Evaluation of AFOs using Gait Analysis and Functional Treatment Measurement Instruments

S. Hassani; M. Ferdjallah; K. Reiners; C. Johnson; M. Carter; J. Chapman; M. Urban; J. Krzak; A. Caudill; A. Flanagan; P. Johnson; P. Smith; G. Harris; Shriners Hospital for Children Chicago, IL


Introduction

This study investigated two types of ankle-foot orthotics (AFOs) and changes in motor performance by assessing gait metrics, standardized gross motor function measurement (GMFM) and standardized pediatric outcomes (PODCI). Two types of AFOs, hinged (HAFOs) and dynamic (DAFOs) were applied in children with spastic diplegic cerebral palsy (DCP). Determining the correlation among these tools may impact the overall assessment methodology in this population.

Methods

Sixteen children with a diagnosis of spastic diplegic cerebral palsy (7.5+ 2.9 yrs.)were included in the study. Two types of AFOs were fitted for each subject. Subjects had one month to wear each AFO with a two-week baseline period between usage periods. Gait analysis, GMFM, and PODCI measurements were evaluated at initial baseline, after each AFO trial, and at baseline between usage periods. A multi-camera Vicon Motion Analysis System was used to acquire temporal and kinematic data (Figure 1 ).

Sections D and E of the GMFM were investigated to assess function-involving standing, walking, running, and jumping. Parents completed the Pediatric Outcomes Data Collection Instrument (PODCI), which addressed their child's walking ability, standing balance, brace fit, and endurance.

Results

Pearson correlation and two-sample comparison methods were used to determine correlation among the evaluation tools and to examine significant differences in mean response between the two braces. GMFM scores correlated strongly (r > 0.5) with PODCI physical function parameters (Tables I -II).

Table I. Analysis of Braces Using GMFM scores- *p<0.05
GMFM   Barefoot 1 Barefoot Barefoot HAFO
Scores   Vs. Vs. Vs. Vs.
    Barefoot 2 HAFO DAFO DAFO
Sections D 0.689 0.106 0.218 0.247
& E          
Table II. Analysis of Braces Using PODCI Scores *p<0.05
GMFM Scores Barefoot 1 Vs. Barefoot 2 Barefoot
Vs.
HAFO
Barefoot
Vs.
DAFO
HAFO
Vs. DAFO
Upper Extremity & Physical Function D.956 0.077 0.297 0.334
Transfer & Basic Mobility 0.576 0.222 0.752 0.736
Sports & Physical Function 0.129 0.506 0.322 0.502
Comfort/Pain 0.214 0.137 0.087 0.486
Happiness 0.858 0.882 0.095 0.112
Global Function & SvmDtoms 0.286 0.951 0.274 0.618

Of all normalized gait parameters, cadence, and walking speed correlated most strongly (r > 0.6) with GMFM scores. GMFM scores also correlated strongly (r > 0.5) with non-normalized stride length. Hinged AFOs and dynamic AFOs both showed significant differences from barefoot walking in gait temporal and spatial parameters (p<0.05). There were no significant differences in any parameters, between hinged AFOs and dynamic AFOs (p<0.05) (Table III).

Table III. Analysis of Braces Using Gait Analysis *p<0.05
  Barefoot 1 Vs. Barefoot 2 Barefoot
Vs.
HAFO
Barefoot
Vs.
DAFO
HAFO
Vs. DAFO
Cadence (steps min) 0.831 0.002* 0.009* 0.919
Walking speed (m/s) 0.412 0.022* 0.049* 0.878
Stride length (m) 0.577 0.001* 0.001* 0.349
Step length (m) 0.849 0.00l* 0.001* 0.171

Discussion

Gait Analysis parameters improved with bracing in patients with spastic Diplegic cerebral palsy, who were independent toe walkers. There were no significant differences between braced and unbraced conditions measured with either the GMFM (sections D & E) or the PODCI. There were no differences in any of the functional measures between DAFO and AFO braces. Interestingly, PODCI and GMFM lacked sensitivity to the difference in function between braced and unbraced conditions. Conversely, gait and temporal stride measures were very sensitive to these changes. These findings point to a method for improving the functional sensitivity while maintaining a relatively simple test. Further study of correlation among GMFM, PODCI, gait, and postural measures is also suggested.