Altered hip muscle forces during gait in people with patellofemoral osteoarthritis

Objectives: The study aimed to (1) assess whether higher vasti (VASTI), gluteus medius (GMED), gluteus maximus (GMAX) and gluteus minimus (GMIN) forces are associated with participant characteristics (lower age, male gender) and clinical characteristics (lower radiographic disease severity, lower symptom severity and higher walking speed); and (2) determine whether hip and knee muscle forces are lower in people with patellofemoral joint (PFJ) osteoarthritis (OA) compared to those without PFJ OA. Design: Sixty participants with PFJ OA and 18 (asymptomatic, no radiographic OA) controls ≥40 years were recruited from the community or via referrals. A three-dimensional musculoskeletal model was used in conjunction with optimisation theory to calculate lower-limb muscle forces during walking. Associations of peak muscle forces with participant and clinical characteristics were conducted using Pearson's r or independent t-tests and between-group comparisons of mean peak muscle forces performed with walking speed as a covariate. Results: Peak muscle forces were not significantly associated with participant, symptomatic or radiographic-specific characteristics. Faster walking speed was associated with higher VASTI muscle force in the PFJ OA (r = 0.495; P < 0.001) and control groups (r = 0.727; P = 0.001) and higher GMAX muscle force (r = 0.593; P = 0.009) in the control group only. Individuals with PFJ OA (N = 60) walked with lower GMED and GMIN muscle forces than controls (N = 18): GMED, mean difference 0.15 [95% confidence interval (CI): 0.01 to 0.29] body weight (BW); GMIN, 0.03 [0.01 to 0.06] BW. No between-group differences were observed in VASTI or GMAX muscle force: VASTI, 0.10 [-0.11 to 0.31] BW; GMAX, 0.01 [-0.11 to 0.09] BW. Conclusion: Individuals with PFJ OA ambulate with lower peak hip abductor muscle forces than their healthy counterparts

Employers' and Employees' Understanding of Occupational Health and Safety Risks in Small Businesses: A Case Study

Many small businesses have hazardous work environments and exposures to significant occupational health and safety risks. Differences in understanding of risks by employers and employees are one of the factors leading to the hazardous work environment and risk exposures in small businesses. Employees generally describe “the tools of the trade” as the sources of risks of accidents and injuries, whereas employers generally identify “bad employees” or “bad luck” as the cause of accidents. It seems that employer and employees having the same or a shared understanding of occupational health and safety problems, their causal relations and the course of action is essential to remedy the work environment problems in the workplace. This paper describes a study that explores owner/managers’ and employees’ understandings of occupational health and safety risks in small business workplaces within the framework of the Local Theory of Work Environment. A case study of an independently operated restaurant and café in New Zealand employing 6­19 employees was undertaken.. Data was collected using participant­as­observer ethnographic observation of the workplace followed by semi structured interviews of the owner, a manager and more than fifty per cent of employees employed in the business. Preliminary findings based on interview data are reported in this paper. The results suggest that the owner/manager and employees mainly consider physical safety problems experienced by employees or food safety problems affecting the customers as the key work environment problems. The owner/manager and employees generally link common sense and breach of norms with the causal relation behind these problems. Social exchange and external certification, among others, are found to be prominent reasons for bringing to attention the perceived problems in the wider work environment context. Implicit individual element of action and explicit organizational element of action are recognised as the two courses of action remedying the occupational health and safety problems. Further studies can be directed at finding how a shared understanding of the OHS risks occurs and what influences this process

The effects of a varus unloader brace for lateral tibiofemoral osteoarthritis and valgus malalignment after anterior cruciate ligament reconstruction: A single case study

We investigated the immediate effects of a varus knee brace on knee symptoms and knee-joint biomechanics in an individual with predominant lateral tibiofemoral joint osteoarthritis (TFJOA) and valgus malalignment after anterior cruciate ligament (ACL) reconstruction. A varus unloader brace was prescribed to a 48-year-old male with predominant lateral radiographic and symptomatic TFJOA and valgus malalignment eight-years following ACL reconstruction. During a step-down task, the participant rated knee pain, task-difficulty, knee-stability and knee-confidence on four separate visual analogue scales. Quantitative gait analysis was conducted during self-selected walking trials under three test conditions in a randomized order: (i) no brace; (ii) brace without frontal plane adjustment (no varus re-alignment); and (ii) brace with frontal plane adjustment (varus re-alignment). Post-processing of gait data involved calculation of knee kinematics and net joint moments for the reconstructed limb. The participant reported improved pain (3%), task difficulty (41%), stability (46%) and confidence (49%) when performing the step-down task with the brace. The varus brace resulted in immediate reductions in knee abduction angle (24%) and internal rotation angle (56%), and increased knee adduction moment (18%). These findings provide preliminary evidence for potentially beneficial effects of bracing on knee-symptoms and biomechanics in individuals with lateral TFJOA after reconstruction

Large-Scale Numerical Modeling of Melt and Solution Crystal Growth

We present an overview of mathematical models and their large-scale numerical solution for simulating different phenomena and scales in melt and solution crystal growth. Samples of both classical analyses and state-of-the-art computations are presented. It is argued that the fundamental multi-scale nature of crystal growth precludes any one approach for modeling, rather successful crystal growth modeling relies on an artful blend of rigor and practicality

Variability of walking in able-bodied adults across different time intervals

This study aimed to quantify the variability of walking in young adults across measurement sessions held at varied time intervals. Inconsistent marker placement, a major source of variation in gait measurement, was minimized in this study in order to quantify how much variation is attributable to participants naturally altering their walking. Three-dimensional gait data were captured from five young adults on four sessions on each of four days. After Day 1, marker locations were identified with permanent pen to minimise variance due to inconsistent marker placement. A multi-level linear regression model was used to estimate intertrial and inter-session variance for two hour, within-day, across-a-day and across-a-week intervals. Inter-trial variation was relatively constant within sessions and ranged from a standard deviation (SD) of 0.7 degrees to 2.5 degrees. Inter-session variation differed across gait variables and time intervals, with a maximum variation of 2.4 degrees (hip rotation, across a week). Young adults varied their kinematic walking patterns (SD = 1-2 degrees) over intervals of 2 hours to 1 week. In reliability studies, variations of this magnitude may simply reflect natural or ‘intrinsic’ human variation rather than marker placement error

Physical activity when young provides lifelong benefits to cortical bone size and strength in men

The skeleton shows greatest plasticity to physical activity-related mechanical loads during youth but is more at risk for failure during aging. Do the skeletal benefits of physical activity during youth persist with aging? To address this question, we used a uniquely controlled cross-sectional study design in which we compared the throwing-to-nonthrowing arm differences in humeral diaphysis bone properties in professional baseball players at different stages of their careers (n = 103) with dominant-to-nondominant arm differences in controls (n = 94). Throwing-related physical activity introduced extreme loading to the humeral diaphysis and nearly doubled its strength. Once throwing activities ceased, the cortical bone mass, area, and thickness benefits of physical activity during youth were gradually lost because of greater medullary expansion and cortical trabecularization. However, half of the bone size (total cross-sectional area) and one-third of the bone strength (polar moment of inertia) benefits of throwing-related physical activity during youth were maintained lifelong. In players who continued throwing during aging, some cortical bone mass and more strength benefits of the physical activity during youth were maintained as a result of less medullary expansion and cortical trabecularization. These data indicate that the old adage of “use it or lose it” is not entirely applicable to the skeleton and that physical activity during youth should be encouraged for lifelong bone health, with the focus being optimization of bone size and strength rather than the current paradigm of increasing mass. The data also indicate that physical activity should be encouraged during aging to reduce skeletal structural decay

Employers' and Employees' Understanding of Occupational Health and Safety Risks in Small Businesses: A Case Study

Many small businesses have hazardous work environments and exposures to significant occupational health and safety risks. Differences in understanding of risks by employers and employees are one of the factors leading to the hazardous work environment and risk exposures in small businesses. Employees generally describe “the tools of the trade” as the sources of risks of accidents and injuries, whereas employers generally identify “bad employees” or “bad luck” as the cause of accidents. It seems that employer and employees having the same or a shared understanding of occupational health and safety problems, their causal relations and the course of action is essential to remedy the work environment problems in the workplace. This paper describes a study that explores owner/managers’ and employees’ understandings of occupational health and safety risks in small business workplaces within the framework of the Local Theory of Work Environment. A case study of an independently operated restaurant and café in New Zealand employing 6­19 employees was undertaken.. Data was collected using participant­as­observer ethnographic observation of the workplace followed by semi structured interviews of the owner, a manager and more than fifty per cent of employees employed in the business. Preliminary findings based on interview data are reported in this paper. The results suggest that the owner/manager and employees mainly consider physical safety problems experienced by employees or food safety problems affecting the customers as the key work environment problems. The owner/manager and employees generally link common sense and breach of norms with the causal relation behind these problems. Social exchange and external certification, among others, are found to be prominent reasons for bringing to attention the perceived problems in the wider work environment context. Implicit individual element of action and explicit organizational element of action are recognised as the two courses of action remedying the occupational health and safety problems. Further studies can be directed at finding how a shared understanding of the OHS risks occurs and what influences this process

Exercise, education, manual-therapy and taping compared to education for patellofemoral osteoarthritis: a blinded, randomised clinical trial

Objective: Patellofemoral joint osteoarthritis (PFJ OA) contributes considerably to knee OA symptoms. This study aimed to determine the efficacy of a PFJ-targeted exercise, education manual-therapy and taping program compared to OA education alone, in participants with PFJ OA. Methods: A randomised, participant-blinded and assessor-blinded clinical trial was conducted in primary-care physiotherapy. 92 people aged ≥40 years with symptomatic and radiographic PFJ OA participated. Physiotherapists delivered the PFJ-targeted exercise, education, manual-therapy and taping program, or the OA-education (control condition) in eight sessions over 12 weeks.Primary outcomes at 3-month (primary) and 9-month follow-up: (1) patient-perceived global rating of change (2) pain visual analogue scale (VAS) (100 mm); and (3) activities of daily living (ADL) subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: 81 people (88%) completed the 3-month follow-up and data analysed on an intention-to-treat basis. Between-group baseline similarity for participant characteristics was observed. The exercise, education, manual-therapy and taping program resulted in more people reporting much improvement (20/44) than the OA-education group (5/48) (number needed to treat 3 (95% confidence interval (CI) 2 to 5)) and greater pain reduction (mean difference: -15.2 mm, 95% CI -27.0 to -3.4). No significant effects on ADL were observed (5.8; 95% CI -0.6 to 12.1). At 9 months there were no significant effects for self-report of improvement, pain (-10.5 mm, 95% CI -22.7 to 1.8) or ADL (3.0, 95% CI -3.7 to 9.7). Conclusion: Exercise, education, manual-therapy and taping can be recommended to improve short-term patient rating of change and pain severity. However over 9-months, both options were equivalent. Trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12608000288325): https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=82878

Standardization proposal of soft tissue artefact description for data sharing in human motion measurements

Soft tissue artefact (STA) represents one of the main obstacles for obtaining accurate and reliable skeletal kinematics from motion capture. Many studies have addressed this issue, yet there is no consensus on the best available bone pose estimator and the expected errors associated with relevant results. Furthermore, results obtained by different authors are difficult to compare due to the high variability and specificity of the phenomenon and the different metrics used to represent these data. Therefore, the aim of this study was twofold: firstly, to propose standards for description of STA; and secondly, to provide illustrative STA data samples for body segments in the upper and lower extremities and for a range of motor tasks specifically, level walking, stair ascent, sit-to-stand, hip- and knee-joint functional movements, cutting motion, running, hopping, arm elevation and functional upper-limb movements. The STA dataset includes motion of the skin markers measured in vivo and ex vivo using stereophotogrammetry as well as motion of the underlying bones measured using invasive or bio-imaging techniques (i.e., X-ray fluoroscopy or MRI). The data are accompanied by a detailed description of the methods used for their acquisition, with information given about their quality as well as characterization of the STA using the proposed standards. The availability of open-access and standard-format STA data will be useful for the evaluation and development of bone pose estimators thus contributing to the advancement of three-dimensional human movement analysis and its translation into the clinical practice and other applications