016.     

Altered performance of reelin-receptor ApoER2 deficient mice on spatial tasks using the Barnes maze

The apolipoprotein E receptor 2 (ApoER2), expressed predominantly in forebrain regions including the hippocampus, is 1 of 2 receptors for the extracellular matrix protein reelin, which is critical for cortical development. Previous studies of ApoER2 mutant mice have indicated deficits in synaptic plasticity and learning. The current authors assessed learning and memory of ApoER2 knockout and wild-type mice on the Barnes circular maze. Mice were trained in this task for 22 days, followed by memory recall and reversal tests. ApoER2 knockout mice were initially slower to complete the task, but by Day 22 they were more accurate than wild-type mice on several indices. There were no differences in memory assessed by the recall task, but ApoER2 knockout mice performed significantly worse on the memory reversal task. ApoER2 knockout mice also displayed altered use of specific search strategies and relationship of these strategies to errors made on the maze.     

‘I’m on the train and I can't stop it': Western Canadians' reactions to prediabetes and the role of self‐compassion

Prediabetes, a condition characterised by impaired glucose regulation, is on the rise worldwide. This condition puts people at risk for cardiovascular disease, and 50% of people with prediabetes will develop type 2 diabetes (T2D). People with prediabetes can reduce their risk of developing T2D through lifestyle changes such as regular physical activity and healthy eating. However, the experience of health risks can be associated with negative reactions that can undermine people's ability to self‐regulate the health behaviours that would reduce such risk. Self‐compassion, or treating oneself kindly in the face of challenge, is known to help people manage negative emotions and facilitate self‐regulation. Therefore, self‐compassion may be helpful for people with prediabetes who have to manage their health behaviours in the context of a health threat. The purpose of this study was to explore how people, from a small Canadian city who learn that they have prediabetes, react emotionally to their prediabetes diagnosis. We also explored participants' receptivity to applying self‐compassion in the context of their prediabetes. Twenty‐one adults, recently notified by their doctors as having HbA1c scores indicative of prediabetes (M_age = 57.76, SD = 5.43), engaged in a semi‐structured interview between June 2017 and January 2018. Inductive thematic analysis was used to analyse the data and four themes emerged. Participants' reactions to learning that they had prediabetes were characterised by (a) distress and concern, (b) downplay of T2D risks, (c) guilt and shame, and participants were receptive to (d) self‐compassion as a beneficial approach to take in relation to their prediabetes. Findings suggest that people experience negative reactions to their prediabetes diagnosis yet are receptive to self‐compassion, which could mitigate these reactions. These findings can inform lifestyle behaviour change programmes for individuals living with prediabetes by providing a better understanding of their perspectives of disease diagnosis.     

A new risk prediction model for critical care: the Intensive Care National Audit & Research Centre (ICNARC) model

OBJECTIVE: To develop a new model to improve risk prediction for admissions to adult critical care units in the UK. DESIGN: Prospective cohort study. SETTING: The setting was 163 adult, general critical care units in England, Wales, and Northern Ireland, December 1995 to August 2003. PATIENTS: Patients were 216,626 critical care admissions. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The performance of different approaches to modeling physiologic measurements was evaluated, and the best methods were selected to produce a new physiology score. This physiology score was combined with other information relating to the critical care admission-age, diagnostic category, source of admission, and cardiopulmonary resuscitation before admission-to develop a risk prediction model. Modeling interactions between diagnostic category and physiology score enabled the inclusion of groups of admissions that are frequently excluded from risk prediction models. The new model showed good discrimination (mean c index 0.870) and fit (mean Shapiro's R 0.665, mean Brier's score 0.132) in 200 repeated validation samples and performed well when compared with recalibrated versions of existing published risk prediction models in the cohort of patients eligible for all models. The hypothesis of perfect fit was rejected for all models, including the Intensive Care National Audit & Research Centre (ICNARC) model, as is to be expected in such a large cohort. CONCLUSIONS: The ICNARC model demonstrated better discrimination and overall fit than existing risk prediction models, even following recalibration of these models. We recommend it be used to replace previously published models for risk adjustment in the UK.     

Who bounces back? Physiologic and other predictors of intensive care unit readmission

OBJECTIVE: To determine the influence of changes in acute physiology scores (APS) and other patient characteristics on predicting intensive care unit (ICU) readmission. DESIGN: Secondary analysis of a prospective cohort study. SETTING: Single large university medical intensive care unit. PATIENTS: A total of 4,684 consecutive admissions from January 1, 1994, to April 1, 1998, to the medical ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The independent influence of patient characteristics, including daily APS, admission diagnosis, treatment status, and admission location, on ICU readmission was evaluated using logistic regression. After accounting for first ICU admission deaths, 3,310 patients were "at-risk" for ICU readmission and 317 were readmitted (9.6%). Hospital mortality was five times higher (43% vs. 8%; p < .0001), and length of stay was two times longer (16 +/- 16 vs. 32 +/- 28 days; p < .001) in readmitted patients. Mean discharge APS was significantly higher in the readmitted group compared with the not readmitted group (43 +/- 19 vs. 34 +/- 18; p > .01). Significant independent predictors of ICU readmission included discharge APS >40 (odds ratio [OR] 2.1; 95% confidence interval [CI] 1.6-2.7; p < .0001), admission to the ICU from a general medicine ward (Floor) (OR 1.9; 95% CI 1.4-2.6; p < .0001), and transfer to the ICU from other hospital (Transfer) (OR 1.7; 95% CI 1.3-2.3; p < .01). The overall model calibration and discrimination were (H-L chi2 = 3.8, df = 8; p = .85) and (receiver operating characteristic 0.67), respectively. CONCLUSIONS: Patients readmitted to medical ICUs have significantly higher hospital lengths of stay and mortality. ICU readmissions may be more common among patients who respond poorly to treatment as measured by increased severity of illness at first ICU discharge and failure of prior therapy at another hospital or on a general medicine unit. Tertiary care ICUs may have higher than expected readmission rates and mortalities, even when accounting for severity of illness, if they care for significant numbers of transferred patients.