Retention of kinematic patterns during a 6-minute walk test in people with knee osteoarthritis

Background: Knee osteoarthritis (OA) is a chronic condition affecting the entire joint and surrounding tissue, resulting in pain, stiffness and impaired movement. Recent studies have suggested the use of physical performance tests, such as the six-minute walk test (6MWT) to assess joint function for those with knee OA. This study assessed lower limb sagittal plane joint angles during a 6MWT for people with mild-moderate knee OA. Methods: Thirty-one participants (18 male, 13 female; 62.9 ± 8.4 years) with knee OA were recruited. Gait data were collected in a single session during which participants completed a 6MWT around a 20 m course. Sagittal plane joint angles for the hip, knee and ankle were calculated during the first and last minute of the 6MWT. Statistical parametric mapping (SPM) was used to investigate changes in kinematic traces over the gait cycle. Results: Mean joint angles for the hip and knee showed no significant differences between the first and last minute of the 6MWT. Ankle joint kinematic traces indicated there to be a decrease in plantarflexion approaching toe-off in the last minute of the test – a 1.5◦ reduction from the first minute. No significant differences were calculated for walking speed or joint range of motion. Discussion: The lack of significant change in joint kinematic parameters and walking speed suggests the relative fatigue and pain burden to the participant over the duration of the 6-minute period is insufficient to elicit any mechanical changes to walking gait.Stuart C. Millar, Kieran Bennett, Mark Rickman, Dominic Thewli

The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial

INTRODUCTION: The outcome of the effects of transitioning to minimalist running shoes is a topic of interest for runners and scientists. However, few studies have investigated the longer term effects of running in minimalist shoes. The purpose of this randomised controlled trial (RCT) is to investigate the effects of a 26 week transition to minimalist shoes on running performance and injury risk in trained runners unaccustomed to minimalist footwear. METHODS AND ANALYSIS: A randomised parallel intervention design will be used. Seventy-six trained male runners will be recruited. To be eligible, runners must be aged 18-40 years, run with a habitual rearfoot footfall pattern, train with conventional shoes and have no prior experience with minimalist shoes. Runners will complete a standardised transition to either minimalist or control shoes and undergo assessments at baseline, 6 and 26 weeks. 5 km time-trial performance (5TT), running economy, running biomechanics, triceps surae muscle strength and lower limb bone mineral density will be assessed at each time point. Pain and injury will be recorded weekly. Training will be standardised during the first 6 weeks. Primary statistical analysis will compare 5TT between shoe groups at the 6-week time point and injury incidence across the entire 26-week study period. ETHICS AND DISSEMINATION: This RCT has been approved by the Human Research Ethics Committee of the University of South Australia. Participants will be required to provide their written informed consent prior to participation in the study. Study findings will be disseminated in the form of journal publications and conference presentations after completion of planned data analysis. TRIAL REGISTRATION NUMBER: This RCT has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12613000642785).Joel T Fuller, Dominic Thewlis, Margarita D Tsiros, Nicholas A T Brown, Jonathan D Buckle

Proximal Femoral Nail Unlocked versus Locked (ProFNUL): a protocol for a multicentre, parallel-armed randomised controlled trial for the effect of femoral nail mode of lag screw locking and screw configuration in the treatment of intertrochanteric femur fractures

Introduction: Intertrochanteric fractures are common fragility injuries in the elderly. Surgical fixation using intramedullary devices are one of the widely used management options. To date, evidence demonstrating the effects of lag screw configuration and the mode of lag screw locking in these devices is lacking. The purpose of this study is to investigate whether the lag screw configuration (single vs integrated dual interlocking screw) and the mode of lag screw locking (static vs dynamic) of a femoral nail device result in differences in clinical and functional outcomes. Methods and Analysis: A multicentre, pragmatic, single-blinded randomised controlled trial (RCT) with a three-arm parallel group design is proposed. Nine-hundred patients with intertrochanteric fractures (A1 and A2 AO/OTA) will be randomised to fracture treatment using a Gamma3 nail (Stryker; proximally dynamic) or a Trigen Intertan nail (Smith & Nephew) in a dynamic or static lag screw configuration. The primary outcome measure consists of radiological evidence of construct failure within 6 months following surgery, with failure being defined as breakage of the femoral nail or distal locking screw, a change in tip-apex distance of more than 10 mm or lag screw cut-out through the femoral head. Secondary outcomes include surgical data (operation time, fluoroscopy time), complications (surgical site infection, reoperation, patient death), return to mobility and home circumstances, functional independence, function and pain. Patients who are able to walk independently with or without a mobility aid and are able to answer simple questions and follow instructions will be asked to participate in three dimensional gait analysis at 6 weeks and 6 months to assess hip biomechanics from this cohort. Additional secondary measures of gait speed, hip range of motion, joint contact and muscle forces and gross activity monitoring patterns will be obtained in this subgroup. Ethics and Dissemination: The Central Adelaide Local Health Network Human Research Ethics Committee has approved the protocol for this RCT (HREC/17/RAH/433). The results will be disseminated via peer-reviewed publications and presentations at relevant conferences.Arjun Sivakumar, Dominic Thewlis, Andreas Ladurner, Suzanne Edwards, Mark Rickma

The effect of surgical change to hip geometry on hip biomechanics after primary total hip arthroplasty

First published: 06 October 2022. OnlinePublThe aim of this study was to determine the effect of surgical change to the acetabular offset and femoral offset on the abductor muscle and hip contact forces after primary THA using computational methods. Thirty-five patients undergoing primary THA were recruited. Patients underwent a computed tomography scan of their pelvis and hip, and underwent gait analysis pre- and 6-months post-operatively. Surgically induced changes in acetabular and femoral offset were used to inform a musculoskeletal model to estimated abductor muscle and hip joint contact forces. Two experiments were performed: (1) influence of changes in hip geometry on hip biomechanics with preoperative kinematics; and (2) influence of changes in hip geometry on hip biomechanics with postoperative kinematics. Superior and medial placement of the hip centre of rotation during THA was most influential in reducing hip contact forces, predicting 63% of the variance (p<0.001). When comparing the preoperative geometry and kinematics model, with postoperative geometry and kinematics, hip contact forces increased after surgery (0.68 BW, p=0.001). Increasing the abductor lever arm reduced abductor muscle force by 28% (p<0.001) and resultant hip contact force by 17% (0.6 BW, p=0.003), with both preoperative and postoperative kinematics. Failure to increase abductor lever arm increased resultant hip contact force 11% (0.33 BW, p<0.001). In conclusion, increasing the abductor lever arm provides a substantial biomechanical benefit to reduce hip abductor and resultant hip joint contact forces. The magnitude of this effect is equivalent to the average increase in hip contact force seen with improved gait from pre-to post-surgery. This article is protected by copyright. All rights reserved.Jasvir S. Bahl, John B. Arnold, David J. Saxby, Mark Taylor, Lucian B. Solomon, Dominic Thewli

Quantifying the in vivo quasi-static response to loading of sub-dermal tissues in the human buttock using magnetic resonance imaging

This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 12 month embargo from date of publication (Oct 2017) in accordance with the publisher’s archiving policyBackground The design of seating systems to improve comfort and reduce injury would benefit from improved understanding of the deformation and strain patterns in soft tissues, particularly in the gluteal region. Methods Ten healthy men were positioned in a semi-recumbent posture while their pelvic and thigh region was scanned using a wide-bore magnetic resonance imaging (MRI) scanner. Independent measurements of deformation for muscles and fat were taken for the transition from non-weight-bearing to weight-bearing loads in three stages. A weight-bearing load was achieved through having the subject supported by a flat, rigid surface. A non-weight-bearing condition was achieved by removing the support under the left buttock, leaving all soft tissue layers undeformed. An intermediate condition partially relieved the subject's left buttock by lowering the support relative to the pelvis by 20 mm, which left the buttock partially deformed. For each of these conditions, the thicknesses of muscle and fat tissues below the ischial tuberosity and the greater trochanter were measured from the MRI data. Findings In this dataset, the greatest soft tissue deformation took place below the ischial tuberosity, with muscles (mean = 17.7 mm, SD = 4.8 mm) deforming more than fat tissues (mean = 4.3 mm, SD = 5.6 mm). Muscles deformed through both steps of the transition from weight-bearing to non-weight-bearing conditions, while subcutaneous fat deformed little after the first transition from non-weight-bearing to partial-weight-bearing. High inter-subject variability in muscle and fat tissue strains was observed. Interpretation Our findings highlight the importance of considering inter-subject variability when designing seating systems

Viable Influenza A Virus in Airborne Particles Expelled During Coughs Versus Exhalations

Background To prepare for a possible influenza pandemic, a better understanding of the potential for the airborne transmission of influenza from person to person is needed. Objectives The objective of this study was to directly compare the generation of aerosol particles containing viable influenza virus during coughs and exhalations. Methods Sixty-one adult volunteer outpatients with influenza-like symptoms were asked to cough and exhale three times into a spirometer. Aerosol particles produced during coughing and exhalation were collected into liquid media using aerosol samplers.The samples were tested for the presence of viable influenza virus using a viral replication assay (VRA). Results Fifty-three test subjects tested positive for influenza A virus. Of these, 28 (53%) produced aerosol particles containing viable influenza A virus during coughing, and 22 (42%) produced aerosols with viable virus during exhalation. Thirteen subjects had both cough aerosol and exhalation aerosol samples that contained viable virus, 15 had positive cough aerosol samples but negative exhalation samples, and 9 had positive exhalation samples but negative cough samples. Conclusions Viable influenza A virus was detected more often in cough aerosol particles than in exhalation aerosol particles, but the difference was not large. Because individuals breathe much more often than they cough, these results suggest that breathing may generate more airborne infectious material than coughing over time. However, both respiratory activities could be important in airborne influenza transmission. Our results are also consistent with the theory that much of the aerosol containing viable influenza originates deep in the lung

Measurements of Airborne Influenza Virus in Aerosol Particles from Human Coughs

Influenza is thought to be communicated from person to person by multiple pathways. However, the relative importance of different routes of influenza transmission is unclear. To better understand the potential for the airborne spread of influenza, we measured the amount and size of aerosol particles containing influenza virus that were produced by coughing. Subjects were recruited from patients presenting at a student health clinic with influenza-like symptoms. Nasopharyngeal swabs were collected from the volunteers and they were asked to cough three times into a spirometer. After each cough, the cough-generated aerosol was collected using a NIOSH two-stage bioaerosol cyclone sampler or an SKC BioSampler. The amount of influenza viral RNA contained in the samplers was analyzed using quantitative real-time reverse-transcription PCR (qPCR) targeting the matrix gene M1. For half of the subjects, viral plaque assays were performed on the nasopharyngeal swabs and cough aerosol samples to determine if viable virus was present. Fifty-eight subjects were tested, of whom 47 were positive for influenza virus by qPCR. Influenza viral RNA was detected in coughs from 38 of these subjects (81%). Thirty-five percent of the influenza RNA was contained in particles \u3e4 µm in aerodynamic diameter, while 23% was in particles 1 to 4 µm and 42% in particles \u3c1 µm. Viable influenza virus was detected in the cough aerosols from 2 of 21 subjects with influenza. These results show that coughing by influenza patients emits aerosol particles containing influenza virus and that much of the viral RNA is contained within particles in the respirable size range. The results support the idea that the airborne route may be a pathway for influenza transmission, especially in the immediate vicinity of an influenza patient. Further research is needed on the viability of airborne influenza viruses and the risk of transmission

Magnetoelectric ordering of BiFeO3 from the perspective of crystal chemistry

In this paper we examine the role of crystal chemistry factors in creating conditions for formation of magnetoelectric ordering in BiFeO3. It is generally accepted that the main reason of the ferroelectric distortion in BiFeO3 is concerned with a stereochemical activity of the Bi lone pair. However, the lone pair is stereochemically active in the paraelectric orthorhombic beta-phase as well. We demonstrate that a crucial role in emerging of phase transitions of the metal-insulator, paraelectric-ferroelectric and magnetic disorder-order types belongs to the change of the degree of the lone pair stereochemical activity - its consecutive increase with the temperature decrease. Using the structural data, we calculated the sign and strength of magnetic couplings in BiFeO3 in the range from 945 C down to 25 C and found the couplings, which undergo the antiferromagnetic-ferromagnetic transition with the temperature decrease and give rise to the antiferromagnetic ordering and its delay in regard to temperature, as compared to the ferroelectric ordering. We discuss the reasons of emerging of the spatially modulated spin structure and its suppression by doping with La3+.Comment: 18 pages, 5 figures, 3 table

Vibrational properties of the one-component σ\sigma phase

A structural model of a one-component $\sigma$-phase crystal has been constructed by means of molecular dynamics simulation. The phonon dispersion curves and the vibrational density of states were computed for this model. The dependence of the vibrational properties on the thermodynamical parameters was investigated. The vibrational density of states of the $\sigma$-phase structure is found to be similar to that of a one-component glass with icosahedral local order. On the basis of this comparison it is concluded that the $\sigma$ phase can be considered to be a good crystalline reference structure for this glass