RESNA 26th International Annual Confence
Quantitative Evaluation of Orthotics Using Gait, postural stability, and Functional Measurement Instruments
This study investigated two types of ankle-foot orthotics (AFOs) and changes in motor performance by assessing gait, postural stability, GMFM and PODCI in children with spastic diplegic cerebral palsy. Both dynamic AFO's and hinged AFO'S improved gait parameters and postural stability metrics compared to barefoot. PODCI and GMFM scores did not detect changes between the braced and unbraced conditions. There were no significant differences in the gait parameters, postural stability metrics, or functional measurement scores between the two braces. These findings highlight the functional sensitivity of gait and postural stability in the study of rehabilitative orthotics intervention.
The standardized gross motor function measurement (GMFM) and standardized pediatric outcomes (PODCI) functional measures instruments have been validated in prior studies with excellent reliability in children with cerebral palsy (1). However, they may not be sensitive to subtle differences in balance, tone, or gait. Postural stability assessment and gait analysis are overlapping objective clinical tools that expand the evaluative scope of motor assessment (2,3,4).
The objective of this study was to determine whether postural stability assessment, gait analysis, and motor performance measures are effective in evaluating therapeutic management in children with cerebral palsy. We studied the role and effectiveness of two types of AFO's, the hinged AFO and the dynamic AFO, in children with cerebral palsy. Objective assessment of orthotics' effects on overall motor performance using these tools in a broadened functional evaluation approach may improve orthotics prescriptions.
Sixteen (16) children with a diagnosis of spastic diplegic cerebral palsy (7.5+ 2.9yrs.) 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. Postural stability, Gait, GMFM, and PODCI measurements were obtained at initial baseline, after each AFO trial, and at baseline between usage periods. Postural stability was monitored and analyzed from center of pressure (COP) signals. The COP signals were collected using two standard multi-axis force platforms (AMTI, Newton, MA) interfaced to the motion analysis system. A multi-camera (60 sps) Vicon Motion Analysis System was used to acquire temporal and kinematic data. Sections D and E of the GMFM were investigated to assess function-involving standing, walking, running, and jumping. Parents completed the PODCI, which addressed their child's walking ability, standing balance, brace fit, and endurance.
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. Hinged AFOs and dynamic AFOs both showed significant differences from barefoot walking in gait temporal and spatial parameters (p<0.05). Significant differences between braced and unbraced conditions were also found in kinematic parameters: peak ankle dorsiflexion, and peak ankle plantarflexion, knee stance peak flexion, knee swing peak flexion, hip stance peak flexion, and peak ankle plantarflexion moment, peak extension, knee swing peak extension, hip stance peak extension, hip swing peak flexion, peak power absorption, or peak power generation. There were no significant differences between braced and unbraced conditions in knee stance. Hinged AFOs and dynamic AFOs both showed significant differences from barefoot in COP normalized path length, COP normalized sway area, COP anterior-posterior (AP) sway mean frequency, and in the COP AP time-frequency proportionality factor (p<0.05) (TABLE II). The GMFM and PODCI metrics had insufficient sensitivity to detect differences children's function during barefoot and braced conditions. There were no significant differences in any gait parameters, COP metrics, or functional measurement scores between the two brace applications (p< 0.05).
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Gait temporal, kinematic and kinetic parameters and COP metrics improved toward normal values with bracing in patients with spastic diplegic cerebral palsy. 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 gait parameters, COP metrics, and 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. The study results clearly indicate advantages in function and ambulatory biomechanics with bracing. Significantly, these advantages are noted throughout the standardized and quantitative sections of the study. Specific differences in HAFO and DAFO applications are only minor with each treatment contributing significantly to functional improvement.