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The human rotator cuff consists of four muscles, each with a complex, multipennate architecture. Despite the functional and clinical importance, the architecture of the human rotator cuff has yet to be clearly described in humans in vivo. The purpose of this study was to investigate the intramuscular, intermuscular, and interindividual variations in architecture and moment arms of the human rotator cuff. Muscle volumes, fascicle lengths, physiological cross‐sectional areas (PCSAs), pennation angles, and moment arms of all four rotator cuff muscles were measured from mDixon and diffusion tensor imaging (DTI) scans of the right shoulders of 20 young adults. In accordance with the most detailed dissections available to date, we found substantial intramuscular variation in fascicle length (coefficients of variation (CVs) ranged from 26% to 40%) and pennation angles (CVs ranged from 56% to 62%) in all rotator cuff muscles. We also found substantial intermuscular and interindividual variations in muscle volumes, but relatively consistent mean fascicle lengths, pennation angles, and moment arms (CVs for all ≤17%). Moreover, when expressed as a proportion of total rotator cuff muscle volume, the volumes of individual rotator cuff muscles were highly consistent between individuals and sexes (CVs ≤16%), suggesting that rotator cuff muscle volumes scale uniformly, at least in a younger population without musculoskeletal problems. Together, these data indicate limited interindividual and intermuscular variability in architecture, which may simplify scaling routines for musculoskeletal models. However, the substantial intramuscular variation in architecture questions the validity of previously reported mean architectural parameters to adequately describe rotator cuff function. [ABSTRACT FROM AUTHOR]

Muscle volume must increase substantially during childhood growth to generate the power required to propel the growing body. One unresolved but fundamental question about childhood muscle growth is whether muscles grow at equal rates; that is, if muscles grow in synchrony with each other. In this study, we used magnetic resonance imaging (MRI) and advances in artificial intelligence methods (deep learning) for medical image segmentation to investigate whether human lower leg muscles grow in synchrony. Muscle volumes were measured in 10 lower leg muscles in 208 typically developing children (eight infants aged less than 3 months and 200 children aged 5 to 15 years). We tested the hypothesis that human lower leg muscles grow synchronously by investigating whether the volume of individual lower leg muscles, expressed as a proportion of total lower leg muscle volume, remains constant with age. There were substantial age‐related changes in the relative volume of most muscles in both boys and girls (p < 0.001). This was most evident between birth and five years of age but was still evident after five years. The medial gastrocnemius and soleus muscles, the largest muscles in infancy, grew faster than other muscles in the first five years. The findings demonstrate that muscles in the human lower leg grow asynchronously. This finding may assist early detection of atypical growth and allow targeted muscle‐specific interventions to improve the quality of life, particularly for children with neuromotor conditions such as cerebral palsy. [ABSTRACT FROM AUTHOR]

Cerebral palsy is a neurological condition that is known to affect muscle growth. Detailed investigations of muscle growth require segmentation of muscles from MRI scans, which is typically done manually. In this study, we evaluated the performance of 2D, 3D, and hybrid deep learning models for automatic segmentation of 11 lower leg muscles and two bones from MRI scans of children with and without cerebral palsy. All six models were trained and evaluated on manually segmented T1‐weighted MRI scans of the lower legs of 20 children, six of whom had cerebral palsy. The segmentation results were assessed using the median Dice similarity coefficient (DSC), average symmetric surface distance (ASSD), and volume error (VError) of all 13 labels of every scan. The best performance was achieved by H‐DenseUNet, a hybrid model (DSC 0.90, ASSD 0.5 mm, and VError 2.6 cm3). The performance was equivalent to the inter‐rater performance of manual segmentation (DSC 0.89, ASSD 0.6 mm, and VError 3.3 cm3). Models trained with the Dice loss function outperformed models trained with the cross‐entropy loss function. Near‐optimal performance could be attained using only 11 scans for training. Segmentation performance was similar for scans of typically developing children (DSC 0.90, ASSD 0.5 mm, and VError 2.8 cm3) and children with cerebral palsy (DSC 0.85, ASSD 0.6 mm, and VError 2.4 cm3). These findings demonstrate the feasibility of fully automatic segmentation of individual muscles and bones from MRI scans of children with and without cerebral palsy. [ABSTRACT FROM AUTHOR]

Background and Purpose: PEDro (the Physiotherapy Evidence Database) is a widely used, comprehensive, freely available, online database that indexes studies of the effectiveness of physiotherapy interventions. We have recently built another database, called DiTA, on the same platform as PEDro. DiTA provides a comprehensive index of studies of the accuracy of diagnostic tests used by physiotherapists. This study aims to describe the number and scope of such studies. Methods: A comprehensive search was conducted for studies of the accuracy of diagnostic tests. The search was conducted on the MEDLINE, EMBASE and CINAHL databases from their inceptions to November 2018. Subsequently, monthly searches have updated the database. To be included on DiTA, studies need to investigate (a) both a pathology and patients that a physiotherapist could assess in clinical practice, and (b) an index test that a physiotherapist would perform themselves rather than one which they would request. Results: To date, the searches have yielded 44,884 titles. Screening has identified 1,419 reports that meet the inclusion criteria. The most frequently studied subdisciplines are "musculoskeletal" (1,050/1,419; 74.0%) and "cardiothoracics" (241; 17.0%); the most frequently studied categories of pathologies are joint pathologies (463; 32.6%) and nervous system pathologies (175; 12.3%); and the most frequently studied body part is the "lower leg or knee" (232; 16.3%). Most studies investigate index tests which are "physical examination" procedures (851; 60.0%); fewer investigate "questions or questionnaires" (420; 29.6%) and "health technologies" (351; 24.7%). Discussion: There is a rapidly growing body of evidence on the accuracy of diagnostic tests relevant to most physiotherapy subdisciplines. While the volume of evidence is substantial, it is not yet clear how much of the evidence is of good enough quality to support clinical decision‐making. [ABSTRACT FROM AUTHOR]

Muscle performance is closely related to the structure and function of tendons and aponeuroses, the sheet‐like, intramuscular parts of tendons. The architecture of aponeuroses has been difficult to study with magnetic resonance imaging (MRI) because these thin, collagen‐rich connective tissues have very short transverse relaxation (T2) times and therefore provide a weak signal with conventional MRI sequences. Here, we validated measurements of aponeurosis dimensions from two MRI sequences commonly used in muscle‐tendon research (mDixon and T1‐weighted images), and an ultrashort echo time (UTE) sequence designed for imaging tissues with short T2 times. MRI‐based measurements of aponeurosis width, length, and area of 20 sheep leg muscles were compared to direct measurements made with three‐dimensional (3D) quantitative microdissection. The errors in measurement of aponeurosis width relative to the mean width were 1.8% for UTE, 3.7% for T1, and 18.8% for mDixon. For aponeurosis length, the errors were 7.6% for UTE, 1.9% for T1, and 21.0% for mDixon. Measurements from T1 and UTE scans were unbiased, but mDixon scans systematically underestimated widths, lengths, and areas of the aponeuroses. Using the same methods, we then found high inter‐rater reliability (intraclass correlation coefficients >0.92 for all measures) of measurements of the dimensions of the central aponeurosis of the human tibialis anterior muscle from T1‐weighted scans. We conclude that valid and reliable measurements of aponeurosis dimensions can be obtained from UTE and from T1‐weighted scans. When the goal is to study the macroscopic architecture of aponeuroses, UTE does not hold an advantage over T1‐weighted imaging. [ABSTRACT FROM AUTHOR]

Key points: In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle–tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. Abstract: In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle–tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle–tendon lengths, (b) strong isometric contractions at short muscle–tendon lengths, (c) weak isometric contractions at long muscle–tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle–tendon slack angles and fascicle slack lengths. Contraction at short muscle–tendon lengths caused a mean 13.5 degree (95% CI 11.8–15.0 degree) shift in the muscle–tendon slack angle towards shorter muscle–tendon lengths, and a mean 5 mm (95% CI 2–8 mm) reduction in fascicle slack length, compared to the other conditions. A supplementary experiment showed the effect could be demonstrated if the muscle was conditioned by contraction at short lengths but not if the relaxed muscle was held at short lengths, confirming the role of muscle contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. [ABSTRACT FROM AUTHOR]

This study tested the hypothesis that the ratio of changes in muscle fascicle and tendon length that occurs with joint movement scales linearly with the ratio of the slack lengths of the muscle fascicles and tendons. We compared the contribution of muscle fascicles to passive muscle-tendon lengthening in muscles with relatively short and long fascicles. Fifteen healthy adults participated in the study. The medial gastrocnemius, tibialis anterior, and brachialis muscle-tendon units were passively lengthened by slowly rotating the ankle or elbow. Change in muscle fascicle length was measured with ultrasonography. Change in muscle-tendon length was calculated from estimated muscle moment arms. Change in tendon length was calculated by subtracting change in fascicle length from change in muscle-tendon length. The median (IQR) contribution of muscle fascicles to passive lengthening of the muscle-tendon unit, measured as the ratio of the change in fascicle length to the change in muscle-tendon unit length, was 0.39 (0.26-0.48) for the medial gastrocnemius, 0.51 (0.29-0.60) for tibialis anterior, and 0.65 (0.49-0.90) for brachialis. Brachialis muscle fascicles contributed to muscle-tendon unit lengthening significantly more than medial gastrocnemius muscle fascicles, but less than would be expected if the fascicle contribution scaled linearly with the ratio of muscle fascicle and tendon slack lengths. [ABSTRACT FROM AUTHOR]

Background: Risk factors for preeclampsia are well established, whereas, the triggers associated with timing of preeclampsia onset are not. The aim of this study was to establish whether recent infection or other triggers were associated with timing of preeclampsia onset.Methods: We used a case-crossover design with preeclampsia cases serving as their own controls. Women with singleton pregnancies of ≥20 weeks gestation presenting at three hospitals were eligible for inclusion. Exposures to potential triggers were identified via guided questionnaire. Infective episodes included symptoms lasting >24 h. Preeclampsia was defined as hypertension (BP ≥140 mmHg and/or ≥90 mmHg) and proteinuria (protein/creatinine ratio ≥30 mg/mmol). Conditional logistic regression was used to compare the odds of exposure to potential triggers in the case windows (1-7 days preceding diagnosis of preeclampsia) and control windows (8-14 days prior to diagnosis); unadjusted odds ratios (ORs) are reported.Results: Among 286 recruited women, 25 (8.7%) reported a new infection in the 7 days prior to preeclampsia onset and 21 (7.3%) in the 8-14 days prior. There was no significant association between onset of infection in the 7 days prior and preeclampsia diagnosis (OR 1.24, 95% CI 0.65, 2.34). Consumption of caffeine (OR 0.51, 95% CI 0.33, 0.77), spicy food (OR 0.49, 95% CI 0.30, 0.81), and alcohol (OR 0.26, 95% CI 0.10, 0.71) were strongly inversely associated with preeclampsia onset.Conclusion: Recent infection does not appear to trigger preeclampsia. Decreased consumption of caffeine, spicy food, and alcohol may be prodromal markers. Such behaviours may be early markers of imminent preeclampsia. [ABSTRACT FROM AUTHOR]

Precise estimates of muscle architecture are necessary to understand and model muscle mechanics. The primary aim of this study was to estimate continuous changes in fascicle length and pennation angle in human gastrocnemius muscles during ramped plantar flexor contractions at two ankle angles. The secondary aim was to determine whether these changes differ between proximal and distal fascicles. Fifteen healthy subjects performed ramped contractions (0-25% MVC) as ultrasound images were recorded from the medial ( MG, eight sites) and lateral ( LG, six sites) gastrocnemius muscle with the ankle at 90° and 120° (larger angles correspond to shorter muscle lengths). In all subjects, fascicles progressively shortened with increasing torque. MG fascicles shortened 5.8 mm (11.1%) at 90° and 4.5 mm (12.1%) at 120°, whereas LG muscle fascicles shortened 5.1 mm (8.8%) at both ankle angles. MG pennation angle increased 1.4° at 90° and 4.9° at 120°, and LG pennation angle decreased 0.3° at 90° and increased 2.6° at 120°. Muscle architecture changes were similar in proximal and distal fascicles at both ankle angles. This is the first study to describe continuous changes in fascicle length and pennation angle in the human gastrocnemius muscle during ramped isometric contractions. Very similar changes occurred in proximal and distal muscle regions. These findings are relevant to studies modeling active muscle mechanics. [ABSTRACT FROM AUTHOR]

Introduction: In this study we compared passive mechanical properties of gastrocnemius muscle-tendon units, muscle fascicles, and tendons in control subjects and people with ankle contractures after spinal cord injury. Methods: Passive gastrocnemius length-tension curves were derived from passive ankle torque-angle data obtained from 20 spinal cord injured subjects with ankle contractures and 30 control subjects. Ultrasound images of muscle fascicles were used to partition length-tension curves into fascicular and tendinous components. Results: Spinal cord injured subjects had stiffer gastrocnemius muscle-tendon units (stiffness index: 74.8 ± 27.0 m−1) than control subjects (54.4 ± 17.7 m−1) ( P = 0.004). Muscle-tendon slack lengths, as well as slack lengths and changes in length of fascicles and tendons, were similar in the two groups. Conclusions: People with ankle contractures after spinal cord injury have stiff gastrocnemius muscle-tendon units. It is not clear whether this reflects changes in properties of muscle fascicles or tendons. Muscle Nerve 46: 237-245, 2012 [ABSTRACT FROM AUTHOR]

Aim Conventional constraint-based therapies are intensive and demanding to implement, particularly for children. Modified forms of constraint-based therapies that are family-centred may be more acceptable and feasible for families of children with cerebral palsy (CP)-but require rigorous evaluation using randomized trials. The aim of this study was to determine the effects of modified constraint-induced therapy compared with intensive occupational therapy on activities of daily living and upper limb outcomes in children with hemiplegic CP. Method In this assessor-blinded pragmatic randomized trial, 50 children (27 males, 23 females; age range 19mo-7y 10mo) with hemiplegic CP were randomized using a concealed allocation procedure to one of two 8-week interventions: intensive occupational therapy ( n=25), or modified constraint-induced therapy ( n=25). Manual Ability Classification System (MACS) levels of the participants were, level I n=2, II n=37, III n=8, and level IV n=1; Gross Motor Function Classification System (GMFCS) levels were, level I n=33, level II n=15, and level III n=1. Participants were recruited through three specialist CP centres in Australia and randomized between January 2008 and April 2010. Children randomized to modified constraint-induced therapy wore a mitt on the unaffected hand for 2 hours each day, during which time the children participated in targeted therapy. The primary outcome was the Canadian Occupational Performance Measure (COPM - measured on a 10-point scale) at completion of therapy. Other outcome measures were Goal Attainment Scaling, Assisting Hand Assessment, Pediatric Motor Activity Log, Modified Ashworth Scale, Modified Tardieu Scale, and a parent questionnaire. Assessments were carried out at 10 weeks and 6 months following randomization. Results All participants were included in the analysis. Between-group differences for all outcomes were neither clinically important nor statistically significant. The mean difference in COPM was 0.3 (95% confidence interval [CI] −0.8 to 1.4; p=0.61) and mean difference in COPM satisfaction was 0.1 (95% CI −1.1 to 1.2; p=0.90). Minor adverse events were reported by five of the 25 participants in the modified constraint-induced therapy group and by one of the 25 in the intensive occupational therapy group. All adverse events were related to participants' lack of acceptance of therapy. Interpretation Modified constraint-induced therapy is no more effective than intensive occupational therapy for improving completion of activities of daily living or upper limb function in children with hemiplegic CP. [ABSTRACT FROM AUTHOR]

Non-Technical Summary Relaxed skeletal muscles behave like springs that resist joint motion. There have been few in vivo studies of the spring-like properties of relaxed muscles. In this study, ultrasound was used to image human calf muscles while muscle length was changed by rotating the ankle of relaxed subjects. The muscles of some subjects buckled at short lengths. At short lengths most muscle fascicles (bundles of muscle cells) are slack. As the muscle is lengthened the slack is progressively taken up, first in some fascicles then in others. The increase in muscle length is due partly to increases in the length of muscle fascicles but most of the increase in muscle length occurs in the tendons. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the prevalence of serious pathology in patients who receive primary care for their acute low back pain. It states that 1,172 patients were recruited from primary care clinics in Sydney, Australia and found out that only 11 cases have serious pathology. The study concludes that serious pathology is rare in patients with back pain presenting to a primary care provider and the common serious pathology is vertebral fracture.

OBJECTIVES: To determine the effects of exercise on falls prevention in older people and establish whether particular trial characteristics or components of exercise programs are associated with larger reductions in falls. DESIGN: Systematic review with meta-analysis. Randomized controlled trials that compared fall rates in older people who undertook exercise programs with fall rates in those who did not exercise were included. SETTING: Older people. PARTICIPANTS: General community and residential care. MEASUREMENTS: Fall rates. RESULTS: The pooled estimate of the effect of exercise was that it reduced the rate of falling by 17% (44 trials with 9,603 participants, rate ratio (RR)=0.83, 95% confidence interval (CI)=0.75–0.91, P<.001, I2=62%). The greatest relative effects of exercise on fall rates (RR=0.58, 95% CI=0.48–0.69, 68% of between-study variability explained) were seen in programs that included a combination of a higher total dose of exercise (>50 hours over the trial period) and challenging balance exercises (exercises conducted while standing in which people aimed to stand with their feet closer together or on one leg, minimize use of their hands to assist, and practice controlled movements of the center of mass) and did not include a walking program. CONCLUSION: Exercise can prevent falls in older people. Greater relative effects are seen in programs that include exercises that challenge balance, use a higher dose of exercise, and do not include a walking program. Service providers can use these findings to design and implement exercise programs for falls prevention. [ABSTRACT FROM AUTHOR]

A response by M. Wallen et al to a letter to the editor about their article "Modified Constraint-Induced Therapy for Children With Hemiplegic Cerebral Palsy: A Randomized Trial" in a 2011 issue is presented.

An abstract of the article "Passive mechanical properties of human gastrocnemius muscle-tendon units," by Robert D. Herbert and Joanna Diong is presented.