Can pedobarography predict the occurrence of heel rocker in children with lower limb spasticity?
Anita J Mudge1, Morgan Sangeux2, Elizabeth A Wojciechowski3
1Paediatric Gait Analysis Service of NSW, Sydney Children's Hospitals Network (Randwick and Westmead), Sydney, New South Wales, Australia.
Background:
Pedobarography software calculates the centre-of-pressure trajectory in relation to the foot to quantify foot contact patterns. This study presents two new pedobarography measures using the centre-of-pressure trajectory to assess heel rocker.
Methods:
To validate these pedobarography measures against 3D gait analysis, emed®-x and Vicon Nexus gait analysis data were captured from 25 children aged 8-16 years (11 male) with unilateral (n = 18) and bilateral (n = 7) cerebral palsy or acquired brain injury. 3D gait analysis identified whether heel rocker was intact (n = 22 feet) or absent (n = 28 feet) based on centre-of-pressure at initial contact and the ankle kinematic curve between 0 and 2% of the gait cycle. Pedobarography measures calculated from the initial centre-of-pressure point were the distance to the heel (point of initial contact) and to the most posterior point of the trajectory (rollback), reported as a percentage of foot length.
Findings:
The median point of initial contact in limbs with an intact heel rocker was 9% (range 7-12%) and median rollback was 0% (range 0-0.2%), whereas the median point of initial contact in limbs with an absent heel rocker was 58% (range 8-78%) and rollback was 18% (range 0-40%). Point of initial contact is the more accurate method for predicting heel rocker, with a threshold of 14% of foot length identifying the correct heel rocker status in 94% of cases.
Interpretation:
Point of initial contact can assess heel rocker with high accuracy. Both point of initial contact and rollback provide sensitive information on foot strike pattern, enhancing the utility of pedobarography.
