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Importance: The effects of altered neural processing, defined as altering neural networks responsible for perceptions of pain and function, on chronic pain remains unclear. Objective:To estimate the effect of a graded sensorimotor retraining intervention (RESOLVE) on pain intensity in people with chronic low back pain. Design, setting and participants: This parallel, 2-group, randomized clinical trial recruited participants with chronic (>3 months) nonspecific low back pain from primary care and community settings. A total of 276 adults were randomized (in a 1:1 ratio) to the intervention or sham procedure and attention control groups delivered by clinicians at a medical research institute in Sydney, Australia. The first participant was randomized on December 10, 2015, and the last was randomized on July 25, 2019. Follow-up was completed on February 3, 2020. Interventions: Participants randomized to the intervention group (n = 138) were asked to participate in 12 weekly clinical sessions and home training designed to educate them about and assist them with movement and physical activity while experiencing lower back pain. Participants randomized to the control group (n = 138) were asked to participate in 12 weekly clinical sessions and home training that required similar time as the intervention but did not focus on education, movement, and physical activity. The control group included sham laser and shortwave diathermy applied to the back and sham noninvasive brain stimulation. Main outcomes and measures: The primary outcome was pain intensity at 18 weeks, measured on an 11-point numerical rating scale (range, 0 [no pain] to 10 [worst pain imaginable]) for which the between-group minimum clinically important difference is 1.0 point. Results: Among 276 randomized patients (mean [SD] age, 46 [14.3] years; 138 [50%] women), 261 (95%) completed follow-up at 18 weeks. The mean pain intensity was 5.6 at baseline and 3.1 at 18 weeks in the intervention group and 5.8 at ba

Purpose: There have been contradictory reports of the effects of epimuscular myofascial force transmission in humans. This study investigated the transmission of myofascial force to the human vastus lateralis muscle by determining whether vastus lateralis slack angle changed with hip angle. Since the distance between the origin and insertion of the vastus lateralis muscle does not change when hip angle changes, any change in vastus lateralis slack angle with hip position can be attributed to epimuscular myofascial force transmission. Methods: Nineteen young adults were tested in hip flexed (80 ∘) and neutral (0 ∘) positions. Ultrasound images of the vastus lateralis muscle were obtained as the knee was passively flexed at 5 ∘/s. The knee angle at which vastus lateralis muscle fascicles began to lengthen was used to identify muscle slack angle. Results: Overall, there was a negligible effect of hip position on vastus lateralis slack angle (0. 6 ∘ [- 0.7 to 1.9]; mean [95% confidence interval]). However, a small and variable effect was noted in 3/19 participants. Conclusion: This result indicates that, over the range of joint angles tested here, there is little or no epimuscular myofascial force transmission between the vastus lateralis muscle and neighbouring bi-articular structures under passive conditions. More broadly, this result provides additional evidence that epimuscular myofascial force transmission tends to be small and variable under passive conditions in healthy human muscle.

Introduction The accurate quantification of the proportion of fat in human muscles could help monitor disease status and test effectiveness of interventions in people with neurological conditions whose skeletal muscles are frequently infiltrated with fat. Methods We compared two commonly used magnetic resonance imaging methods to quantify fat in muscles. Measurements were obtained before and after 6 or 8 wk of strength training in a total of 116 muscles spanning the range of intramuscular fat proportions observed in able-bodied young adults and people with spinal cord injury. Results We successfully measured fat proportions in all muscles using the mDixon method but were unable to obtain plausible measurements with the T1-weighted method from muscles of able-bodied individuals or from the leaner 23% of muscles of people with spinal cord injury (muscles with less than approximately 8% fat). In muscles with more fat, measurements obtained with the two methods agreed well (intraclass correlation coefficient, 0.88; mean absolute difference, 5%). We also found that, compared with the T1-weighted method, the mDixon method provides a more detailed characterization of fat infiltration in muscle and a less variable measurement of the effect of training on the proportion of fat. The mDixon method showed that 6 or 8 wk of strength training did not appreciably change the proportion of intramuscular fat in either people with spinal cord injury or able-bodied people. Conclusion On the basis of these findings, we recommend the use of mDixon methods in preference to T1-weighted methods to determine the effectiveness of interventions aimed at reducing intramuscular fat.

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.

Study design: Randomised controlled trial. Objectives: To determine the effectiveness of a sustainable community-based intervention designed to prevent serious complications and death 2 years after discharge in people with spinal cord injury in Bangladesh. Setting: Bangladesh. Methods: A pragmatic randomised controlled trial was undertaken. People who had sustained a spinal cord injury in the preceding 2 years, were wheelchair-dependent, and were about to be discharged from hospital in Bangladesh were recruited and randomised to an Intervention or Control group using a concealed allocation procedure stratified by level of lesion (tetraplegia/paraplegia). Participants in the Intervention group received 36 phone calls and three home visits over the first 2 years following discharge. All participants received usual post-discharge care. Survival status and date of death were determined by blinded assessors 2 years after randomisation. Results: Between July 2015 and March 2018, 410 participants were randomised (204 to Intervention, 206 to Control). There was no loss to follow up. At 2 years, 15 (7.4%) participants in the Intervention group and 16 (7.8%) participants in the Control group had died (hazard ratio from unadjusted Cox model = 0.93 [95% CI, 0.46 to 1.89]; p from log rank test 0.85). There were no clinically important or statistically significant average causal effects of intervention on the incidence or severity of complications. Conclusion: A program of community-based care for people with recent spinal cord injury in Bangladesh involving frequent phone contact and occasional in-person contact with a health professional after discharge from hospital is no better at preventing death at 2 years than usual care.

People who have had a stroke often develop ankle contractures which may be caused by changes in architecture of calf muscles. Anatomically constrained diffusion tensor imaging has recently been used to make three-dimensional, whole-muscle measurements of muscle architecture. Here, we compared the architecture of the medial gastrocnemius muscle in the paretic and non-paretic sides of people who have had a hemiparetic stroke and control participants using novel imaging techniques. Methods: MRI techniques (diffusion tensor imaging and mDixon imaging) were used to obtain muscle volume, fascicle length, pennation angle, physiological cross-sectional area and curvature in 14 stroke patients (mean age 60 SD 13 years) and 18 control participants (mean age 66 SD 12 years). Findings: On average, the ankle on the paretic side had 11° (95% confidence interval 8 to 13°) less dorsiflexion range than on the non-paretic side, and 6° (1 to 13°) less dorsiflexion range than ankles of control participants. The medial gastrocnemius muscles on the paretic side were, on average, 15% (35.2 cm3, 95% confidence interval 5.2 to 65.2 cm3) smaller in volume than the muscles on the non-paretic side, and 16% (36.9 cm3, 95% confidence interval 3.1 to 70.6 cm3) smaller than in control participants. No statistically significant differences between paretic, non-paretic and control muscles were detected for fascicle length, pennation angle, physiological cross-sectional area or curvature. Conclusions: People with hemiparetic stroke and reduced range of motion have, on average, a smaller medial gastrocnemius muscle on the paretic side than on the non-paretic side. Other muscle architectural parameters appear unchanged.

Background: Many children with cerebral palsy develop muscle contractures. The mechanisms of contracture are not well understood. We investigated the possibility that, because fat is stiffer than passive muscle, elevated intramuscular fat contributes to contracture. In this cross-sectional study, we compared the quantity and distribution of intramuscular fat in muscles from typically developing children and children with cerebral palsy who have contractures. Methods: mDixon magnetic resonance images were obtained from the legs of 20 ambulant children with unilateral spastic cerebral palsy who had ankle contractures (mean age 11 SD 3 years, 13 male, mean moderate level contracture) and 20 typically developing children (mean age 11 SD 4 years, 13 male). The images were analyzed to quantify the intramuscular fat fraction of the medial gastrocnemius muscles. The amount and distribution of intramuscular fat were compared between muscles of children with cerebral palsy and typically developing children. Findings: In typically developing children, the medial gastrocnemius muscles had a mean intramuscular fat fraction of 4.7% (SD 1.6%). In children with cerebral palsy, the mean intramuscular fat fractions in the more- and less-affected medial gastrocnemius muscle were 11.4% (8.1%) and 6.9% (3.4%) respectively. There were small but statistically significant regional differences in the distribution of intramuscular fat. There was no evidence of a relationship between intramuscular fat fraction and severity of contracture. Interpretation: Children with cerebral palsy have higher proportions of intramuscular fat than typically developing children. There is no clear relationship between intramuscular fat fraction and dorsiflexion range of motion in children with cerebral palsy.

Objective: To compare intramuscular fat fraction in people who have ankle contractures following stroke with the intramuscular fat fraction in control participants. Design: mDixon MRI images were used to quantify intramuscular fat fractions in the medial gastrocnemius muscles of people who had experienced a hemiparetic stroke (n = 14, mean age 60 ± 13 years) and control participants (n = 18, mean age 66 ± 12 years). Results: Intramuscular fat fractions were similar in the paretic and non-paretic sides of stroke patients (mean on paretic side 14.5%, non-paretic side 12.8%, difference 1.6%, 95% confidence interval −0.7 to 4.1%). The intramuscular fat fraction on the paretic side was higher than in the control group (mean intramuscular fat fraction in control muscles 7.6%; difference 7.8%, 95% confidence interval 4.6–10.9%). The difference between intramuscular fat fractions in non-paretic and control legs increased with age. Body mass index was similar in stroke patients and controls. There was no association between medial gastrocnemius intramuscular fat fraction and dorsiflexion range. Conclusion: Muscles of stroke patients had elevated intramuscular fat fractions compared to muscles from control participants which were not explained by differences in body mass index. There is no clear relationship between intramuscular fat in the medial gastrocnemius muscle and dorsiflexion range of motion.

Design: Mixed methods study Setting: Community, Bangladesh Objectives: To understand how a community-based intervention for people with spinal cord injury (SCI) in Bangladesh was delivered as part of a randomised controlled trial and to gauge the perceptions of participants and healthcare professionals to the intervention. Methods: A community-based intervention was administered to 204 participants as part of a large randomised controlled trial (called the CIVIC trial). Case-managers followed-up participants with regular telephone calls and home visits over the first 2 years after discharge. The following data were collected alongside the trial: (i) chart audit of telephone calls and home visits (ii) recordings of 20 telephone calls (iii) interviews with 14 Intervention participants and four healthcare professionals including three case-managers. Results: Participants received the target number of telephone calls and home visits. Pressure injuries were identified as a problem during at least one telephone call by 43% of participants. Participants and case-managers valued regular telephone calls and home visits, and believed that calls and visits prevented complications and alleviated social isolation. Participants trusted case-managers and were confident in the care and advice provided. Case-managers expressed concerns that people with SCI in Bangladesh face many problems impacting on well-being and motivation stemming from poverty, limited employment opportunities, societal attitudes and inaccessible environments. Conclusion: A community-based intervention involving regular telephone calls and home visits was administered as intended and was well received by the recipients of the care. Nonetheless, people with SCI in Bangladesh face economic and social problems which cannot be fully addressed by this type of intervention alone.

The slack length of a relaxed skeletal muscle can be reduced by isometric contraction at short lengths ("contract-short conditioning"). This study explored how the effect of contract-short conditioning on muscle slack length is modified by 1) the intensity of the contraction, 2) the delay between the contraction and measurement of slack length, and 3) the amplitude of a stretch delivered to the relaxed muscle after the contraction. Muscle fascicles in the human vastus lateralis muscle were observed with ultrasound imaging while the relaxed muscle was lengthened by flexing the knee. The knee angle at which muscle fascicle slack was taken up was used as a proxy for muscle slack length. Conditioning the muscle with voluntary isometric (fixed-end) contractions at short muscle lengths reduced vastus lateralis muscle slack length, measured 60 s later, by a mean of 10. This effect was independent of contraction intensity from 5% to 100% maximal voluntary contraction. The effect was largest when first observed 5 s after the contraction, decayed about one-third by 60 s, and then remained nearly constant until the last observation 5 min after the contraction. A slow stretch given to the relaxed muscle after contract-short conditioning increased slack length (i.e., reduced the effect of contract-short conditioning). Slack length increased nonlinearly with stretch amplitude. Very large stretches (>30, possibly as large as 90) were required to abolish the effect of contract-short conditioning. The phenomena described here share some characteristics with, and may involve similar mechanisms to, passive force enhancement and muscle thixotropy.NEW & NOTEWORTHY The slack length of a relaxed human skeletal muscle is not fixed; it can be modified by contraction and stretch. Contraction of the human vastus lateralis muscle at short lengths reduces the muscles slack length. Even very weak contractions are sufficient to induce this effect. The effect persists for at least 5 min, Funding agencies: Australian National Health and MedicalResearch Council (NHMRC; Program Grant APP1055084). RDH is supportedby an NHMRC research fellowship.