Reliability outcomes and inter-limb differences in ankle joint stiffness in children with unilateral cerebral palsy depend on the method of analysis

• Published in: Journal of electromyography and kinesiology 2019-12, Vol.49, p.102353-102353, Article 102353
• Main Authors: Boulard, C., Gautheron, V., Lapole, T.
• Format: Article
• Language: English
• Subjects: Ankle Joint - physiopathology; Cerebral Palsy - physiopathology; Cerebral palsy-ankle joint-stiffness-reliability; Child; Female; Functional Laterality; Humans; Life Sciences; Male; Muscle Contraction; Muscle Strength; Muscle, Skeletal - physiopathology; Myography - methods; Myography - standards; Range of Motion, Articular; Reproducibility of Results; Torque
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/j.jelekin.2019.102353

Children with cerebral palsy (CP) present increased passive ankle joint stiffness, measured as the slope of the torque-angle curve relationship. However, large discrepancies in results exist among studies, likely because of various methodologies used. The purpose of this study was to determine the influence of different calculation methods on the outcomes and their inter-session reliability in children with unilateral CP (UCP). Thirteen children (mean age: 9.8 years) with spastic UCP underwent passive ankle mobilization at 2°/s on both legs using a dynamometer, on two occasions separated by one week. Passive ankle joint stiffness was calculated as the slope of the torque-angle curve using linear regression on three different relative ranges of torque (i.e. 30%–100%, 20–80% and 50–90% of maximal torque for method 1, 2 and 3, respectively) for both the paretic and non-paretic legs. Inter-session reliability was significantly lower on paretic leg (mean CV = 13.8%, ICC = 0.62) when compared to non-paretic leg (mean CV = 6%, ICC = 0.85), and method 3 presented lower reliability outcomes (mean CV = 11.7%, ICC = 0.75) than methods 1 (mean CV = 7.5%, ICC = 0.78) and 2 (mean CV = 6.6%, ICC = 0.79). Paretic values (0.24 Nm/°) were not different from the non-paretic leg (0.25 Nm/°), although significantly higher when considering the same angular sector (0.18 Nm/°). Passive ankle joint stiffness measurement can be reliably performed in children with UCP using method 1 and 2 while method 3 should be avoided. The non-paretic leg may be used for comparison with the paretic leg when taking into account differences in maximal dorsiflexion angle between legs. ClinicalTrials.gov Identifier: NCT02960932.