A Wearable "Balance Booster" - Stepping Closer to the Market
Phase: NA
Conditions: Distorted; Balance, Sensation Disorders, Peripheral Neuropathy, Neuropathy
Sponsor: RxFunction Inc.

PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
Introduction:  
Approximately 4.8 to 6.4 million Americans, comprising 30-40% of the U.S. diabetic population, exhibit 
symptomatic diabetic peripheral neuropathy (Harris, Eastman et al. 1993; Martyn and Hughes 1997; Apfel 1999). 
The prevalence may be as high as 50% in diabetics over 60 years of age. Up to 20% of the elderly population 
may be affected by peripheral neuropathies (PN) (Harris, Eastman et al. 1993; Richardson and Ashton-Miller 
1996). Epidemiological evidence has linked PN patients to an increased risk of falling (Richardson, Ching et al. 
1992; Richardson and Hurvitz 1995) and decreased stability while standing (Geurts, Mulder et al. 1992) and 
when exposed to external postural perturbations (Inglis, Horak et al. 1994). Consequently, there is a need for 
developing cost-effective interventions for improving mobility and balance to manage fall risk in the elderly 
(Rubenstein, Robbins et al. 1990; Studenski, Duncan et al. 1991; Province, Hadley et al. 1995) and other clinical 
populations (Richardson, Ching et al. 1992; Richardson and Hurvitz 1995). Walkasins™, a lower limb sensory 
prosthesis that replaces lost foot pressure sensation with vibrotactile feedback around the lower calf, can address 
this need. 
 
A growing body of research has investigated the use of vibrotactile feedback to enhance balance control following 
short-term use. Vibrotactile displays have been used successfully by the U.S. Navy to provide navigational cues 
that allow blindfolded pilots to control their aircraft (Rupert 2000; Rupert 2000). Sensory substitution devices to 
aid balance have provided auditory (Chiari, Dozza et al. 2005; Dozza, Chiari et al. 2005; Dozza, Chiari et al. 
2005; Dozza, Horak et al. 2007), electrotactile (Tyler, Danilov et al. 2003), and vibrotactile feedback (Wall, 
Weinberg et al. 2001; Wall, Merfeld et al. 2002; Wall and Weinberg 2003; Wall, Oddsson et al. 2004). More 
recent work has demonstrated the utility of vibrotactile feedback to improve postural control in patients (Horak, 
Dozza et al. 2009; Wall, Wrisley et al. 2009; Horak 2010; Wall 2010; Wall and Kentala 2010). None of these 
technologies, however, have been based on the measurement of foot pressure nor have they been intended to 
be worn on a continuous basis as a balance prosthetic device (Statler, Wrisley et al. 2007, Wall 2012). Current 
devices typically require a lab-engineer “on hand” to ensure functionality.  
 
Hypotheses and Objectives: 
 
The purpose of this study is to investigate the effect of 
Walkasins (Figure 1), a new user-friendly and robust 
external lower limb sensory prosthesis developed by 
RxFunction Inc. under NIH funding through a Small 
Business Innovative Research grant, on the balance 
and gait of persons with peripheral neuropathy who also 
experience balance problems. Walkasins provide 
gentle vibrations to the skin around the lower leg that 
reflect changes in pressure under the foot sole 
indicating the state of balance. The user learns to use 
these vibrations to control balance.  
 
We hypothesize that patients who use the Walkasins 
turned on will receive balance information that will 
improve their outcomes on gait and balance function, 
whereas patients who wear Walkasins turned off will not 
improve their outcomes on gait and balance function. 
Figure 1.  The Walkasins incorporate a thin shoe 
insert that measures changes in foot pressure during 
body sway. Vibrations provided to the skin on the 
lower calf represent new sensory information that the 
patient learns to use to improve balance.  

PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
Research Subject Recruitment and Inclusion/Exclusion Criteria: 
In this study, we will recruit 30 Veterans who have been diagnosed with peripheral neuropathy and who have 
self-reported balance problems. The following inclusion and exclusion criteria will be used for the study: 
Inclusion criteria 
 
Age: 18-90 years, male or female, 
 
Self-reported difficulty with balance, 
 
Diagnosed with sensory peripheral neuropathy (inability to perceive 10 g monofilament on the plantar 
surface of the foot at the big toe, 5th and 1st metatarsal), 
 
Functional Gait Assessment (FGA) <23 or fail on test 1, 2 or 3 on the 4-Stage Balance Test), 
 
Ability to understand informed consent,   
 
Living in the community, 
 
Shoe size between 8.5’’ (women’s 5) and 11.25’’ (men’s 12). 
 
Exclusion criteria 
 
Inability to perceive vibration stimulation on the lower calf (e.g., inability to sense vibration from tuning 
fork on the calf), 
 
Use of ankle-foot orthosis for ambulation,  
 
Open wounds on the foot or calf,  
 
Musculoskeletal or other neurological conditions that impact gait and balance (for example total joint 
replacement, moderate to severe Parkinson’s disease, stroke, etc.). 
 
Fliers will be posted in the physical therapy gyms at the Minneapolis VA Health Care System to advertise the 
study. Subjects who see the flier will be asked directly about their interest in the study. Subjects will also be 
recruited by screening patient data within CPRS using the ICD-10 code for peripheral neuropathy. Subjects 
found in the screening process will first be contacted via a letter, and then called by the PI or a member of the 
study team to see if they are interested in participating in the study. 
 
The study will involve one visit to the Minneapolis VA’s Physical Therapy Department and should last between 
2 to 3 hours. After arriving at the VA, the subject will go through the consent process with a member of the 
research staff. The consent process will happen within a private room in the Physical Therapy Department. Study 
staff will answer any questions related to the study and will ask the subject to answer questions that verify that 
they understand the study. After the consent process, the subjects will sign the appropriate forms indicating their 
consent to participate in the study and to allow the study team to use their data (explained in consent and HIPAA 
documents). After the consent process, the study staff will check the inclusion and exclusion criteria and will 
enroll the subject into the study if they meet all criteria. 
 
Research Methodology: 
After enrollment into the study, subjects will complete a health screening questionnaire and the Activities-specific 
Balance Confidence Scale: 
 
Health Screening Questionnaire – Subjects will fill out a screening questionnaire to assess common 
health issues related to neurological, musculoskeletal, cardiopulmonary disorders, and other systemic 
diseases as well as information on falls and currently used medications.  
 
 

PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
 
Activities-Specific Balance Confidence (ABC) Questionnaire – Powell and Myers (1995) developed the 
Activities-Specific Balance Confidence (ABC) Scale in an effort to detect levels of balance confidence in 
elderly persons (see Appendix). The ABC scale is a one-page questionnaire that asks questions about 
balance confidence when performing 16 different tasks. 
 
Subjects will then don the Walkasins device and complete baseline measures of the Functional Gait Assessment 
(FGA), 10 meter Gait Speed and 4-Stage Balance Test (see Figure 2 for protocol design).  During baseline 
testing, the Walkasins will be turned off. 
 
 
Figure 2: Cross-over study design. 
 
 
 
Functional Gait Assessment – The FGA is a reliable and valid measure of gait function related to postural 
stability and has been shown to be effective in classifying fall risk in older adults and predicting 
unexplained falls in community-dwelling older adults (Wrisley, Marchetti et al. 2004; Wrisley and Kumar 
2010). It has also been validated in stroke survivors (Lin, Hsu et al. 2010) and patients with Parkinson’s 
disease (Leddy, Crowner et al. 2011) and it has less flooring and ceiling effect than the Dynamic Gait 
Index (Lin, Hsu et al. 2010). The FGA includes a 10 item scale where each item is scored from 0 to 3 
(3=normal, 2=mild impairment, 1= moderate impairment, 0 = severe impairment). The maximum score is 
30. A difference of 8 points between measurement times is defined as the MCID in persons with vestibular 
disorders (Marchetti and Whitney 2010). 
 
 
10 meter Gait Speed – The 10m-walk (Perera, Mody et al. 2006) is routinely done in rehabilitation, has 
excellent reliability in chronic stroke patients (Hiengkaew, Jitaree et al. 2012) and physical therapists are 
well- trained in reliably performing this measure. In addition, gait speed has been found to be an important 
predictor of survival in older adults (Hardy, Perera et al. 2007), further emphasizing its importance as a 
clinical outcomes measure. Gait speed (10 meter walk using the middle 6 meters) will be assessed under 
two conditions: 1) instructed to walk at normal speed, 2) instructed to walk as fast as they can. A 
difference of 0.10m/sec is defined as the minimal clinically important difference (MCID) (Perera, Mody et 
al. 2006). 
 
Baseline Test 
30 subjects don 
device and are tested 
for FGA, Gait Speed 
& 4-Stage Balance 
with device OFF 
 Training 
15 subjects wear 
device and go 
through training 
with device ON.  
 Training 
15 subjects wear 
device and go 
through training 
with device OFF.  
 Testing 
15 subjects wear 
device and go 
through testing 
with device ON.  
 Testing 
15 subjects wear 
device and go 
through training 
with device OFF.  
Break 
Break 
 Training 
15 subjects wear 
device and go 
through training 
with device ON.  
 Testing 
15 subjects wear 
device and go 
through testing 
with device ON.  
 Training 
15 subjects wear 
device and go 
through training 
with device OFF.  
 Testing 
15 subjects wear 
device and go 
through training 
with device OFF.  

PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
 
4-Stage Balance Test – The 4-Stage Balance Test is part of the CDC recommended test protocol for 
balance function (STEADI, http://www.cdc.gov/steadi/pdf/4-stage_balance_test-a.pdf). It includes four 
gradually more challenging postures the subject is exposed to; 1) Stand with feet side by side; 2) Stand 
with feet in semi-tandem stance; 3) Stand with feet in tandem stance; 4) Stand on one leg. Subjects pass 
if they can hold the stance for 10 s and then move on to the next stance. A fail of 1, 2 or 3 indicates at 
risk of falling. In addition we will record time for each of the tests. 
 
Subjects will then be randomized into two groups according to their gait function (as measured by the FGA) and 
use of an assistive device (normal use is permitted, but not during the research study).  Group A will initially be 
trained and tested with the Walkasins turned on, then following a 60 minute break, will be trained and tested with 
the Walkasins turned off. Group B will initially be trained and tested with the Walkasins turned off, then following 
a 60 minute break, will be trained and tested with the Walkasins turned on. During testing, subjects will complete 
trials of Functional Gait Assessment, 10 meter Gait Speed and the 4-Stage Balance Test. All training and testing 
will be done by a physical therapist. 
 
Data Analysis: 
 
The primary outcome measures of this study include the Functional Gait Assessment, 10 meter Gait Speed 
test, and the 4-Stage Balance Test.  Using a between-group parametric statistical model, we will compare 
baseline measures from both groups to post-training outcomes following the first training session.  We expect 
that Group A (i.e., the group that first trained with the Walkasins on) will have a statistically significant 
improvement in functional gait and balance measures compared to Group B (i.e., the group that first trained 
with the Walkasins off).  We will also compare baseline measures to the post-training outcomes for Group A 
following the second training session (i.e., with the Walkasins off) to confirm that the 60 minute break between 
training sessions allowed for a washout effect of the first training.  If we are able to confirm a washout effect, 
we will pool our data (n=30) to compare the outcome measures from baseline and post-training with the 
Walkasins turned on. 
 
Risk to the Subjects and Approaches Taken to Minimize Risk: 
 
 
Use of device/administration of physical stimuli - The device being tested may distract the subject while 
walking and increase the risk of falling. To prevent falling, a spotter will walk next to the subject to help 
regain balance if a fall starts to occur.  
 
 
Video recordings and photographs - We will take videos and photos of the person using the Walkasins 
for use in publications and presentations. There is a risk that their identity will be disclosed by being 
recognized in these publications and presentations. We will collect their separate consent for use of 
pictures and video. 
 
 
Use of medical records - We may use the medical records to obtain information related to the cause of 
their peripheral neuropathy, for example, to be used in describing subjects in the study. There is a risk 
that study personnel may inadvertently see other information in their medical record unrelated to their 
neuropathy that may be private in nature. We will obtain HIPAA authorization for use of the medical 
records. 
 
 
 

PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
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The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
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PROTOCOL XXXX-X  
The Effect of Walkasins on Balance and Gait in People with Peripheral Neuropathy 
PI: Sara Koehler-McNicholas, PhD 
Version Date: April 5, 2016 
 
 
Appendix: Activities-specific Balance Confidence Scale