title: Altered knee joint neuromuscular control during landing from a jump in 10-15 year old children with Generalised Joint Hypermobility. A substudy of the CHAMPS-study Denmark.
abstract: Generalised Joint Hypermobility (GJH) is considered an intrinsic risk factor for knee injuries. Knee neuromuscular control during landing may be altered in GJH due to reduced passive stability. The aim was to identify differences in knee neuromuscular control during landing of the Single-Leg-Hop-for-Distance test (SLHD) in 25 children with GJH compared to 29 children without GJH (controls), all 10-15years. Inclusion criteria for GJH: Beighton score⩾5/9 and minimum one hypermobile knee. EMG was recorded from the quadriceps, the hamstring and the calf muscles, presented relative to Maximum Voluntary Electrical activity (MVE). There was no difference in jump length between groups. Before landing, GJH had 33% lower Semitendinosus, but 32% higher Gastrocnemius Medialis activity and 39% higher co contraction of the lateral knee muscles, than controls. After landing, GJH had 36% lower Semitendinosus activity than controls, all significant findings. Although the groups performed equally in SLHD, GJH had a Gastrocnemius Medialis dominated neuromuscular strategy before landing, plausibly caused by reduced Semitendinosus activity. Reduced Semitendinosus activity was seen in GJH after landing, but with no compensatory Gastrocnemius Medialis activity. Reduced pre and post-activation of the Semitendinosus may present a risk factor for traumatic knee injuries as ACL ruptures in GJH with knee hypermobility.
authors: Institute of Regional Health Services, University of Southern Denmark, Odense, Denmark; Department of Physiotherapy, University College Lillebaelt, Odense, Denmark; Health Sciences Research Centre, University College Lillebaelt, Odense, Denmark. Electronic address: tjunge@health.sdu.dk.
authors: Tina
authors: T
authors: Junge
authors: Institute of Regional Health Services, University of Southern Denmark, Odense, Denmark; Spine Centre of Southern Denmark, Hospital Lillebaelt, Middelfart, Denmark.
authors: Niels
authors: N
authors: Wedderkopp
authors: Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors: Jonas Bloch
authors: JB
authors: Thorlund
authors: Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors: Karen
authors: K
authors: Søgaard
authors: Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Institute of Occupational Therapy, Physiotherapy and Radiography, Bergen University College, Bergen, Norway.
authors: Birgit
authors: B
authors: Juul-Kristensen
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology*; D007719:Knee Joint / Q000502:physiology / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000502:physiology / Q000503:physiopathology
keywords: Children; Generalised Joint Hypermobility; Knee injuries; Neuromuscular control; Single-leg-Hop-for-Distance test