Annika Kruse1, Christian Schranz2, Martin Svehlik3, Markus Tilp4. 1. Institute of Sports Science, University of Graz, Mozartgasse 14, 8010 Graz, Austria. Electronic address: annika.kruse@edu.uni-graz.at. 2. Paediatric Orthopaedics, Department of Paediatric Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz, Austria. Electronic address: christian.schranz@stud.medunigraz.at. 3. Paediatric Orthopaedics, Department of Paediatric Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz, Austria. Electronic address: martin.svehlik@medunigraz.at. 4. Institute of Sports Science, University of Graz, Mozartgasse 14, 8010 Graz, Austria. Electronic address: markus.tilp@uni-graz.at.
Abstract
BACKGROUND: Recent ultrasound studies found increased passive muscle stiffness and no difference in tendon stiffness in highly impaired children and young adults with cerebral palsy. However, it is not known if muscle and tendon mechanical properties are already altered in highly functional children with cerebral palsy. Therefore, the purpose of this study was to compare the mechanical and material properties of the plantar flexors in highly functional children with cerebral palsy and typically developing children. METHODS: Besides strength measurements, ultrasonography was used to assess gastrocnemius medialis and Achilles tendon elongation and stiffness, Achilles tendon stress, strain, and Young's modulus in twelve children with cerebral palsy (GMFCS levels I and II) and twelve typically developing peers during passive dorsiflexion rotations as well as maximum voluntary contractions. FINDINGS: Despite no difference in ankle joint stiffness (P>0.05) between groups, passive but not active Achilles tendon stiffness was significantly decreased (-39%) and a tendency of increased passive muscle stiffness was observed even in highly functional children with cerebral palsy. However, material properties of the tendon were not altered. Maximum voluntary contraction showed reduced plantar flexor strength (-48%) in the cerebral palsy group. INTERPRETATION: Even in children with mild spastic cerebral palsy, muscle and tendon mechanical properties are altered. However, it appears that the Achilles tendon stiffness is different only when low forces act on the tendon during passive movements. Although maximum voluntary force is already decreased, forces acting on the Achilles tendon during activity appear to be sufficient to maintain typical material properties.
BACKGROUND: Recent ultrasound studies found increased passive muscle stiffness and no difference in tendon stiffness in highly impaired children and young adults with cerebral palsy. However, it is not known if muscle and tendon mechanical properties are already altered in highly functional children with cerebral palsy. Therefore, the purpose of this study was to compare the mechanical and material properties of the plantar flexors in highly functional children with cerebral palsy and typically developing children. METHODS: Besides strength measurements, ultrasonography was used to assess gastrocnemius medialis and Achilles tendon elongation and stiffness, Achilles tendon stress, strain, and Young's modulus in twelve children with cerebral palsy (GMFCS levels I and II) and twelve typically developing peers during passive dorsiflexion rotations as well as maximum voluntary contractions. FINDINGS: Despite no difference in ankle joint stiffness (P>0.05) between groups, passive but not active Achilles tendon stiffness was significantly decreased (-39%) and a tendency of increased passive muscle stiffness was observed even in highly functional children with cerebral palsy. However, material properties of the tendon were not altered. Maximum voluntary contraction showed reduced plantar flexor strength (-48%) in the cerebral palsy group. INTERPRETATION: Even in children with mild spastic cerebral palsy, muscle and tendon mechanical properties are altered. However, it appears that the Achilles tendon stiffness is different only when low forces act on the tendon during passive movements. Although maximum voluntary force is already decreased, forces acting on the Achilles tendon during activity appear to be sufficient to maintain typical material properties.
Authors: Annika Kruse; Andreas Habersack; Richard T Jaspers; Norbert Schrapf; Guido Weide; Martin Svehlik; Markus Tilp Journal: Int J Environ Res Public Health Date: 2022-09-15 Impact factor: 4.614
Authors: Qi L Xiong; Xiao Y Wu; Jun Yao; Theresa Sukal-Moulton; Nong Xiao; Lin Chen; Xiao L Zheng; Yuan Liu; Wen S Hou Journal: Front Neurol Date: 2018-10-16 Impact factor: 4.003