Article Citation
Study
Objective/Purpose
(hypothesis)
Brief Background (why
issue is important;
summary of previous
literature)
Study Design
Target Population (dx,
acuity,
inclusion/exclusion
critieria)
Interventions (if
applicable):
(specificity of
interventions, ability to
replicate, frequency,
duration)
Outcome Measures
(relevant to purpose of
the study; reliable, valid,
clinical utility)
9.12.12
Online Journal Club- Article Review January 2014
Background/Overview
Mulroy SJ, Eberly VJ, Gronely JK, Weiss W, Newsam C J. Effect of AFO design on walking after stroke: impact of
ankle plantar flexion contracture. Prosthetics and orthotics international. 2010;34(3):277-292.
Purposes: (1) compare the effects of three different plastic AFO designs and shoes only on the gait parameters of
individuals following a stroke, and (2) identify whether a plantar flexion contracture could impact an individual’s
response to bracing.
Ankle foot orthoses (AFO) are frequently prescribed for patients with hemiplegia to enhance walking. Previous
studies have documented the effect of a rigid AFO on gait, however fewer studies have evaluated the more flexible
and articulating designs. Prior to this current study, no other study had looked into the effects of an articulating
orthosis with a dorsiflexion stop and a dorsiflexion assist on walking in this patient population. There was also a
need to incorporate specific patient presentations when considering appropriate AFO designs.
Methods
The study was a prospective crossover study of two cohorts in which subjects received all interventions in
random order (variable AFO). There were 30 subjects included, all of whom had a stroke.
Inclusion criteria: at least 6 months post cerebrovascular accident (CVA), either currently using or had experience
using an AFO recommended by a physician or physical therapist, and had maximal ankle dorsiflexion mobility
with knee extension that was equal to or greater than 0° or between 10 to 15° of plantar flexion measured
manually with a goniometer. Individuals were excluded if they required physical assistance to walk and/or had
self-selected walking speeds greater than 1.0 m/sec.
Each subject was fitted for three AFOs: (1) an articulated orthosis with a plantar flexion stop (PS) (2) an
articulated with dorsi-assist and dorsi-stop [DA-DS]; and (3) a rigid design AFO that limited both plantar and
dorsiflexion (Rigid).
Each participant was assigned to wear one of the three AFOs for 2 weeks. At the end of 2 weeks, a quantitative
gait assessment was completed. This was repeated for all three AFO’s. A gait assessment was also performed for
gait without an AFO at all 3 gait assessments.
Maximal isometric torques of ankle plantar flexors, ankle dorsiflexors, knee extensors, and hip flexors (paretic
leg ONLY) was assessed in a sitting position during two 5-second trails. Tensiometer recorded the maximal
isometric force of the hip extensors as well. Peak torque was calacuated as a percentage of gender matched
normal values. Spasticity of the calf was assessed with the Modified Ashworth Scale.
Stride Characteristics (speed, stride length, cadence)were recorded using a motion captured by a six-camera
Vicon Motion Analysis system with the central 6 meters of a 10 meter walkway being utilized for data acquisition.
Two trials of ambulation at a self-selected speed were collected for each orthotic condition. Motion was captured
using a six-camera Vicon Motion Analysis system to acquire three-dimensional sagittal plane motion for the
trunk, pelvis, and paretic lower extremity. Moment measures were compiled utilizing the fine-wire EMG
recordings, foot plates, footswitches and the motion capture video data. Ground reaction forces were recorded by
a force plate embedded in the center of the walkway. EMG recordings were taken at the tibialis anterior (AT),
soleus, and vastus intermedius (VI) during ambulation and for maximal voluntary contraction . Muscles lacking
sufficient volitional control to produce a significant electrical signal utilized a minimum threshold normalization
value to prevent irregular inflation of the EMG signals during ambulation.
Statistical Analysis
All ensemble average of all of all strides within each condition were averaged. For all dependent variables during
(statistics used,
walking, a two-way repeated ANOVA tested for differences among the four conditions (a significance level of
appropriate application) p<0.05 was used). If a statistically significant main effect of orthosis condition was identified, post-hoc
comparisons were conducted between each condition. A Bonferroni correction for multiple comparisons was
applied to both post-hoc comparisons and simple main effects tests.
Results
Enrollment/Subject
30 participants total: 9 with passive DF to neutral, 21 with limited DF
Characteristics
Mean age: 53.8yrs (range 36-75 yrs)
Gender: Males 23, Females 7
Left CVA: 8, Right CVA:15
Avg time since CVA: 25.3month (range 6-215)
No significant differences between groups were identified for any of the important subject characteristics
recorded.
Summary of Primary
Muscle Strength and Spasticity
and Secondary
-Decreased maximal isometric torques in the paretic leg for all muscle groups in both groups as compared
Outcomes (include
healthy norms.
aggregate and sub-The greatest muscle weakness was found distally on ankle plantar flexor and dorsiflexor muscles.
group findings if
-Participants in the neutral contracture group had stronger hip extensors.
reported); note results
-Spasticity in the ankle plantar flexors were similar among the two groups.
that were statistically
Stride Characteristics
significant; How many
Subjects in the neutral group walked faster, with longer strides and faster cadence than those in mod contracture
reached a level of
group regardless of the AFO condition.
clinical significance
There was a trend toward faster walking speed in the PS AFO compared to the Rigid AFO (Not Significant).
(exceed MCID if known); There were no effects of the type of AFO used on cadence or stride length in either contracture group.
Was there retention of
EMG
changes following
There was no differences between the groups in EMG intensity of the three muscles studied.
intervention (if studied) Walking in the PS AFO produced greater soleus EMG compared to the DA-DS AFO in both groups.
EMG intensity in the AT was lower in the PS AFO when compared to the shoes only and DA-DS conditions for both
groups. EMG intensity was not different between AFO conditions or groups.
Authors’ Discussion and Conclusions
Brief Summary of
All AFOs utilized in this study increased ankle dorsiflexion in swing phase and early stance phase. The PS AFO
Authors’ Main
reduced AT EMG activity, restricted ankle plantar flexion and knee flexion in loading and increased peak ankle
Discussion Points;
dorsiflexion and soleus EMG activity in stance. The Rigid AFO also restricted ankle plantar flexion and knee
Authors’ Conclusion
flexion in loading. Overall, individuals without a plantar flexion contracture benefit from an AFO that allows for
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Study Strengths
Study Limitations and
Potential for Bias
Applicability:
How will study results
impact PT management
of this patient
population?; List
suggestions for how to
implement changes in
your department to
integrate study findings
into patient care
dorsiflexion mobility in stance and will more easily tolerate an AFO with plantar flexion mobility in loading if they
have quadriceps weakness.
Reviewer’s Discussion and Conclusion
This study was the first of its kind to look into gait changes with different AFO’s as related to a patient’s ankle
mobility. The cross over design of the stude incorporated several AFOs commonly used.
Limitations related to kinetic analysis included only using the paretic leg for data collection, only using kinetic
variables in the sagittal plane and only utilizing two strides of kinetic data in each condition. Additionally the
normalization of the EMG data for muscles that did not demonstrate significant electrical activity during voluntary
contraction could have impacted the outcomes seen. Lastly, the small sample size was also listed as increasing the
risk of type II statistical error.
The results of this study apply to ambulatory patients with stroke. The setting most likely to apply utilize these
results is an outpatient or sub-acute rehab setting. The different types of AFOs used in this study could be easily
reproduced by a skilled orthotist given the quality of detail utilized by the authors.
Plantar flexion contractures may complicate an AFO prescription in people with stroke. This study provides
guidance into AFO selection for specific patients and provides insight into expected gait deviations from different
types of AFOs. Following a detailed movement analysis, a PT can use the results of this study to hypothesize what
type of brace will be most beneficial for the patient based on the reason for bracing (ie. Strength deficits,
contractures or utilizing available strength in a controlled scenario). Overall this study can be incorporated into a
program that would allow a clinician to prescribe more suitable AFOs to patients with variable presentations
following stroke.
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