Résumé:
Intrinsic gait variability (GV), i.e., fluctuations in the regularity of gait patterns between
repetitive cycles, is inherent to the sensorimotor system and influenced by factors such
as age and pathology. Increased GV is associated with gait impairments in individuals
with cerebral palsy (CP) and has been mainly studied based on spatiotemporal
parameters. The present study aimed to describe kinematic GV in young people with
CP and its associations with clinical impairments [i.e., passive range of motion (pROM),
muscle weakness, reduced selective motor control (selectivity), and spasticity]. This
retrospective study included 177 participants with CP (age range 5–25 years; Gross
Motor Function Classification System I-III) representing 289 clinical gait analyses [n = 172
for unilateral CP (uCP) vs. 117 for bilateral CP (bCP)]. As variability metrics, Root
Mean Square Deviation (RMSD) for nine lower-limb kinematic parameters and Gait
Standard Deviation (GaitSD) – as composite score of the kinematic parameters – were
computed for the affected (unilateral = uCP) and most affected side (bilateral = bCP),
respectively, as defined by clinical scores. GaitSD was then computed for the non/lessaffected
side for between leg comparisons. Uni- and multivariate linear regressions
were subsequently performed on GaitSD of the affected/most affected side with all
clinical impairments (composite scores) as independent variables. Highest RMSD were
found in the transverse plane (hip, pelvis), for distal joints in the sagittal plane (knee,
ankle) and for foot progression. GaitSD was not different between uCP and bCP
(affected/most affected side) but higher in the non-affected vs. affected side in uCP.
GaitSD was associated with age (p < 0.001), gait deviation index (GDI) (p < 0.05),
muscle weakness (p < 0.001), selectivity (p < 0.05), and pROM (p < 0.001). After
adjustment for age and GDI, GaitSD remained associated with muscle weakness (uCP:
p = 0.003, bCP: p < 0.001) and selectivity (bCP: p = 0.024). Kinematic GV can be
expressed as global indicator of variability (GaitSD) in young people with CP given the
strong correlation of RMSD for lower-limb kinematic parameters. In terms of asymmetry,
increased variability of the non-affected vs. affected side may indicate contralateral
compensation mechanisms in uCP. Notably muscle weakness (uCP, bCP) and selectivity
(bCP) – but not spasticity – were associated with GaitSD. Further studies need to explore
the clinical relevance of kinematic GV in CP to support the interpretation of clinical gait
analyses and therapeutic decision-making.
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