title: Feasibility and reliability of quantifying passive muscle stiffness in young children by using shear wave ultrasound elastography.
abstract: OBJECTIVE
  The purpose of this study was to investigate the feasibility and reliability of passive muscle stiffness measurements in children by shear wave ultrasound elastography.
  
  
  METHODS
  We conducted a prospective cross-sectional study quantifying the passive stiffness of bilateral lateral gastrocnemius muscles during passive stretching in 20 typically developing children (age range, 2.0-12.6 years). Data collected included passive stiffness of the lateral gastrocnemius muscle (shear modulus in kilopascals) at 4 positions of progressive passive foot dorsiflexion, demographic characteristics of the participants, and comparison of demographic characteristics with the shear modulus.
  
  
  RESULTS
  Passive stiffness increased with increasing stretching (mean [SD] range of stiffness, 7.1 [2.0] to 36.2 [22.0] kPa). For all 4 foot positions, no significant difference was found between right and left legs (range, P = .42 to P = .98) or between the sexes (range, P = .28 to P > .99). No correlation of passive muscle stiffness with age, body mass index, or ankle range of motion was found. The reliability of measurements was good to excellent (mean [95% confidence interval] range of reliability, 0.67 [0.44-0.83] to 0.80 [0.63-0.90]).
  
  
  CONCLUSIONS
  Measurements of passive stiffness of the lateral gastrocnemius muscle are feasible and reliable in children as young as 2 years. Because this study found no significant difference between sex and the side tested in this age group, future studies involving children of this age range may not need to be stratified on the basis of these parameters. Defining normal passive muscle stiffness in children is critical for identifying and understanding the implications of abnormal passive muscle stiffness in children with neuromuscular disorders.
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.). brandenburg.joline@mayo.edu.
authors: Joline E
authors: JE
authors: Brandenburg
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Sarah F
authors: SF
authors: Eby
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Pengfei
authors: P
authors: Song
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Heng
authors: H
authors: Zhao
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Bradford W
authors: BW
authors: Landry
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Shirley
authors: S
authors: Kingsley-Berg
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: William R
authors: WR
authors: Bamlet
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Shigao
authors: S
authors: Chen
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Gary C
authors: GC
authors: Sieck
authors: Departments of Physical Medicine and Rehabilitation (J.E.B.), Neurology (J.E.B., B.W.L.), Pediatric and Adolescent Medicine (J.E.B.), Physiology and Biomedical Engineering (P.S., H.Z., S.K.-B., S.C., G.C.S., K.-N.A.), and Health Sciences Research (W.R.B.) and Division of Orthopedic Research (K.-N.A.), Mayo Clinic, Rochester, Minnesota USA; and Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, Minnesota USA (S.F.E.).
authors: Kai-Nan
authors: KN
authors: An
mesh_terms: D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D054459:Elasticity Imaging Techniques; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000502:physiology*; D011446:Prospective Studies; D015203:Reproducibility of Results
keywords: elastography; feasibility; gastrocnemius muscle; pediatric ultrasound; pediatrics; skeletal muscle; ultrasound elastography