Intraoperative experiments combined with gait analyses indicate that active state rather than passive dominates the spastic gracilis muscle's joint movement limiting effect in cerebral palsy. (August 2019)

• Record Type: Journal Article
• Authors: Kaya, Cemre S.; Bilgili, Fuat; Akalan, N. Ekin; Temelli, Yener; Ateş, Filiz; Yucesoy, Can A.
• Is Part Of: Clinical biomechanics. Volume 68(2019)
• Page Start: 151
• Page End: 157
• Publication Date: 2019-08
• Subjects: Cerebral palsy -- Spastic muscle -- Gait analysis -- Muscle force-knee angle characteristics -- Intermuscular mechanical interactions -- Epimuscular myofascial force transmission; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2019.06.005
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: In cerebral palsy, spastic muscle's passive forces are considered to be high but have not been assessed directly. Although activated spastic muscle's force-joint angle relations were studied, this was independent of gait relevant joint positions. The aim was to test the following hypotheses intraoperatively: (i) spastic gracilis passive forces are high even in flexed knee positions, (ii) its active state forces attain high amplitudes within the gait relevant knee angle range, and (iii) increase with added activations of other muscles. Methods: Isometric forces (seven children with cerebral palsy, gross motor function classification score = II) were measured during surgery from knee flexion to full extension, at hip angles of 45° and 20° and in four conditions: (I) passive state, after gracilis was stimulated (II) alone, (III) simultaneously with its synergists, and (IV) also with an antagonist. Findings: Directly measured peak passive force of spastic gracilis was only a certain fraction of the peak active state forces (maximally 26%) measured in condition II. Conditions III and IV caused gracilis forces to increase (for hip angle = 45°, by 32.8% and 71.9%, and for hip angle = 20°, by 24.5% and 45.1%, respectively). Gait analyses indicated that intraoperative data for knee angles 61–17° and 33–0° (for hip angles 45° and 20°, respectively) are particularly relevant, where active state force approximates its peak values. Interpretation: Active state muscular mechanics, rather than passive, of spastic gracilis present a capacity to limit joint movement. The findings can be highly relevant for diagnosis and orthopaedic surgery in individuals with cerebral palsy. Highlights: Intraoperative muscle forces and gait data of cerebral palsy patients were combined. Passive state forces of spastic Gracilis were measured for the first time. Active state forces in gait relevant positions exceeded four times the passive forces. Co-activation of other muscles did increase those active state forces significantly. The muscle has a capacity to limit joint movement in active state rather than passive.