Effects of Two Different Types of Ankle Foot Orthoses on Gait Outcomes in Patients With Subacute Stroke.

Introduction: Stroke is a leading cause of death and disability in the world today. About 795,000 people are diagnosed with stroke yearly in the United States. The annual cost of stroke from medical services and disability in our nation is $ 38.6 billion dollars. Gait rehabilitation is an important aspect of neurorehabilitation with focus on attaining the most functional and symmetrical gait to prevent falls from faulty gait mechanics, and to prevent sedentary life styles and associated comorbidities. Ankle foot orthoses (AFOs) are commonly prescribed in patients with stroke to address ankle and knee instabilities and to restore a normal and safe walking pattern.The effectiveness of AFOs on various gait parameters has been reported in patients with stroke, but mostly during the chronic stages of recovery. Systematic analyses have shown that use of various types of ankle foot orthoses improve walking impairments and balance, reduce energy costs, and improve knee and ankle kinematics in people in the chronic stage of stroke recovery, greater than 6 months since the onset of stroke. It is reported that the majority of the gait improvements occur within the first 6 months following the onset of stroke. However, a limited number of studies have investigated the effects of AFOs within six months of stroke onset.

Three reported studies have investigated the effects of using an AFO compared to not using an AFO within 6 months following onset of stroke. Rao et al found that the use of an AFO significantly improved gait velocity, cadence and step length on the affected and unaffected side. Hyun et al. found that using an AFO significantly improved VO2 peak and 6 minute walk test scores . Carse et al showed significant improvement in walking velocity, average step length and cadence with use of AFO. There is only one reported study which looked at the effects of using two different types of AFOs during the subacute stage of stroke, less than 6 months following onset. Results of this study showed that gait speed and knee and ankle control were significantly higher in the Chignon AFO group compared to the polypropylene AFO group. Additionally, participants in the Chignon AFO group had significantly lower spasticity than those in the polypropylene AFO group.

In a recent case series report, investigators observed that using a custom Double Adjustable AFO during the early stages of recovery after stroke resulted in more typical muscle activation patterns, gait endurance and velocity, and near normal symmetry during gait without an assistive device or an AFO in three participants. The use of this type of AFO for gait rehabilitation following stroke in the subacute stages has not been thoroughly studied.

Statement of the Problem Patients with stroke resulting in hemiparesis and foot drop are affected by gait impairments such as poor symmetry, decreased velocity, and decreased endurance. AFOs have been shown to be an effective intervention for improving gait parameters in individuals who are in the chronic stage of stroke recovery. Although, the majority of gait improvements occur within six months of stroke, the effect of early bracing with different types of AFOs on gait outcomes has not been investigated thoroughly.

Purpose of the study:

The purpose of this study will be to identify whether patients in the subacute stage of stroke, who demonstrate foot drop, will have better gait outcomes when using a Double Adjustable AFO, or a Posterior Leaf Spring AFO. A secondary purpose will be to determine whether one week of practice significantly changes gait outcomes with either of the AFO conditions.

Research Hypotheses

The research hypotheses of this study are as follows:

1. There will be a difference in gait endurance measurements, gait symmetry measurements and gait velocity measurements at baseline when using custom Double Adjustable AFO compared to a PLS AFO in patients in subacute stage of stroke.
2. There will be a difference in gait endurance measurements, gait symmetry measurements and gait velocity measurements after one week of practice when using custom Double Adjustable AFO compared to a PLS AFO in patients in subacute stage of stroke.
3. After a week of practice, there will be a difference in gait endurance measurements, gait symmetry measurements and gait velocity measurements compared to baseline measurements, when using either custom Double Adjustable AFO or a PLS AFO in patients in subacute stage of stroke.

Participants Twenty participants over the age of 18, of any gender and ethnicity, diagnosed with first time unilateral stroke, 4 - 20 weeks post-stroke onset, resulting in hemiparesis with foot drop will be recruited. The number of participants was estimated based on previously reported studies. Hyun et al found significant differences in gait endurance measured by 6MWT when using AFO compared to using no AFO with 15 participants in a similar study. In another study by Carse et al, gait velocity and gait symmetry were found to be significantly better with 8 participants.Therefore, for our study, the potential participant number was projected as 20.

Participants will be recruited through a sample of convenience from Baylor Institute of Rehabilitation locations and through word of mouth. The physical therapists at these locations will be given a brief description of the proposed study and will be asked to screen for potential participants. Participants who meet the inclusion criteria and possess none of the exclusion criteria will be asked to volunteer for the study. Each participant will read or be read their rights as human subjects and asked to sign the informed consent approved by the Institutional Review Boards of both Baylor Health Care System and Texas Woman's University prior to enrollment in this study. A Mini Mental State Examination (MMSE) will be performed to determine whether the participant has the cognitive ability to sign the informed consent. Participants will be scheduled to do data collection on the day they receive their custom double adjustable AFO at Baylor Institute for Rehabilitation, Frisco location.

Procedures:All measurements will be obtained from each participant during three testing sessions and by only one researcher to avoid inter tester reliability issues. On the first measurement day, the primary investigator will collect demographic data including age, height, weight, leg length measurements on each side, and Fugl-Meyer Lower Extremity Assessment of sensorimotor function. Then the gait outcomes will be measured using one of the two AFO conditions in random order. The participant will select the order of AFO condition by drawing out of a hat. Randomization without replacement will be used. Once the order of AFO wearing has been determined, data will be collected in the randomly selected order. Participants will be allowed to use any type of assistive device of their choice, but the same device will be used for all conditions.

First, the 6MWT will be administered with the participant wearing the first randomized AFO. Participants will be asked to ambulate as far as possible in 6 minutes at a self-selected walking velocity through a well-lit indoor corridor. A five minute seated resting will be provided. Next, gait symmetry and gait velocity measurements will be obtained using the GAITRite system. Participants will be given a practice trial walk prior to beginning of the testing. Participants will be asked to walk at their comfortable self-selected walking velocity along the walkway. They will begin walking three meters from the start of the walkway and will stop walking two meters past the end of the walkway. The beginning and end of the walking area will be marked with red tape for visibility. The verbal instruction will be "Please walk from this red line to that red line at your comfortable speed safely". A second personnel will be walking close to the participant outside of the walkway to ensure safety. After a five minute sitting break, participant will be asked to walk as fast as they can safely. The verbal instruction will be "Please walk from this red line to that red line as fast as you can safely". The GAITRite system will be able to capture both gait symmetry and gait velocity measurements with the same walk. Three trials will be performed of the self-selected velocity walk and fast paced velocity walk. The calculated mean of the three trials will be used for data analysis. After a 10 minute seated rest break, the second AFO condition will be used and measurements will be repeated in the same order described above.

To assess the effects of practice on the gait measures, AFO's will be randomized for practice. Participants will be randomized for which AFO they will wear first. Then the participant will be provided with the selected type of AFO to practice with for the following week using a prescribed wearing schedule. At the end of the one-week practice time, the primary investigator will obtain the same measurements obtained at baseline with the participant wearing the type of AFO that was used to practice the week before. The same testing conditions and order of testing that were used at baseline will be employed. Once measurements are completed, the participant will be provided with the second type of AFO and will be asked to wear for one week using the same prescribed wearing schedule as before. Final measurements will be taken after completion of the one-week practice using the second type of AFO with the same testing conditions and orders. At the conclusion of testing each participant will be asked which AFO they will prefer to use.

Data Analysis : Descriptive statistics will be calculated for all demographic data including age, height, weight, time since onset Fugl Meyer lower extremity assessment score and AFO preference. Differences in gait endurance will be analyzed using a 2x2 repeated measures ANOVA Differences in gait symmetry, and gait velocity between the two AFO conditions and two practice conditions will be analyzed using two separate 2x2 repeated measures MANOVA. If assumption of sphericity is not met, Greenhouse-Geisser statistic will be used. An alpha level of .05 will be used to determine significance of differences, with a Bonferroni correction applied as needed to protect against Type I error.