Background: Cerebral palsy (CP) is an upper motor neuron disease that results in a progressive movement disorder. Secondary to the neurological insult, muscles from CP patients often become spastic. Spastic muscle is characterized by an increased resistance to stretch, but often develops the further complication of contracture which represents a prominent disability in children with CP. This study's purpose is to characterize alterations of spastic muscle on the transcriptional level. Increased knowledge of spastic muscle may lead to novel therapies to improve the quality of life for children with CP.

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The present study provides novel data suggesting a role for pro-inflammatory cytokines and reduced ribosomal production in the development/maintenance of muscle contractures, possibly underlying stunted growth and perimysial ECM expansion. Muscle Nerve 58: 277-285, 2018.

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.

Children with cerebral palsy often have spasticity of both the extensors and flexors, but how and why a flexion contracture of the wrist will develop during growth is not thoroughly understood. In order to understand the muscle adaptations that occur during contracture formation, the relationship between intraoperative sarcomere length and the extent of contracture was measured in 23 children (average age, 14.3 +/- 2.9 years) undergoing tendon transfers involving the flexor carpi ulnaris (FCU) or extensor carpi radialis brevis (ECRB) muscles. For both ECRB and FCU, sarcomere lengths measured intraoperatively were longer compared to sarcomere lengths predicted from a regression relationship obtained from "control" patients with radial nerve injury (P < 0.001). The most interesting aspect of the long FCU sarcomere lengths measured was that there was a highly significant correlation between the degree of contracture formation and intraoperative sarcomere length (r2 = 0.5, P < 0.005). These data clearly show that greater contracture severity is associated with longer intraoperative FCU sarcomere length. No such correlation was observed for the ECRB. The data suggest that the clinical presentation of the contracture is related to degree of FCU, but not ECRB adaptation, to the central nervous system lesion.

The objective of the study was to investigate the feasibility of modified constraint-induced (CI) therapy provided in a 2-week day-camp model with and without intramuscular botulinum toxin type A (BoNT-A) injections for children with congenital cerebral palsy. Sixteen children with congenital hemiplegia, Manual Ability Classification System (MACS) level I and II, aged 8-17 years, participated in a CI therapy day camp; of whom five participants (aged 11-16 years) received intramuscular BoNT-A prior to CI therapy. Assessments were conducted 4 months and 2 weeks before (baselines 1 and 2), immediately after, and 6 months after the day camp. For the children who received BoNT-A, no statistical analyses were conducted due to the small size of the sample. In this group, consistent improvement was only found according to the Melbourne Unilateral Limb Assessment. The children who received only the CI therapy demonstrated improvements in the Jebsen-Taylor Hand Function Test (p =. 04) at posttest, but improvements were not sustained at 6-month follow-up. No significant improvement was obtained for the Melbourne Assessment or the Assisting Hand Assessment. Children in both groups improved on specially trained tasks: frisbee golf, stacking blocks, and in-hand manipulation. Feedback from the participants suggests that the day-camp model is a feasible intervention following intramuscular BoNT-A injections. The results suggest that children with congenital hemiplegia with varying severity of impairment in hand function may benefit from CI therapy, but not every child demonstrates improvements in hand function. The characteristics of children who respond the best to CI therapy are not clear.

Muscle and joint contact force influence stresses at the proximal growth plate of the femur and thus bone growth, affecting the neck shaft angle (NSA) and femoral anteversion (FA). This study aims to illustrate how different muscle groups’ activation during gait affects NSA and FA development in able-bodied children. Subject-specific femur models were developed for three able-bodied children (ages 6, 7, and 11 years) using magnetic resonance images. Contributions of different muscle groups—hip flexors, hip extensors, hip adductors, hip abductors, and knee extensors—to overall hip contact force were computed. Specific growth rate for the growth plate was computed, and the growth was simulated in the principal stress direction at each element in the growth front. The predicted growth indicated decreased NSA and FA (of about over a four-month period) for able-bodied children. Hip abductors contributed the most, and hip adductors, the least, to growth rate. All muscles groups contributed to a decrease in predicted NSA (0.01–0.04 and FA (0.004–), except hip extensors and hip adductors, which showed a tendency to increase the FA (0.004–). Understanding influences of different muscle groups on long bone growth tendency can help in treatment planning for growing children with affected gait.Electronic supplementary materialThe online version of this article (doi:10.1007/s10237-017-0925-3) contains supplementary material, which is available to authorized users.

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