Childhood-Onset Lupus Nephritis in the Childhood Arthritis and Rheumatology Research Alliance Registry: Short-Term Kidney Status and Variation in Care

OBJECTIVE

The goal was to characterize short-term kidney status and describe variation in early care utilization in a multicenter cohort of patients with childhood-onset systemic lupus erythematosus (cSLE) and nephritis.

METHODS

We analyzed previously collected prospective data from North American patients with cSLE with kidney biopsy-proven nephritis enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry from March 2017 through December 2019. We determined the proportion of patients with abnormal kidney status at the most recent registry visit and applied generalized linear mixed models to identify associated factors. We also calculated frequency of medication use, both during induction and ever recorded.

RESULTS

We identified 222 patients with kidney biopsy-proven nephritis, with 64% class III/IV nephritis on initial biopsy. At the most recent registry visit at median (interquartile range) of 17 (8-29) months from initial kidney biopsy, 58 of 106 patients (55%) with available data had abnormal kidney status. This finding was associated with male sex (odds ratio [OR] 3.88, 95% confidence interval [95% CI] 1.21-12.46) and age at cSLE diagnosis (OR 1.23, 95% CI 1.01-1.49). Patients with class IV nephritis were more likely than class III to receive cyclophosphamide and rituximab during induction. There was substantial variation in mycophenolate, cyclophosphamide, and rituximab ever use patterns across rheumatology centers.

CONCLUSION

In this cohort with predominately class III/IV nephritis, male sex and older age at cSLE diagnosis were associated with abnormal short-term kidney status. We also observed substantial variation in contemporary medication use for pediatric lupus nephritis between pediatric rheumatology centers. Additional studies are needed to better understand the impact of this variation on long-term kidney outcomes.

Intraarticular steroids as DMARD-sparing agents for juvenile idiopathic arthritis flares: Analysis of the Childhood Arthritis and Rheumatology Research Alliance Registry

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) who achieve a drug free remission often experience a flare of their disease requiring either intraarticular steroids (IAS) or systemic treatment with disease modifying anti-rheumatic drugs (DMARDs). IAS offer an opportunity to recapture disease control and avoid exposure to side effects from systemic immunosuppression. We examined a cohort of patients treated with IAS after drug free remission and report the probability of restarting systemic treatment within 12 months.

METHODS

We analyzed a cohort of patients from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry who received IAS for a flare after a period of drug free remission. Historical factors and clinical characteristics and of the patients including data obtained at the time of treatment were analyzed.

RESULTS

We identified 46 patients who met the inclusion criteria. Of those with follow up data available 49% had restarted systemic treatment 6 months after IAS injection and 70% had restarted systemic treatment at 12 months. The proportion of patients with prior use of a biologic DMARD was the only factor that differed between patients who restarted systemic treatment those who did not, both at 6 months (79% vs 35%, p < 0.01) and 12 months (81% vs 33%, p < 0.05).

CONCLUSION

While IAS are an option for all patients who flare after drug free remission, it may not prevent the need to restart systemic treatment. Prior use of a biologic DMARD may predict lack of success for IAS. Those who previously received methotrexate only, on the other hand, are excellent candidates for IAS.

National audit of non-melanoma skin cancer excisions performed by plastic surgery in the UK

A national, multi-centre audit of non-melanoma skin cancer excisions by plastic surgery.

A comparison of the kinematics and kinetics of barefoot and shod running in children with cerebral palsy

BACKGROUND

The biomechanics of barefoot and shod running are different for typically developing children but unknown for children with cerebral palsy (CP). Such differences may have implications for injury and performance.

AIMS

The primary aims of this study were to compare the lower limb biomechanics of barefoot and shod running in children with CP, and to determine whether any differences were the same in GMFCS levels I and II.

METHODS

This cross-sectional study examined 38 children with CP (n = 24 (GMFCS) level I; n = 14 GMFCS II), running overground at 3 speeds (jog, run, sprint) in barefoot and shod conditions. Marker trajectories and force plate data were recorded, and lower limb kinematics, kinetics and spatiotemporal variables were derived. Differences between barefoot and shod running were analysed using linear mixed models.

RESULTS

For both GMFCS levels, barefoot running resulted in higher loading rates, but smaller impact peaks at all speeds. Barefoot running was associated with greater hip and knee power; less ankle dorsiflexion and hip flexion at initial contact, and less ankle and knee range of motion during stance, compared to shod running, at all speeds. Barefoot stride length was shortened, and cadence increased compared to shod during jogging and running but not sprinting. For GMFCS level I only, barefoot running involved a higher incidence of forefoot strike, greater ankle power generation and less hip range of motion during stance.

SIGNIFICANCE

Running barefoot may facilitate running performance by increasing power generation at the ankle in children with CP, GMFCS level I. Higher barefoot loading rates may have implications for performance and injury.

O-251 Defining the exclusive role of male genome integrity on conceptus development

Study question

To determine the effect of sperm DNA fragmentation on embryo development by ruling out a female factor component.

Summary answer

By utilizing healthy donor oocytes, it is possible to quantify the sole deleterious effect of sperm DNA fragmentation and explore the ooplasmic repair mechanism.

What is known already

In approximately 50% of couples with unexplained ART failure, a subtle male factor is present that is missed in a conventional semen analysis assessing concentration, motility, and morphology. Additional information on male gamete competence can be acquired by assessing Sperm Chromatin Fragmentation (SCF). Indeed, a fragmented male genome can give rise to poorly developing embryos, leading to impaired implantation, lower pregnancy, and higher miscarriage rates. It has been previously seen that an oocyte, according to its age, can repair the damaged DNA contributed by the male gamete.

Study design, size, duration

In last decade, 316 couples, who have an elevated SCF, underwent ICSI cycles and resulted in disappointing clinical outcomes. To exclude an eventual confounding female factor, couples who utilized donor oocytes were identified and clinical outcome was compared to a control. To measure the role of an impaired sperm genome and a concurrent oocyte repair mechanism, we compared clinical outcomes between cycles in the same couples who used their own and subsequently donor oocytes.

Participants/materials, setting, methods

We included 381 couples screened for SCF; 65 underwent ICSI cycles with donor oocytes; of these, 46 underwent a previous ICSI cycle with their own oocytes. Fertilization, implantation, clinical pregnancy, and delivery rates were compared between above-mentioned groups. A TUNEL assay was used to measure SCF (≥500 spermatozoa were assessed/sample at a 15% threshold). Paired t and Chi-square tests were used to compare ages and clinical outcomes, respectively.

Main results and the role of chance

We included 381 couples (maternal age, 37.8 ± 4.2; paternal age, 41.8 ± 8.2), whose male partners had the following semen parameters: average volume of 2.5 mL, concentration of 25.4x106/mL, 33% motility, and normal morphology of 1.7. Of these, 316 had elevated average DNA fragmentation of 25.5% and utilized their own oocytes in 683 ICSI cycles, resulting in a 67.5% fertilization, 12.2% implantation, 27.9% clinical pregnancy, and a 22.5% ongoing/delivery. Of the 381 couples, 65 underwent ICSI utilizing donor oocytes (SCF of 24.3%) resulting in a significantly higher fertilization (78.4%) (P &lt; 0.00001) and embryo implantation rates (34.2%) (P &lt; 0.0001). Similarly, albeit not statistically significant, the clinical pregnancy and ongoing/delivery rates increased from 27.9% to 37.1% and from 22.5% to 30.0%, respectively.

To further explore the exclusive role of the male gamete in embryo development, we identified a cohort of patients (n = 46), with an elevated average DNA fragmentation of 23.6%, who underwent an ICSI cycle using their own oocytes and a subsequent cycle using donor oocytes. Compared to cycles where couples used their own oocytes, fertilization, embryo implantation, clinical pregnancy, and ongoing/delivery rates rose from 67.5% to 76.6% (P &lt; 0.0001), 2.8% to 24.7% (P &lt; 0.00001), 8.4% to 38.8% (P &lt; 0.0001), and 1.2% to 28.6% (P &lt; 0.00001), respectively.

Limitations, reasons for caution

Although this study attempts to control for a concurrent confounding female factor, it cannot be completely excluded. It is difficult to assess the extent and contribution of the ooplasmic repair mechanisms on the male genome.

Wider implications of the findings

Ooplasmic repair mechanisms of healthy female gametes appear to repair or improve the deleterious impact of sperm DNA fragmentation on ART outcomes.

Trial registration number

not applicable

Social determinants of health influence disease activity and functional disability in Polyarticular Juvenile Idiopathic Arthritis

BACKGROUND

Social determinants of health (SDH) greatly influence outcomes during the first year of treatment in rheumatoid arthritis, a disease similar to polyarticular juvenile idiopathic arthritis (pJIA). We investigated the correlation of community poverty level and other SDH with the persistence of moderate to severe disease activity and functional disability over the first year of treatment in pJIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance Registry.

METHODS

In this cohort study, unadjusted and adjusted generalized linear mixed effects models analyzed the effect of community poverty and other SDH on disease activity, using the clinical Juvenile Arthritis Disease Activity Score-10, and disability, using the Child Health Assessment Questionnaire, measured at baseline, 6, and 12 months.

RESULTS

One thousand six hundred eighty-four patients were identified. High community poverty (≥20% living below the federal poverty level) was associated with increased odds of functional disability (OR 1.82, 95% CI 1.28-2.60) but was not statistically significant after adjustment (aOR 1.23, 95% CI 0.81-1.86) and was not associated with increased disease activity. Non-white race/ethnicity was associated with higher disease activity (aOR 2.48, 95% CI: 1.41-4.36). Lower self-reported household income was associated with higher disease activity and persistent functional disability. Public insurance (aOR 1.56, 95% CI 1.06-2.29) and low family education (aOR 1.89, 95% CI 1.14-3.12) was associated with persistent functional disability.

CONCLUSION

High community poverty level was associated with persistent functional disability in unadjusted analysis but not with persistent moderate to high disease activity. Race/ethnicity and other SDH were associated with persistent disease activity and functional disability.

eLearning in Physical Therapy: Lessons Learned From Transitioning a Professional Education Program to Full eLearning During the COVID-19 Pandemic

OBJECTIVE

The objectives of this cross-sectional qualitative study were to explore the perspectives of students enrolled in one physical therapist undergraduate education program in Australia about their experience with transitioning to full eLearning and student recommendations to improve the learning experience during the COVID-19 pandemic.

METHODS

Seven focus groups with 28 undergraduate physical therapist students were conducted following the transitioning to full eLearning as a result of strict physical distancing measures. Focus group questions explored the students' experiences of the transition from face-to-face to full eLearning approach and the students' recommendations for improving future eLearning experiences. Data were analyzed using inductive thematic analysis.

RESULTS

The 3 themes identified were: (1) students presenting heightened negative feelings such as anxiety, stress, and reduced motivation to study; (2) students continuing to value the face-to-face learning, as it provided social support and facilitated feedback from peers and tutors; (3) student recommendations for eLearning included having online lectures and supplementary videos but face-to-face practical classes and developing healthy learning habits such as scheduled times for studying, exercise, and other activities that regulate stress.

CONCLUSIONS

The transition to a full eLearning approach in an undergraduate physical therapist education program during the COVID-19 pandemic revealed that students had heightened negative emotions due to the pandemic. Students valued face-to-face practical classes to learn and receive social support from peers and tutors. Student recommendations to future eLearning suggested changes to curriculum development geared toward a greater blended approach to learning. Blended learning may include using online lectures instead of face-to-face lectures and online resources to supplement student learning of practical skills.

IMPACT

As higher education moves toward a more blended approach, lessons learned from this study can help educators design future physical therapist education programs. The findings can also assist programs in delivering a full eLearning approach as the COVID-19 pandemic continues.

Strategies for the use of Ginkgo biloba extract, EGb 761® , in the treatment and management of mild cognitive impairment in Asia: Expert consensus

BACKGROUND

Mild cognitive impairment (MCI) is a neurocognitive state between normal cognitive aging and dementia, with evidence of neuropsychological changes but insufficient functional decline to warrant a diagnosis of dementia. Individuals with MCI are at increased risk for progression to dementia; and an appreciable proportion display neuropsychiatric symptoms (NPS), also a known risk factor for dementia. Cerebrovascular disease (CVD) is thought to be an underdiagnosed contributor to MCI/dementia. The Ginkgo biloba extract, EGb 761® , is increasingly being used for the symptomatic treatment of cognitive disorders with/without CVD, due to its known neuroprotective effects and cerebrovascular benefits.

AIMS

To present consensus opinion from the ASian Clinical Expert group on Neurocognitive Disorders (ASCEND) regarding the role of EGb 761® in MCI.

MATERIALS & METHODS

The ASCEND Group reconvened in September 2019 to present and critically assess the current evidence on the general management of MCI, including the efficacy and safety of EGb 761® as a treatment option.

RESULTS

EGb 761® has demonstrated symptomatic improvement in at least four randomized trials, in terms of cognitive performance, memory, recall and recognition, attention and concentration, anxiety, and NPS. There is also evidence that EGb 761® may help delay progression from MCI to dementia in some individuals.

DISCUSSION

EGb 761® is currently recommended in multiple guidelines for the symptomatic treatment of MCI. Due to its beneficial effects on cerebrovascular blood flow, it is reasonable to expect that EGb 761® may benefit MCI patients with underlying CVD.

CONCLUSION

As an expert group, we suggest it is clinically appropriate to incorporate EGb 761® as part of the multidomain intervention for MCI.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

0365 Sleep Quality Associated with Perceived Stress and Autonomic Nervous System Measures: Implications for Sleep and Health Disparities

Introduction

It is not known whether the restorative nature of sleep mediates the effects of perceived stress on the autonomic nervous system (ANS).This study explored the relationships between stress and autonomic biomarkers, and aimed to assess potential mediation by sleep quality.

Methods

A secondary data analysis was performed using data from the Midlife in the United States (MIDUS, MIDUS II & Milwaukee). Multiple regression models examined the association between perceived stress using the Perceived Stress Scale (PSS) and two autonomic biomarkers-heart rate variability(HRV) (n=888) and urine catecholamines (n=1,058). The roles of sleep quality (using the Pittsburg Sleep Quality Index (PSQI)) and race/ethnicity were explored in post-hoc analyses.

Results

No statistically significant relationships were found between PSS and autonomic stress measures. However, perceived stress (b=0.09;p&lt;0.01; 95% CI=0.06,0.13) and the covariate Likert stress scale at baseline (b=0.13;p=&lt;0.04;95% CI=0.005,0.26) were significantly related to PSQI. Post hoc analyses explored racial differences. Baseline stress, PSS, depressive symptoms and PSQI scores were significantly higher in Blacks/African-Americans than Non-Hispanic Whites. Yet, Blacks/African-Americans had lower sympathetic responses (epinephrine means 1.56 vs 2.00;t=-4.82;p&lt;0.01, norepinephrine means, 24.15 vs 27.30;t=3.14;p&lt;0.01) and higher parasympathetic responses (lnHF, natural log of High Frequency HRV means 5.48 vs 4.75; t=6.17;p&lt;0.01), compared to Non-Hispanic Whites.

Conclusion

Blacks/African-Americans and Non-Hispanic Whites had significant differences in their sleep quality and ANS biomarkers. Sleep quality may play a role in the effect of discrimination on mental and physical health. Different stress sources may lead to variable expression in biomarkers of autonomic tone. Future prospective studies incorporating longitudinal biomarkers and alternative statistical models will help elucidate the relationships among stress, sleep, and the pathways linking these factors to poor health, and effect targeted treatments.

Support

The MIDUS I study was supported by the John D. and Catherine T. MacArthur Foundation Research Network. MIDUS II was supported by the NIA(P01-AG020166), M01-RR023942(Georgetown), M01-RR00865(UCLA) and 1UL1RR025011(UW) grants. Many thanks to Dr. James McNally, Dr. Barry Radler, Dr. Gayle Love and Suzanne Hodge for access to the Milwaukee dataset.

Cyanotic Congenital Heart Disease Modes of Presentation and Prenatal Detection

Prenatal detection of structural congenital heart disease (CHD) optimises cardiovascular stability pre-operatively and post-operative outcomes. We compared prenatal detection rates of critical CHD in units offering universal fetal anomaly scans with those offering imaging to selected women. One hundred and thirteen infants met inclusion criteria. The overall pre-natal detection rate for critical CHD was 57% of liveborn infants. It was 71% (57/80) in hospitals who offered a universal anomaly scan and 29% (9/31) in centres offering a limited service. Postnatal diagnosis was associated with PICU admission (p=0.016) and preoperative mechanical ventilation (p=0.001). One-year mortality was 10 fold higher in the postnatally diagnosed group 15% vs 1.55% (p=0.0066). There is a significant disparity between centres offering universal anomaly versus selective screening. Prenatal detection confers advantage in terms of pre-operative stability and one year survival. Failure to deliver an equitable service exposes infants with CHD to avoidable risk.

First Measurement of Near-Threshold J/ψ Exclusive Photoproduction off the Proton

We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8  GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39  GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Posttraumatic stress disorder in the World Mental Health Surveys

BACKGROUND

Traumatic events are common globally; however, comprehensive population-based cross-national data on the epidemiology of posttraumatic stress disorder (PTSD), the paradigmatic trauma-related mental disorder, are lacking.

METHODS

Data were analyzed from 26 population surveys in the World Health Organization World Mental Health Surveys. A total of 71 083 respondents ages 18+ participated. The Composite International Diagnostic Interview assessed exposure to traumatic events as well as 30-day, 12-month, and lifetime PTSD. Respondents were also assessed for treatment in the 12 months preceding the survey. Age of onset distributions were examined by country income level. Associations of PTSD were examined with country income, world region, and respondent demographics.

RESULTS

The cross-national lifetime prevalence of PTSD was 3.9% in the total sample and 5.6% among the trauma exposed. Half of respondents with PTSD reported persistent symptoms. Treatment seeking in high-income countries (53.5%) was roughly double that in low-lower middle income (22.8%) and upper-middle income (28.7%) countries. Social disadvantage, including younger age, female sex, being unmarried, being less educated, having lower household income, and being unemployed, was associated with increased risk of lifetime PTSD among the trauma exposed.

CONCLUSIONS

PTSD is prevalent cross-nationally, with half of all global cases being persistent. Only half of those with severe PTSD report receiving any treatment and only a minority receive specialty mental health care. Striking disparities in PTSD treatment exist by country income level. Increasing access to effective treatment, especially in low- and middle-income countries, remains critical for reducing the population burden of PTSD.

The timecourse of apoptotic cell death during postnatal remodeling of the mouse cochlea and its premature onset by triiodothyronine (T3)

Apoptosis underlies various forms of tissue remodeling during development. Prior to the onset of hearing, thyroid hormone (T3) promotes cochlear remodeling, which involves regression of the greater epithelial ridge (GER), a transient structure of columnar cells adjacent to the mechanosensory hair cells. We investigated the timecourse of apoptosis in the GER and the influence of ectopic T3 on apoptosis. In saline-treated mice, activated caspase 3-positive cells were detected in the GER between postnatal days 7 and 13 and appeared progressively along the cochlear duct from base to apex over developmental time. T3 given on P0 and P1 advanced the overall program of apoptosis and remodeling by ~4 days. Thyroid hormone receptor β was required for these actions, suggesting a receptor-mediated process of initiation of apoptosis. Finally, T3 given only at P0 or P1 resulted in deafness in adult mice, thus revealing a transient period of susceptibility to long-term damage in the neonatal auditory system.

Effect of Mulligan's and Kinesio knee taping on adolescent ballet dancers knee and hip biomechanics during landing

Taping is often used to manage the high rate of knee injuries in ballet dancers; however, little is known about the effect of taping on lower-limb biomechanics during ballet landings in the turnout position. This study investigated the effects of Kinesiotape (KT), Mulligan's tape (MT) and no tape (NT) on knee and hip kinetics during landing in three turnout positions. The effect of taping on the esthetic execution of ballet jumps was also assessed. Eighteen pain-free 12-15-year-old female ballet dancers performed ballet jumps in three turnout positions, under the three knee taping conditions. A Vicon Motion Analysis system (Vicon Oxford, Oxford, UK) and Advanced Mechanical Technology, Inc. (Watertown, Massa chusetts, USA) force plate collected lower-limb mechanics. The results demonstrated that MT significantly reduced peak posterior knee shear forces (P = 0.025) and peak posterior (P = 0.005), medial (P = 0.022) and lateral (P = 0.014) hip shear forces compared with NT when landing in first position. KT had no effect on knee or hip forces. No significant differences existed between taping conditions in all landing positions for the esthetic measures. MT was able to reduce knee and the hip forces without affecting the esthetic performance of ballet jumps, which may have implications for preventing and managing knee injuries in ballet dancers.

A radiological comparison of anterior fusion rates in anterior lumbar interbody fusion

Aim To compare anterior fusion in standalone anterior lumbar interbody fusion (ALIF) using cage and screw constructs and anterior cage-alone constructs with posterior pedicle screw supplementation but without posterior fusion. Methods Eighty-five patients underwent single- or two-level ALIF procedure for degenerative disk disease or lytic spondylolisthesis (SPL). Posterior instrumentation was performed without posterior fusion in all cases of lytic SPL and when the anterior cage used did not have anterior screw through cage fixation. Results Seventy (82%) patients had adequate radiological follow-up at a mean of 19 months. Forty patients had anterior surgery alone (24 single level and 16 two levels) and 30 had front-back surgery (15 single level and 15 two levels). Anterior locked pseudarthrosis was only seen in the anterior surgery-alone group when using the STALIF cage (Surgicraft, Worcestershire, UK) (37 patients). This occurred in five of the single-level surgeries (5/22) and nine of the two-level surgeries (9/15). Fusion was achieved in 100% of the front-back group and only 65% (26/40) of the anterior surgery-alone group. Conclusion Posterior pedicle screw supplementation without posterolateral fusion improves the fusion rate of ALIF when using anterior cage and screw constructs. We would recommend supplementary posterior fixation especially in cases where more than one level is being operated.

Generalization of a model based on biophysical concepts of muscle activation, fatigue and recovery that explains exercise performance

To address the limitations of regression-based performance models, the literature describes a fatigue model that reduces the complexities of motor unit activation into a set of first-order differential equations requiring only a few parameters to capture the global effects of activation physiology (M0: maximal force-generating capacity, F: fatigue rate, R: recovery rate). However, there are no solutions to the general form of the equations, which limits its applicability. We formulate an algorithm that allows the equations to be solved if an arbitrary force profile is specified. Furthermore, we support the validity of the model, applying it to exercises found in the literature including quadriceps contractions (M0=954±326 N, F=2.5±0.4%·s(-1), R=0.3±0.3%·s(-1)), cycling (M0=1095±486 W, F=3.5±0.3%·s(-1), R=1.1±0.3%·s(-1)) and running (M0=9.2±1.2 m·s(-1), F=0.9±0.4%·s(-1), R=1.0±0.3%·s(-1)), where effective muscle forces are converted to cycling power and running speed. The model predicts muscle output for 10 maximum efforts and 32 endurance tests, where the coefficient of determination (R2) ranged from 0.81 to 1.00. These results support the hypothesis found in the literature that motor unit activation and fatigue mechanisms lead to a cumulative muscle fatigue effect that can be observed in exercise performance.