Three-dimensional architecture and moment arms of human rotator cuff muscles in vivo: Interindividual, intermuscular, and intramuscular variations.

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.

Human lower leg muscles grow asynchronously.

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.

Early and intensive motor training to enhance neurological recovery in people with spinal cord injury: trial protocol.

STUDY DESIGN: Protocol for a multi-centre randomised controlled trial (the SCI-MT trial). OBJECTIVES: To determine whether 10 weeks of intensive motor training enhances neurological recovery in people with recent spinal cord injury (SCI). SETTING: Fifteen spinal injury units in Australia, Scotland, England, Italy, Netherlands, Norway, and Belgium. METHODS: A pragmatic randomised controlled trial will be undertaken. Two hundred and twenty people with recent SCI (onset in the preceding 10 weeks, American Spinal Injuries Association Impairment Scale (AIS) A lesion with motor function more than three levels below the motor level on one or both sides, or an AIS C or D lesion) will be randomised to receive either usual care plus intensive motor training (12 h of motor training per week for 10 weeks) or usual care alone. The primary outcome is neurological recovery at 10 weeks, measured with the Total Motor Score from the International Standards for Neurological Classification of SCI. Secondary outcomes include global measures of motor function, ability to walk, quality of life, participants' perceptions about ability to perform self-selected goals, length of hospital stay and participants' impressions of therapeutic benefit at 10 weeks and 6 months. A cost-effectiveness study and process evaluation will be run alongside the trial. The first participant was randomised in June 2021 and the trial is due for completion in 2025. CONCLUSIONS: The findings of the SCI-MT Trial will guide recommendations about the type and dose of inpatient therapy that optimises neurological recovery in people with SCI. TRIAL REGISTRATION: ACTRN12621000091808 (1.2.2021).

Arthroscopic capsular shift surgery in patients with atraumatic shoulder joint instability: a randomised, placebo-controlled trial.

OBJECTIVES: To determine the effect of arthroscopic capsular shift surgery on pain and functional impairment for people with atraumatic shoulder (glenohumeral) joint instability. METHODS: We conducted a randomised, placebo-controlled clinical trial in a specialist secondary care facility. Patients aged 18 years and over who reported insecurity (apprehension) in their shoulder joint and had evidence of capsulolabral damage on arthroscopic examination were included. Patients were excluded if their shoulder apprehension symptoms were precipitated by a high velocity shoulder injury, they had bony or neural damage, a rotator cuff or labral tear, or previous surgery on the symptomatic shoulder. Sixty-eight participants were randomised and received diagnostic arthroscopy, followed by arthroscopic capsular shift or diagnostic arthroscopy alone. All participants received the same postoperative clinical care. The primary outcome was pain and functional impairment measured with the Western Ontario Shoulder Instability Index. The prespecified minimum clinically important effect was a reduction in pain and disability of 10.4 points. RESULTS: Mean reductions in pain and functional impairment for both groups were similar. Compared with diagnostic arthroscopy, arthroscopic capsular shift increased pain and functional impairment by means of 5 points (95% CI -6 to 16 points) at 6 months, 1 point (95% CI -11 to 13 points) at 12 months and 2 points (95% CI -12 to 17 points) at 24 months. CONCLUSIONS: Compared with diagnostic arthroscopy alone, arthroscopic capsular shift confers, at best, only minimal clinically important benefit in the medium term. TRIAL REGISTRATION NUMBER: NCT01751490.

Post-fracture serum cytokine levels are not associated with a later diagnosis of complex regional pain syndrome: a case-control study nested in a prospective cohort study.

BACKGROUND: Complex Regional Pain Syndrome (CRPS) is a disabling pain disorder that is most common after a distal limb fracture. While the acute systemic immune response to the injury is thought to play a role in the development of CRPS, this hypothesis has never been tested directly. Thus, we evaluated whether elevated levels of circulating pro-inflammatory cytokines early after a fracture were associated with the development of CRPS. METHODS: We conducted a case-control study nested within a prospective cohort study. Individuals with wrist and/or hand fractures were recruited from specialist hand units. Baseline clinical data were obtained from participants within 28 days of fracture. CRPS status was determined 16 weeks after the fracture using a two-stage diagnostic process. Cytokine assays were obtained from all cases (defined using the Budapest criteria) and a random sample of those who did not have CRPS at 16 weeks. We calculated odds ratios with 95% confidence intervals to determine the risk of CRPS associated with the expression of each of 25 cytokines. RESULTS: Baseline data were collected for 702 consenting participants, of whom 535 provided blood samples. Follow-up at 16 weeks was 97.2%. 15 (2.2% of the cohort) met the Budapest CRPS criteria and 69 (including those who met the Budapest criteria; 9.8%) met the International Association for the Study of Pain (IASP) CRPS criteria. In all of the primary analyses (using Budapest criteria) and 49/50 secondary analyses (using IASP criteria), 95% confidence intervals for the association between cytokine levels and the risk of subsequently developing CRPS included the null value (OR = 1). However, the confidence intervals were wide. CONCLUSION: There was no evidence that early post-injury expression of systemic cytokines was associated with a CRPS diagnosis 16 weeks after injury. This study does not provide support for the hypothesis that innate immune activation has a determinative role in the development of CRPS.

Incidence, severity and time course of pressure injuries over the first two years following discharge from hospital in people with spinal cord injuries in Bangladesh.

DESIGN: Cohort study embedded in a clinical trial. SETTING: Community, Bangladesh. OBJECTIVES: To determine the incidence, severity and time course of pressure injuries over the first two years following discharge from hospital in people with spinal cord injuries (SCI) in Bangladesh. METHODS: Participants (n = 186) were contacted by telephone 39 times and assessed face-to-face 4 to 6 times over the two years following discharge. At each point of contact the presence and severity of pressure injuries were determined using the Pressure Ulcer Scale for Healing (PUSH). Survival analyses were conducted to determine the time course of development of pressure injuries and recovery from pressure injuries. Lasso regression was used to construct multivariable prediction models. RESULTS: Seventy-seven participants (41%; 95% CI 34% to 49%) developed at least one pressure injury in the first two years after discharge (incidence rate 0.27 per person-year, 95% CI 0.22 to 0.34). Most pressure injuries were on the sacrum (23%). Pressure injuries took a median (IQR) of 40 (29 to 57) days to heal. The median (IQR) peak PUSH score was 11.0/17 (8.0 to 13.5). The multivariable prediction models had poor predictive properties (maximum c-statistic 0.75). CONCLUSION: Pressure injuries impose a large health burden on people with SCI in Bangladesh. However, they are difficult to predict, treat and prevent. Further research is needed to identify who is at most risk and to find solutions for the treatment and prevention of pressure injuries in Bangladesh and other low-middle income countries.

Effect of Graded Sensorimotor Retraining on Pain Intensity in Patients With Chronic Low Back Pain: A Randomized Clinical Trial.

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 baseline and 4.0 at 18 weeks in the control group, with an estimated between-group mean difference at 18 weeks of -1.0 point ([95% CI, -1.5 to -0.4]; P = .001), favoring the intervention group. Conclusions and Relevance: In this randomized clinical trial conducted at a single center among patients with chronic low back pain, graded sensorimotor retraining, compared with a sham procedure and attention control, significantly improved pain intensity at 18 weeks. The improvements in pain intensity were small, and further research is needed to understand the generalizability of the findings. Trial Registration: ANZCTR Identifier: ACTRN12615000610538.

Deep learning methods for automatic segmentation of lower leg muscles and bones from MRI scans of children with and without cerebral palsy.

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.

Negligible epimuscular myofascial force transmission between the human rectus femoris and vastus lateralis muscles in passive conditions.

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 ([Formula: see text]) and neutral ([Formula: see text]) positions. Ultrasound images of the vastus lateralis muscle were obtained as the knee was passively flexed at [Formula: see text]/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 ([Formula: see text] [[Formula: see text] 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.

A community-based intervention to prevent serious complications and death 2 years after discharge in people with spinal cord injury in Bangladesh (CIVIC): a randomised trial.

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.

Clinical Course of Pain and Function Following Total Knee Arthroplasty: A Systematic Review and Meta-Regression.

BACKGROUND: Total knee arthroplasty (TKA) is widely considered a successful intervention for osteoarthritis and other degenerative knee diseases. This study addresses the need for a high-quality meta-analysis that outlines the clinical course of pain and function post-TKA. METHODS: The review included prospective cohort studies assessing pain or function of patients undergoing primary TKA at baseline (preoperatively) and at least 2 additional time points including one at least 12 months postoperatively. Two reviewers independently screened references, extracted data, and assessed risk of bias using the Quality in Prognosis Studies tool. The time course of recovery of pain and function was modeled using fractional polynomial meta-regression. RESULTS: In total, 191 studies with 59,667 patients were included, most with low risk of bias. The variance-weighted mean pain score (/100, 0 = no pain) was 64.0 (95% confidence interval [CI] 60.2-67.7) preoperatively, 24.1 (95% CI 20.3-27.9) at 3 months, 20.4 (95% CI 16.7-24.0) at 6 months, and 16.9 (95%CI 13.6-20.3) at 12 months, and remained low (10.1; 95% CI 4.8-15.4) at 10 years postoperatively. The variance-weighted mean function score (/100, 0 = worst function) was 47.1 (95% CI 45.7-48.4) preoperatively, 72.8 (95% CI 71.3-74.4) at 3 months, 76.3 (95% CI 74.7-77.8) at 6 months, and 78.1 (95%CI 76.4-79.7) at 12 months. Function scores were good (79.7; 95% CI 77.9-81.5) at 10 years postoperatively. CONCLUSION: Patients undergoing primary TKA can expect a large and rapid but incomplete recovery of pain and function in the first postoperative year. At 10 years, the gains in pain scores may still remain while there is an improvement in function.

Clinical course of patients with low back pain following an emergency department presentation: a systematic review and meta-analysis.

INTRODUCTION: Low back pain, and especially non-specific low back pain, is a common cause of presentation to the emergency department (ED). Although these patients typically report relatively high pain intensity, the clinical course of their pain and disability remains unclear. Our objective was to review the literature and describe the clinical course of non-specific low back pain after an ED visit. METHODS: Electronic searches were conducted using MEDLINE, CINAHL and EMBASE from inception to March 2019. We screened for cohort studies or randomised trials investigating pain or disability in patients with non-specific low back pain presenting to EDs. We excluded studies that enrolled participants with minimal pain or disability scores at baseline. Two reviewers independently screened the full texts, extracted the data and assessed risk of bias and quality of evidence. Estimates of pain and disability were converted to a common 0-100 scale. We estimated pooled means and 95% CIs of pain and disability as a function of time since ED presentation. RESULTS: Eight studies (nine publications) with a total of 1994 patients provided moderate overall quality evidence of the expected clinical course of low back pain after an ED visit. Seven of the eight studies were assessed to have a low risk of bias. At the time of the ED presentation, the pooled estimate of the mean pain score on a 0-100 scale was 71.0 (95% CI 64.2-77.9). This reduced to 46.1 (95% CI 37.2-55.0) after 1 day, 41.8 (95% CI 34.7 to 49.0) after 1 week and 13.5 (95% CI 5.8-21.3) after 26 weeks. The course of disability followed a similar pattern. CONCLUSIONS: Patients presenting to EDs with non-specific low back pain experience rapid reductions in pain intensity, but on average symptoms persisted 6 months later. This review can be used to educate patients so they can have realistic expectations of their recovery.

Loss of work-related income impoverishes people with SCI and their families in Bangladesh.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To determine the degree of impoverishment of people with spinal cord injury (SCI) and their families in Bangladesh caused by loss of work-related income following injury. SETTING: Spinal cord injury centre, Bangladesh. METHODS: A total of 410 wheelchair-dependent people with recent SCI about to be discharged from a hospital in Bangladesh were interviewed to determine the size of their families, their incomes from paid work prior to injury and the incomes of their family members. These data were used to calculate income per family unit and per family member prior to and immediately after injury. RESULTS: Ninety percent of the participants were men, 98% were from rural areas of Bangladesh and 58% were manual labours prior to injury. Median (interquartile range, IQR) family size was 5 (4-6) people. Prior to injury, 74% of participants were the main income earners for their families and 50% provided the only source of income for their families. Participants' median (IQR) monthly income prior to injury was US$106 (US$60-US$180) per person and family members' income was US$30 (US$19-US$48) per person. After injury, the median income (IQR) of each family member dropped to US$0 (US$0-US$18) placing 91% of families below the extreme poverty line of US$37.50 per person per month (equivalent to US$1.25 per day). CONCLUSION: In Bangladesh, SCI have profound financial implications for individuals and their families and causes extreme poverty. This is because those most often injured are young and the main income earners for their families.

Understanding how a community-based intervention for people with spinal cord injury in Bangladesh was delivered as part of a randomised controlled trial: a process evaluation.

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.

Validity and reliability of measurements of aponeurosis dimensions from magnetic resonance images.

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.

A preliminary investigation of mechanisms by which short-term resistance training increases strength of partially paralysed muscles in people with spinal cord injury.

STUDY DESIGN: Pretest-posttest design. OBJECTIVES: To investigate mechanisms by which short-term resistance training (6 weeks) increases strength of partially paralysed muscles in people with spinal cord injury (SCI). SETTING: Community-based setting, Sydney, Australia. PARTICIPANTS: Ten community-dwelling people with partial paralysis of elbow flexor, elbow extensor, knee flexor or knee extensor muscles following SCI (range 5 months to 14 years since injury). METHODS: Muscle architecture and strength were assessed before and after participants underwent a six week strength-training program targeting one partially paralysed muscle group. The outcome of primary interest was physiological cross sectional area (PCSA) of the trained muscle group measured using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Other outcomes were changes in mean muscle fascicle length, muscle volume, pennation angle, isometric strength and muscle strength graded on a 13-point scale. RESULTS: The mean increase in maximal isometric muscle strength was 14% (95% CI, -3 to 30%) and 1.5 points (95% CI, 0.5 to 2.5) on the 13-point manual muscle test. There was no evidence of a change in muscle architecture. CONCLUSION: This study is the first to examine the mechanisms by which voluntary strength training increases strength of partially paralysed muscles in people with SCI. The data suggest that strength gains produced by six weeks of strength training are not caused by changes in muscle architecture. This suggests short-term strength gains are due to increased neural drive or an increase in specific muscle tension.

Health status, quality of life and socioeconomic situation of people with spinal cord injuries six years after discharge from a hospital in Bangladesh.

STUDY DESIGN: Cross-sectional analysis of a mixed retrospective and prospective inception cohort study. OBJECTIVES: To determine health status, quality of life and socioeconomic situation of people with spinal cord injuries (SCI) 6 years after discharge from a hospital in Bangladesh. SETTING: Bangladesh. METHODS: All patients alive 6 years after discharge from a hospital in Bangladesh were interviewed using the SF12 health survey, the SCI Secondary Conditions Scale, the Centre for Epidemiologic Studies Depression Scale (CESD), and the participation in society items of World Health Organisation Disability Assessment Schedule (WHODAS 2.0). Additional questions determined participants' socioeconomic and employment status. RESULTS: The cohort comprised 260 participants: 145 used wheelchairs for mobility and 115 were able to walk at discharge. The median (IQR) Mental and Physical Component scores for the SF12 were 54 (49-57) and 44 (40-51) points, respectively. The median scores for the SCI Secondary Conditions Scale, CESD and WHODAS 2.0 were 8 (4-13), 7 (4-13) and 12 (6-17) points, respectively. Fourteen percent of all participants and 23% of those who used wheelchairs had a pressure ulcer at the time of interview. Forty-four percent of participants were unemployed and 65% were living below the poverty line (median (IQR) income, USD 0 (0-91)) per month. CONCLUSION: Many people with SCI in Bangladesh are unemployed and living in poverty with a reduced quality of life and participation. Pressure ulcers are a common complication.

A prediction model to identify people with spinal cord injury who are at high risk of dying within 5 years of discharge from hospital in Bangladesh.

STUDY DESIGN: Mixed retrospective and prospective cohort study. OBJECTIVES: To determine 5-year survival after hospitalisation with spinal cord injury (SCI) in Bangladesh and to develop a prediction model to identify people at high risk of dying within 5 years. SETTING: Bangladesh. METHODS: Medical records were used to identify people with SCI admitted to a hospital in Bangladesh in 2011. Participants or their family members were contacted >5 years after discharge to determine vital status or date of death. Survival from time of discharge was estimated with Kaplan-Meier curves. A linear model of the log odds of death within 5 years of discharge was constructed and internally validated. RESULTS: Of the 345 people who were admitted and survived to discharge in 2011, 342 (99%) were accounted for 5 years later: 74 (22%) had died (survival = 78%; 95% CI 74-82%). Sixty nine of the 223 participants who were wheelchair-dependent at discharge had died (survival = 69%; 95% CI 62-75%). A parsimonious model predicted survival as a function of age and mode of mobility at discharge (wheelchair-dependent or ambulant). The odds of dying increased by a factor of 1.6 (95% CI, 1.3-2.0) with every decade of age and by a factor of 12.6 (95% CI, 4.8-32.9) if wheelchair-dependent. The model had good calibration and discrimination. CONCLUSION: The risk of dying after discharge from hospital with SCI in Bangladesh is high, especially among older, wheelchair-dependent people. A simple prediction model discriminates those at high risk of dying within 5 years.

History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

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.

Analysis of randomised trials with long-term follow-up.

Randomised trials with long-term follow-up can provide estimates of the long-term effects of health interventions. However, analysis of long-term outcomes in randomised trials may be complicated by problems with the administration of treatment such as non-adherence, treatment switching and co-intervention, and problems obtaining outcome measurements arising from loss to follow-up and death of participants. Methods for dealing with these issues that involve conditioning on post-randomisation variables are unsatisfactory because they may involve the comparison of non-exchangeable groups and generate estimates that do not have a valid causal interpretation. We describe approaches to analysis that potentially provide estimates of causal effects when such issues arise. Brief descriptions are provided of the use of instrumental variable and propensity score methods in trials with imperfect adherence, marginal structural models and g-estimation in trials with treatment switching, mixed longitudinal models and multiple imputation in trials with loss to follow-up, and a sensitivity analysis that can be used when trial follow-up is truncated by death or other events. Clinical trialists might consider these methods both at the design and analysis stages of randomised trials with long-term follow-up.