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A cross sectional study investigating dynamic balance when stepping to targets in children with cerebral palsy
Rachel Rapson1, Jos M Latour2, Bernie Carter3
1School of Health Professions, Faculty of Health, University of Plymouth PL6 8BH, UK; Children and Family Health Devon, Torbay and South Devon NHS Foundation Trust, Devon TQ1 7AA, UK.
Insights
Children with Cerebral Palsy (CP) exhibit smaller anticipatory postural adjustments (APAs) during stepping tasks, impacting their dynamic balance. These smaller APAs are linked to reduced movement quality and may be influenced by muscle strength and length.
Area of Science:
- Biomechanics
- Neuroscience
- Pediatrics
Background:
- Children with Cerebral Palsy (CP) often display altered anticipatory postural adjustments (APAs) during gait initiation.
- These APAs are crucial for maintaining dynamic balance during tasks like stepping.
Purpose of the Study:
- To investigate how APAs are affected in children with CP during stepping to precise targets.
- To determine if children with CP can modulate APAs when stepping medially or laterally.
- To explore the relationship between APAs and measures of symptom severity, movement quality, and impairment.
Main Methods:
- Children with CP and typically developing (TD) children performed a stepping task to medial and lateral targets.
- Center of pressure (COP), pelvic, and foot motion were tracked using 3D motion analysis and a force plate.
- APAs were assessed before leading leg lift-off, and stepping error was calculated. Clinical measures included GMFM, QFM, hypertonia, and strength.
Main Results:
- Children with CP had 20-30% smaller medio-lateral APAs compared to TD children.
- Children with CP showed reduced ability to modulate APAs for medial and lateral stepping targets.
- Medio-lateral APA size correlated with movement quality (QFM, GMFM) and hip abductor strength. Antero-posterior APAs were smaller when stepping with the non-paretic leg.
Conclusions:
- Children with CP demonstrate diminished medio-lateral APAs, particularly when stepping towards medial targets.
- APA limitations in CP may be associated with proximal muscle strength and gastrocnemius muscle length.
Background:
Children with Cerebral Palsy (CP) have altered anticipatory postural adjustments (APAs) during gait initiation. These APAs may affect dynamic balance in tasks such as stepping.
Research Questions:
How are APAs in children with CP affected during stepping to precise targets? How do children with CP modulate APAs when stepping to medial and lateral targets? What is the association between APAs and symptom severity, movement quality and impairment profile?
Method:
Children undertook a stepping task to laterally and medially placed targets with either leg, in a randomised order. Movement of the centre of pressure (COP) and markers at the pelvis and foot were measured via a force plate and 3D motion analysis. Motion of the centre of mass (COM) was estimated via pelvic markers. APAs were assessed prior to leading leg lift-off in medio-lateral and antero-posterior directions. Stepping error was calculated. Baseline characteristics of children with CP included Gross Motor Function Measure (GMFM), Quality Function Measure (QFM), leg muscle hypertonia (Tardieu test) and strength (manual dynamometry).
Results:
Sixteen ambulant children with CP (12.2 years ± 2.2) and 14 typically developing (TD) children (11.6 years ± 2.9) were assessed. In children with CP, APAs in the medio-lateral direction were 20-30% smaller. Children with CP were less able to modulate their APAs with steps to medial and laterally placed targets, than TD children. Medio-lateral COP motion was associated with movement quality assessed by QFM subsections, GMFM (correlation coefficient r = 0.66-0.80) and hip abductor strength (r = 0.75). Antero-posterior APAs were significantly smaller when stepping with the non-paretic leg in children with CP. APA size was positively related to the length of the contralateral, paretic gastrocnemius (r = 0.77). Stepping error was higher in children with CP and inversely correlated to the size of the medio-lateral APA.
Discussion:
Children with CP show smaller medio-lateral APAs especially when stepping to medially placed targets. APA size may be limited by proximal muscle strength and gastrocnemius length.
