Effect of Knee Flexion Angle on Achilles Tendon Force and Ankle Joint Plantarflexion Moment During Passive Dorsiflexion

Early mobilization exercises are advocated following Achilles tendon (AT) repair, but forces on the repair during passive range of motion are unknown. The extent to which these forces change with flexion of the knee is also not known. Estimated AT forces were measured using 3 models: cadaveric, uninjured subjects, and in both legs of subjects 6 weeks following unilateral AT repair. For cadaveric testing, estimated AT force was recorded using a force transducer while cycling the ankle from 10 degrees plantarflexion to maximum dorsiflexion at 3 different knee flexion angles (0 degrees , 45 degrees , and 90 degrees ). For in vivo testing, subjects were seated in an isokinetic dynamometer, and their ankles passively cycled from plantarflexion to dorsiflexion with the knee extended and flexed 50 degrees . Passive plantarflexion moment recorded by the dynamometer was converted to AT force by estimating the AT moment arm. In the cadaveric model, knee flexion reduced estimated AT forces during dorsiflexion by more than 40% (P < .036). In vivo testing showed that estimated AT force was reduced in knee flexion in healthy subjects (P < .001) and in the uninvolved leg AT repair subjects (P = .021), but not in the AT repaired leg (P = .387). Normal AT showed a marked reduction in estimated AT force with knee flexion which was not present in repaired AT. This could be because of elongation of the repair, causing more slack in the tendon that would need to be taken up before force transmission occurs. ACFAS Level of Clinical Evidence: 4.     

International multidisciplinary collaboration toward an annotated definition of arthrogryposis multiplex congenita

Arthrogryposis multiplex congenita (AMC) has been described and defined in thousands of articles, but the terminology used has been inconsistent in clinical and research communities. A definition of AMC was recently developed using a modified Delphi consensus method involving 25 experts in the field of AMC from 8 countries. Participants included health care professionals, researchers, and individuals with AMC. An annotation of the definition provides more in‐depth explanations of the different sentences of the AMC definition and is useful to complement the proposed definition. The aim of this study was to provide an annotation of the proposed consensus‐based AMC definition. For the annotation process, 17 experts in AMC representing 10 disciplines across 7 countries participated. A paragraph was developed for each sentence of the definition using an iterative process involving multiple authors with varied and complementary expertise, ensuring all points of view were taken into consideration. The annotated definition provides an overview of the different topics related to AMC and is intended for all stakeholders, including youth and adults with AMC, their families, and clinicians and researchers, with the hopes of unifying the understanding of AMC in the international community.     

Conference report on contractures in musculoskeletal and neurological conditions

Limb contractures are debilitating complications associated with various muscle and nervous system disorders. This report summarizes presentations at a conference at the Shirley Ryan AbilityLab in Chicago, Illinois, on April 19–20, 2018, involving researchers and physicians from diverse disciplines who convened to discuss current clinical and preclinical understanding of contractures in Duchenne muscular dystrophy, stroke, cerebral palsy, and other conditions. Presenters described changes in muscle architecture, activation, extracellular matrix, satellite cells, and muscle fiber sarcomeric structure that accompany or predispose muscles to contracture. Participants identified ongoing and future research directions that may lead to understanding of the intersecting factors that trigger contractures. These include additional studies of changes in muscle, tendon, joint, and neuronal tissues during contracture development with imaging, molecular, and physiologic approaches. Participants identified the requirement for improved biomarkers and outcome measures to identify patients likely to develop contractures and to accurately measure efficacy of treatments currently available and under development.     

Activity-based Therapies in Spinal Cord Injury:: Clinical Focus and Empirical Evidence in Three Independent Programs

This article summarizes presentations of a symposium examining the potential impact of activity-based therapies (ABT) in promoting neurological and functional recovery after spinal cord injury (SCI). The symposium addressed 3 key questions concerning activity-based therapy in SCI: (1) What clinical approaches are used? (2) Is there empirical evidence supporting efficacy of ABT in promoting neurological recovery and improving overall function, health, and quality of life? (3) What are the issues related to long-term viability of ABT?     

Falls and spinal muscular atrophy: Exploring cause and prevention

Introduction: Falls can cause injury and may compromise function in spinal muscular atrophy (SMA) patients. Weakness and gait variability are associated with falls in other neurological disorders, and fatigue is well documented in SMA. The relationship of weakness, fatigue, and gait variability to falls has never been investigated. Methods: Seven ambulatory patients with SMA completed a falls history questionnaire, 6MWT, gait analysis, and strength testing. Pearson correlation coefficients were used to examine associations between these variables. Results: All 7 subjects reported falls in the previous year. Stride‐length variability was significantly associated with falls, unlike strength, fatigue, or other gait variables. Conclusions: Stride‐length variability was the key variable associated with falls. Preventive strategies to avoid falls should be incorporated into patient management plans. Gait analysis provides actionable information not revealed by standard assessments and should be included in clinical trials designed to address the prevention of falls in the SMA population. Muscle Nerve, 2013     

Developing normalized strength scores for neuromuscular research

Introduction: The Accurate Test of Limb Isometric Strength (ATLIS) device can reliably measure the strength of 12 muscle groups using a fixed load cell. The purpose of this study was to analyze ATLIS data from healthy adults to calculate an individual's predicted strength scores. Methods: ATLIS data were collected from 432 healthy adults. Linear regression models were developed to predict each muscle group's strength. The R‐squared statistic assessed variability accounted for by the models. Results: Simple main effects models stratified by gender were used to establish regression equations for each muscle using factors of age, weight, and height. Conclusions: Normalizing raw strength scores controls for biometric factors, thus enabling meaningful comparisons between subjects and allowing each muscle to contribute equally to a summary score. Normalized scores are easily interpreted for broad clinical uses, and derived summary scores establish individuals' disease progression rates using a common scale, allowing for more efficient clinical trials. Muscle Nerve, 2013