title: Medial gastrocnemius and soleus muscle-tendon unit, fascicle, and tendon interaction during walking in children with cerebral palsy.
abstract: This study investigates the in vivo function of the medial gastrocnemius and soleus muscle-tendon units (MTU), fascicles, and tendons during walking in children with cerebral palsy (CP) and an equinus gait pattern.
  
  
  
  Fourteen children with CP (9 males, 5 females; mean age 10y 6mo, standard deviation [SD] 2y 11mo; GMFCS level I=8, II=6), and 10 typically developing (6 males, 4 females; mean age 10y, SD 2y 1mo) undertook full body 3D gait analysis and simultaneous B-mode ultrasound images of the medial gastrocnemius and soleus fascicles during level walking. Fascicle lengths were analysed using a semi-automated tracking algorithm and MTUs using OpenSim. Statistical parametric mapping (two-sample t-test) was used to compare differences between groups (p<0.05).
  
  
  
  In the CP group medial gastrocnemius fascicles lengthened during mid-stance gait and remained longer into late-stance compared to the typically developing group (p<0.001). CP medial gastrocnemius fascicles shortened less during stance (1.16mm [SD 1.47mm]) compared to the typically developing group (4.48mm [SD 1.94mm], p<0.001). In the CP group the medial gastrocnemius and soleus MTU and tendon were longer during early- and mid-stance (p<0.001). Ankle power during push-off (p=0.015) and positive work (p<0.002) and net work (p<0.001) were significantly lower in the CP group.
  
  
  
  Eccentric action of the CP medial gastrocnemius muscle fascicles during mid-stance walking is consistent with reduced volume and neuromuscular control of impaired muscle. Reduced ankle push-off power and positive work in the children with CP may be attributed to reduced active medial gastrocnemius fascicle shortening. These findings suggest a reliance on passive force generation for forward propulsion during equinus gait.
authors.affiliation: Queensland Cerebral Palsy and Rehabilitation Research Centre, Child Health Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, Australia.
authors.forename: Lee
authors.identifier: 0000-0002-3220-3078
authors.initials: L
authors.lastname: Barber
authors.affiliation: Queensland Children's Motion Analysis Service, Children's Health Queensland Hospital and Health Service, Brisbane, Australia.|Centre for Musculoskeletal Research, Menzies Health Institute Queensland, Gold Coast, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Carty
authors.affiliation: Centre for Musculoskeletal Research, Menzies Health Institute Queensland, Gold Coast, Australia.|Department of Mechanical Engineering and INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, UK.
authors.forename: Luca
authors.initials: L
authors.lastname: Modenese
authors.affiliation: Queensland Children's Motion Analysis Service, Children's Health Queensland Hospital and Health Service, Brisbane, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Walsh
authors.affiliation: Queensland Cerebral Palsy and Rehabilitation Research Centre, Child Health Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, Australia.
authors.forename: Roslyn
authors.initials: R
authors.lastname: Boyd
authors.affiliation: School of Human Movement Studies, The University of Queensland, St Lucia, Australia.
authors.forename: Glen
authors.initials: G
authors.lastname: Lichtwark
mesh_terms: D000842:Ankle / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002648:Child; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013710:Tendons / Q000503:physiopathology*; D014463:Ultrasonography; D016138:Walking / Q000502:physiology*