Foot Progression Angle Modification: an Exploratory Six-week Telerehabilitation Intervention in People With Knee Osteoarthritis
Phase: NA
Conditions: Osteoarthritis, Knee
Sponsor: University of British Columbia

Official Title:  
Foot 
progression 
angle 
modification: 
an 
exploratory 
six-week 
telerehabilitation intervention in people with knee osteoarthritis. 
 
 
NCT Number: TBD 
 
Document Date: February 3th, 2021 
 

 
1 
Objectives 
The primary objective of this study is to examine the feasibility of conducting a gait modification 
intervention delivered using primarily a telerehabilitation model (video and/or teleconferencing). 
Specifically, we will assess 1) adherence and compliance to the program, 2) performance of the 
gait modification in laboratory and real-world settings, and 3) satisfaction with the program. We 
will also examine the effectiveness of the program by comparing 4) patient-reported outcome 
(e.g., pain and physical function) and 5) knee joint moments before and after the program. 
 
2 
Background 
2.1 
Knee OA is a costly public health problem impairing function and quality of life 
Globally, knee OA is a leading cause of disability [1] and several epidemiological studies have 
suggested that knee OA affects approximately 12% of the adult population [2-4]. In Canada, OA 
accounts for annual direct and indirect costs in excess of $27 Billion, stemming from health care 
services, treatments, and wage-related productivity losses [5]. Given the ageing population and 
concomitant increase in OA prevalence [6], the economic costs are also expected to rise. The 
large proportion of health care spending related to knee OA is allocated to surgical intervention 
(mainly knee replacement surgery), which only serves a small minority of patients with late-
stage disease [7]. Therefore, inexpensive treatments to manage clinical and structural progression 
of majority of people with early- and mid-stage knee OA are needed. 
 
2.2 
A modifiable risk factor of progression: knee joint load 
It is well accepted that excessive and/or abnormally distributed tibiofemoral (knee) joint load are 
key risk factors for the clinical and structural progression of knee OA [8]. While knee joint load 
is difficult to measure directly, quantitative gait analysis provides the tools to non-invasively 
estimate knee joint load [9, 10]. Over the last two decades, the knee adduction moment (KAM) 
has been established as a valid [9, 11] and reliable [12] outcome for estimating knee joint load 
during walking. The relevance of the KAM to knee OA is well accepted, primarily due to the 
relationships between elevated KAM magnitudes and worse clinical [13] and structural disease 
progression outcomes [14-18]. Elevated KAM magnitudes are also related to higher risks of pain 
during aerobic exercise [19-21], and aerobic exercises like walking are a core component in knee 
OA rehabilitation guidelines [22]. Therefore, lowering KAM may be a means of reducing the 
risk of disease progression, while also decreasing pain during activities such as walking. 
 
2.3 
Toe-in and toe-out walking to lower KAM and improve knee OA-related symptoms 
Several components of walking motion contribute to KAM magnitudes, one of which is the 
frontal plane ground reaction force lever arm [23], such that decreasing the lever arm can result 
in lower KAM magnitudes. The lever arm is affected by a number of walking characteristics, 
including the position of the foot in the horizontal plane during the stance phase [24]. The angle 
between the foot and the forward direction of walking, in the horizontal plane, is called the foot 
progression angle (FPA) where external rotation of the foot is “toe-out” while internal rotation is 
“toe-in”. Previous work has shown increased toe-out typically elicits lower KAM magnitudes 
later in stance, while increased toe-in elicits lower KAM magnitudes in early stance [25, 26]. 
Because of this relationship between FPA and knee joint load, and the protective effect of greater 
natural toe-out angles on structural disease progression [27], the FPA is a biomechanical target 
for knee OA management.  

 
Many studies to date have investigated the feasibility and biomechanical efficacy of modifying 
one’s FPA, both in healthy and knee OA populations [28]. Modifying FPA can be readily 
performed within a single practice session and can be guided by a variety of feedback modalities 
[29]. Through two clinical trials, our research group has demonstrated that increases in toe-out 
angle, practiced over ten to sixteen weeks, can result in clinically meaningful improvements in 
pain, physical function, and a reduction in KAM magnitude [30, 31]. Another three clinical trials 
have shown that increased toe-in angles, practiced over six weeks, can result in reduced knee 
pain and KAM magnitudes [32-34]. Despite the well understood biomechanical changes 
associated with FPA modification, and a growing understanding of the clinical response, FPA 
modification is not yet ready for clinical implementation.  
 
2.4 
Delivering gait modifications 
Several barriers exist that have limited the widespread implementation of gait modification for 
managing knee OA. Traditionally, gait modifications are taught using expensive laboratory 
equipment to provide the needed accurate feedback for instructing the new walking pattern [31-
33, 35]. Wearable sensor devices [36, 37] have also shown potential as a mobile solution to the 
generally inaccessible gait laboratory, but they are not widely available in the clinical setting and 
still need refinement in their application. Previously, we used a simple mirror placed in front of a 
treadmill to visually provide feedback to the learner, which was successful in teaching the toe-
out gait modification and is more clinically feasible that using motion capture technology [30]. 
However, this simple mirror strategy still requires in-person appointments and significant 
practice time, limiting accessibility and long-term feasibility. A solution that is clinically 
feasible, time efficient, and effective in improving the target outcomes is still needed. 
Importantly, in a post-COVID world, interventions that can be delivered remotely have gained 
increased importance. 
 
For over two decades telecommunication technologies have been explored as a means to deliver 
rehabilitation at a distance, which we will refer to as telerehabilitation [38]. These technologies 
can be used to complement face-to-face consultation and rehabilitation, or as the sole delivery 
method. In recent years, strong evidence has arisen demonstrating the effectiveness of 
telerehabilitation for treating musculoskeletal conditions, including knee OA [39]. In 2015, a 
non-inferiority trial found that telerehabilitation after total knee replacement surgery resulted in 
similar improvements in pain and physical function to traditional face-to-face physical therapy 
[40]. Patients and physical therapists alike found satisfaction in using this telerehabilitation 
approach [41]. Telerehabilitation has also shown promise for physical activity counseling [42] 
and exercise rehabilitation [43] of people living with knee OA. Again, patients and physical 
therapists expressed satisfaction with the rehabilitation and believe it was effective [44, 45]. This 
body of work demonstrates the feasibility and efficacy of telerehabilitation, particularly in 
populations with knee OA. Given this, there is a strong potential for using a telerehabilitation 
model to deliver gait modification to those living with knee OA.  
 
Previous in-person gait modifications for knee OA have used a specific kinematic or kinetic 
variable target that the learner must “aim” at. For example, our previous studies used 10 and 15 
increases to toe-out as the target, which we guided using visual feedback [30, 31]. While we had 
success with this strategy, there are two important limitations. First, a standard target may not be 

appropriate for some, limiting the efficacy of the treatment or creating frustration and eventual 
discontinuation. Second, it requires substantial practice using feedback to become proficient, 
which typically requires equipment and guided practice sessions. A more flexible approach 
would be to allow participants to self-select the modification they will perform, for example, 
they could select the amount of FPA increase. The primary advantage is a significantly reduced 
need for structured practice and feedback, lessening the burden on the clinician and patient. The 
disadvantage is that the patient may not self-select a large enough change in FPA to elicit a 
biomechanical response. Without the need for specific targeted practice, this self-directed 
strategy could help to facilitate the delivery of gait modification via a telerehabilitation model.  
 
2.5 
Monitoring performance and adherence 
To date, most gait modifications for knee OA have focused on knee loading and clinical outcome 
measures, spending little time examining the actual performance of the modification itself (i.e. 
how accurately the individual executes the gait modification). When performance has been 
measured, it has typically been done in laboratory settings, before and after a modification 
intervention, and always in reference to a specific target [30, 31, 46]. It is likely these 
performances in laboratory settings are subject to the Hawthorne effect, and do not necessarily 
reflect performance outside the laboratory. Unfortunately, the performance of the modification 
during daily walking activities (outside the laboratory environment) is currently unknown, which 
constitutes an important gap in our knowledge. As performing the modification during daily 
walking is arguably more important than doing so in the laboratory setting it is vital that we 
quantify performance in these settings.  
 
Given the potential of toe-in and toe-out walking modifications to benefit those with knee OA, it 
is important to address the limitations in our current knowledge before wider implementation can 
be expected. Our proposed study will be a pilot clinical trial focusing on self-directed FPA 
modification using a blended delivery (1 introductory session in person with the remainder via 
telecommunication). Performance and adherence to the gait modification will be monitored using 
a novel wearable sensor system co-designed by our research group and colleagues from 
Shanghai Jiao Tong University, Shanghai, China. This study will be the first knee-OA specific 
gait modification program delivered via telerehabilitation and will provide the first examination 
of performance and adherence to the program during daily walking activities. 
 
3 
Hypotheses 
3.1 
Primary hypothesis: 
H1:  We expect participants will adhere to the program by attending an average of 70% of the 
scheduled video or telephone appointments. Participants will report increasing compliance 
with the program week over week. 
H2:  Performance of the gait modification will improve over the six-week program. During real-
world walking and the laboratory-measured gait assessment at follow-up. participants will 
exhibit increased FPA magnitude (more toe-in or toe-out) and decreased variability 
compared to baseline FPA. 
H3: Participants will report feeling satisfied with the gait modification program. 
H4:  Significant improvements in pain and physical function will be reported between the 
Immediate Group and Delayed Group at week 6 of the study (Follow up for the Immediate 

Group and the secondary baseline for the Delayed Group). We also expect to see 
significant within-group improvements in pain and physical function in the Delayed Group 
when comparing their change from baseline to secondary baseline (control) with their 
change from secondary baseline to follow up (intervention). 
H5: Significant decreases in the knee adduction moment late stance peak and impulse will be 
exhibited between the Immediate Group and Delayed Group at week 6 of the study 
(Follow up for the Immediate Group and the secondary baseline for the Delayed Group). 
We also expect to see significant within-group decreases of the knee adduction moments in 
the Delayed Group when comparing their change from baseline to secondary baseline 
(control) with their change from secondary baseline to follow up (intervention). Knee 
flexion moment peak and impulse will not significantly increase for these same 
comparisons. 
 
4 
Methods and Approaches 
4.1 
Study design 
This delayed-control, randomized exploratory clinical trial will be a 6-week gait modification 
intervention, delivered using a telerehabilitation model to older adults with knee OA. Participants 
will be randomized to either the Immediate Group, where they will begin the 6-week 
intervention after completing the baseline assessment, or the Delayed Group, who will wait 6 
weeks before completing a new baseline (called a Secondary Baseline) before beginning the 
intervention. The intervention will consist of instructing the participants to increase their toe-in 
or toe-out angle during walking “as much as is comfortable”. Data will be collected both in 
laboratory settings (screening, baseline, follow up, and retention) as well as real-world 
environments (sensorized shoe and self-reported outcomes). Practice of the gait modification, 
after the initial introduction, will be delivered via videoconference (or telephone if necessary). 
The study will assess both the feasibility and effectiveness of gait modification delivered using a 
telerehabilitation model. A flow diagram of the study is included in Appendix A.  
 
4.2 
Participants 
A total of 30 participants with symptomatic and radiographically confirmed knee OA that is 
predominantly affecting the medial knee compartment will be recruited from the community to 
participate in this study. Participants will be randomized to either the immediate or delayed 
group (see Section 4.3.3 Randomization & Study Groups). 
 
4.2.1 Inclusion and Exclusion Criteria 
All eligible participants will: 1) be 50 years of age or greater, 2) exhibit signs of tibiofemoral OA 
(a score of ≥2 on the Kellgren and Lawrence (KL) grading scale [47]) predominantly in the 
medial compartment, 3) self-reported knee pain ≥ 3 / 10 on a numerical rating scale of pain 
(NRS; 0 = “no pain” and 10 = “worst pain imaginable”) during most days of the previous month, 
4) are comfortable walking intermittently for 30 minutes, and 5) fit into the available sizes of 
sensorized shoes (sizes spanning US women’s 5 to men’s 13). 
  
Exclusion criteria include: 1) any knee surgery or intraarticular injections within the past 6 
months, 2) a history of joint replacement surgery or high tibial osteotomy, 3) current or recent 
(within 6 weeks) corticosteroid injections, 4) use of a gait aid, 5) currently on a wait list for joint 

replacement surgery or high tibial osteotomy, 6) any inflammatory arthritic condition, and 7) any 
other conditions that may affect normal gait or participation in an aerobic exercise program.  
Additionally, potential participants will undergo an initial gait screening similar to a recent study 
[48] (details are outlined below – section 4.3.1-A), with the goal of identifying participants who 
are capable of reducing their KAM magnitude when FPA is modified. This gait screen will 
examine changes in knee load while walking with increased toe-in and toe-out, compared to 
natural FPA. Those who cannot elicit a reduction in KAM impulse ≥ 2% when FPA is changed 
by 10° in either direction will be excluded from the study as they would be considered non-
responders. 
 
4.2.2 Sample Size Calculation 
This study is primary focused on investigating the feasibility of delivering the gait modification 
using a telerehabilitation model and using wearable sensors to monitor performance. Past 
feasibility or pilot studies using gait modification for knee OA have included 10-20 participants 
[31, 32]. Indeed, it is also a feasible recruitment goal that our research group has achieved in 
previous pilot testing with this population [31]. The primary statistical test will compare the 
between-group difference in FPA at follow up using an analysis of covariance. With a large 
effect size expected (f = 1.0), power of 80%, alpha of 5%, and two groups with three covariates 
(two stratification variables and baseline FPA) we require a minimum of 14 participants. Given 
we are also interested in our secondary analyses, and to account for dropout, we will be 
recruiting a total of 15 participants per group for a total of 30.  
 
4.3 
Procedures 
4.3.1 Recruitment and screening 
Potential volunteers will be recruited via print and social media, and via our database of previous 
participants who have indicated interest in participating in future studies. Furthermore, 
participants who will be enrolled in a related study [H19-02323], and who are interested in 
participating in this study, will also be evaluated for eligibility. Interested volunteers will 
complete an online screening form followed by a telephone screen by the study coordinator (Ms. 
Krowchuk) to assess inclusion and exclusion criteria. Those deemed preliminarily eligible will 
be sent the consent form for review and any remaining questions will be answered by the study 
coordinator. The participant will then be invited to attend a gait screening appointment at the 
Motion Analysis and Biofeedback Laboratory in UBC Hospital. Informed consent will be 
obtained prior to any data collection at the screening session. 
 
4.3.1 A) Gait Screening Appointment – Data Collection: 
The assessment will consist of a thorough explanation of the study requirements, time 
commitments, and a biomechanical gait screen. The gait screen will be performed using motion 
capture to measure self-selected FPA and joint moments during walking on an instrumented 
treadmill. Fifty-four retroreflective markers will be placed on the skin over boney landmarks and 
7-high speed cameras (sample rate = 200 Hz) will track the positions of these markers in three 
dimensions. Additionally, two force platforms within the treadmill (sample rate = 2000 Hz) will 
measure ground reaction forces during walking.  The participants will walk for a total of 8-10 
minutes consisting of natural FPA, toe-out and toe-in FPA walking. The specific amount of 
change in FPA is not relevant, so long as a range of FPA magnitudes are recorded over the 
collected walking trials. These data will be used to determine whether the participant is a 

responder to FPA modification, and which direction (toe-in or toe-out) elicits the greatest 
response. 
 
The above approach for screening can determine which modification is more optimal, resulting 
in improved biomechanical outcomes [35, 49]. However, this method of gait analysis is not 
feasible in clinical settings. Therefore, we will collect a series of measurements related to knee 
joint loading (specifically the KAM) that are clinically-available with the goal of examining their 
ability to predict whether a participant will reduce their KAM magnitudes more using toe-in or 
toe-out modification. These measures will include body mass (kg), frontal plane tibial angle 
(degrees), and walking speed (m/s), which will be collected using a standard bathroom scale, 
gravity inclinometer, and timing gates, respectively [50]. These measures alone predicted 67% of 
the variance in overall peak KAM (body mass = 41% alone) [50], which is often the early stance 
peak. In addition, FPA will be measured using both a categorical and continuous method. While 
wearing wet socks, participants will walk over a 3m long piece of medical exam table paper 
taped to the floor. First, FPA will be visually categorized as neutral, small toe-in/out, large toe-
in/out by Ms. Krowchuk. Then, the foot imprint made by the wet socks will also be measured to 
extract the angle between the long axis of the foot imprint and the walking direction. These data 
will be compared with the quantitative gait screening assessment outlined above to A) predict 
KAM magnitudes and B) predict the direction of FPA change that would result in the largest 
reduction in KAM magnitudes. This examination is exploratory, with the goal of informing 
future clinical trials in settings without access to motion capture.  
 
4.3.1 B) Gait Screening Appointment – Data Analysis 
Immediately after data collection, the walking data will be processed in commercially available 
software (Visual 3D) and joint moments will be calculated using inverse dynamics. The KAM 
impulse (KAMi: area under the total KAM – time curve) and the FPA during 20%-80% of stance 
will be extracted. The reduction in KAMi for a given change in FPA will be linearly regressed 
and if a 2% reduction in KAMi is not achieved with a minimum of 10° of FPA change, the 
participant will be excluded. This cutoff value is based on our previous clinical trial which found 
average KAM reductions of 2% are possible with approximately 10° of toe-out. Additionally, a 
recent study used this same cutoff to screen participants for a KAM modifying treatment (lateral 
wedge insoles) in people with knee OA [48]. If a 2% reduction is achieved, the direction of FPA 
(either toe in or toe out) that elicits the largest reduction in KAMi for a given FPA change will be 
selected as the FPA modification to be used in the intervention to follow. These methods of 
screening for response to FPA change and personalizing the direction of FPA change were 
shown to improve biomechanical outcomes relative to a non-personalized approach [35, 49]. The 
results of the screening (whether the participant is eligible or not) will be communicated to the 
prospective participant with 24 hours. In total, this gait screening appointment will last 1.5 hours. 
 
After completing the screening appointment, the participants will be provided a pair of 
sensorized shoes (see section 4.3.2), charger, instructional booklet, and a walking diary to take 
home for a minimum of seven days. The instructional booklet outlines details of how to care for 
and use the sensorized shoes while at home and in the community. Notably, the participant will 
be instructed to turn the sensor on prior to beginning their walk, and off again after completing a 
walk. This will result in a single data file per walking bout. The wireless charging unit will be 
included to allow for charging the sensorized shoes as needed, much like a smart phone. An 

Figure 1. Sensor module construction and placement within the shoe. IMU, 
inertial measurement unit (accelerometer and gyroscope). 
online or printed self-report diary will be provided to track daily walking volume, walking times 
on each day, daily knee pain using an NRS (e.g. overall pain, pain during walking), non-walking 
exercise activities, and any adverse events related to their knees or walking. Additionally, an 11-
point numerical rating scale will be used to report weekly confidence in how accurately the FPA 
modification was performed (0 = “no confidence at all/unable to perform” and 10 = “completely 
confident”) and difficulty in performing the modification (0 = “not difficulty” and 10 = “most 
difficult/unable to perform”) for all diary weeks after week one. A minimum of ten-minutes of 
daily walking will be requested to ensure enough data for the analysis. 
 
C) X-ray Assessment 
Those meeting all criteria and who have passed the screening appointment will be referred to a 
local medical imaging clinic, either Greig Associates, Downtown Radiology, or UBC Hospital 
Radiology. Imaging will consist of a standing, semi-flexed postero-anterior radiograph of both 
knees. Osteoarthritic severity will be determined by the consensus of two independent assessors 
using the Kellgren and Lawrence (KL) grading scale [47]. The x-ray assessment will last 30 
minutes. 
 
4.3.2 Sensorized shoe details 
The sensor module is embedded in the shoe (Figure 1) and consists of a 3-axis accelerometer 
(signal range: ±4g), gyroscope (±500°/s), and magnetometer (±1200μT) which samples data at 
100 Hz. A previously published custom sensor fusion algorithm [51], programmed into a 
microcontroller, calculates the FPA in real time and stores it on a microSD card for later 
extraction. FPA is calculated based on five calculations: 1) orientation estimation of the sensor, 
2) gait event identification (heel strike and toe off), 3) trajectory estimation of the foot, 4) 
heading vector estimation, and 5) foot vector estimation [51]. Orientation was determined by 
integrating angular velocity and was then corrected based on accelerometer and magnetometer 
data. A zero-velocity detection algorithm determined heel strike and toe-off gait events. The foot 
and heading vector were computed based on orientation and trajectory estimation, and the FPA 
was calculated as the angular difference between the two vectors projected onto the horizontal 
plane. The magnetometer was pre-calibrated to determine an accurate magnetic north [52]. The 
sensorized shoe design and algorithm has been validated during treadmill [53] and over-ground 
walking [54] with excellent validity and reliability (absolute error = 1.7º and intraclass 
correlation coefficients > 0.9).  
 
4.3.3 Randomization and Study Groups 
Participants will be randomly 
allocated 
to 
either 
an 
Immediate Group or a Delayed 
Group after completing the 
baseline 
collection. 
The 
Immediate 
Group 
will 
be 
introduced 
to 
the 
gait 
modification and sent home 
with the sensorized shoes to 
begin 
the 
intervention 
as 
described below. The Delayed 
Group will schedule their 

secondary baseline for 6 weeks in the future and receive no intervention for that time period. 
After the 6 weeks of no intervention, the Delayed Group participants will return to the lab to 
receive their secondary baseline assessment and begin the intervention thereafter. We will use a 
variable block size stratified (KL grade and sex) randomization sequence with allocations sealed 
in envelopes, kept by Ms. Krowchuk, and revealed after the baseline data collection is complete. 
 
4.3.4 Data Collection 
An identical baseline, secondary baseline, follow-up , and retention  gait assessment (Table 1) 
will be conducted at the Motion Analysis and Biofeedback Laboratory in UBC Hospital. In a 
delayed-control study design the Delayed Group undergoes both a control condition and an 
intervention condition. For the Delayed Group, the control condition is assessed as the change 
from the baseline to the secondary baseline assessments, while the intervention is assessed as the 
change from the secondary baseline to the follow-up assessments. The Immediate group does not 
need the secondary baseline as they will only be undergoing the intervention condition, which is 
assessed as the change from the baseline to the follow-up assessment. 
 
These assessments will consist of questionnaires, a timed stair climb, and over-ground gait 
analysis. These sessions will be conducted by Ms. Krowchuk and Mr. Charlton. These 
assessments will last 1.5 hours each. 
 
Table 1. Timepoints for each data collection broken down by group. Each of the data collection 
appointments consists of questionnaires, a timed stair climb, and the gait analysis as described 
below. 
 
Week 0 
Week 6 
Week 10 
Week 12 
Week 16 
Delayed Group 
Baseline 
Secondary 
Baseline 
 
Follow up 
Retention 
Immediate Group 
Baseline 
Follow up 
Retention 
 
 
 
4.3.4 A) Questionnaires & the Timed Stair Climb: 
Baseline & Secondary Baseline Questionnaires:  
Q1: 
11-point numerical rating scale (NRS) depicting average knee pain over the previous 
week where 0 = “no pain”, 10 = “worst pain imaginable”  
Q2: 
Knee Injury and Osteoarthritis Outcome Score (KOOS) [55] 
Q3 
Pain Catastrophizing Scale [56] 
Q4: 
Arthritis Self-Efficacy Scale [57] 
Q5: 
Expected global rating of change in pain and physical function using a 15 point Likert 
scale where -7 = “a very great deal worse” and +7 = “a very great deal better” [58]. This 
will be administered at the baseline for the Immediate Group and the secondary baseline 
for the Delayed Group. 
 
Follow-up Questionnaires: 
Q1:  
11-point numerical rating scale (NRS) depicting average knee pain over the previous 
week where 0 = “no pain”, 10 = “worst pain imaginable”  
Q2: 
Knee Injury and Osteoarthritis Outcome Score (KOOS) [55] 
Q3: 
Perceived global rating of change in pain and physical function using a 15-point Likert 

scale where -7 = “a very great deal worse” and +7 = “a very great deal better” [58]. 
Q4: 
Satisfaction with the gait modification program and the telerehabilitation sessions using a 
7-point Likert scale where -3 = “extremely unsatisfied” and +3 = “extremely satisfied”. 
Q5: 
Convenience of telerehabilitation sessions on an 11-point NRS where 0 = “extremely 
inconvenient” and 10 = “extremely convenient”. 
Q6 
Difficulty of performing the gait modification during daily walking on an 11-point NRS 
where 0 = no difficulty/easy and 10 = most difficulty imaginable/unable. 
 
Retention Questionnaires: 
Q1:  
11-point numerical rating scale (NRS) depicting average knee pain over the previous 
week where 0 = “no pain”, 10 = “worst pain imaginable”  
Q2: 
Knee Injury and Osteoarthritis Outcome Score (KOOS) [55] 
Q3: 
Perceived global rating of change in pain and physical function using a 15-point Likert 
scale where -7 = “a very great deal worse” and +7 = “a very great deal better” [58]. 
Q4: 
Difficulty of performing the gait modification during daily walking on an 11-point NRS 
where 0 = no difficulty/easy and 10 = most difficulty imaginable/unable. 
 
At the baselines, medical history, anthropometrics (height, body mass etc.), age, and symptom 
duration will also be recorded by the assessor. At each assessment, a timed stair climb will be 
conducted as an objective measure of physical function. This will take place in a stairwell 
adjacent to the laboratory. The time taken to climb 12 steps (1 flight) will be recorded using a 
hand-held stop watch with the instruction to “climb as quickly, but safely as possible” [59]. Two 
repetitions of this test will be performed, and the fasted time will be used. 
 
4.3.4 B) Gait Analysis:  
A gait assessment will be performed at the baselines and follow up using identical procedures. A 
total of 54 reflective markers (45 lower limb, 9 upper limb) will be affixed to the skin bilaterally 
over key anatomical landmarks as is standard in our laboratory [26]. Fourteen high-speed 
cameras (sample rate = 120 Hz) will track the positions of these markers and two floor-
embedded force platforms (sample rate = 1200 Hz) will measure ground reaction forces. Five 
passes along the 10m instrumented walkway will be performed shod, wearing the sensorized 
shoes for standardization. Walking speed at the baseline assessment will be measured using two 
timing gates placed at a known distance along the walkway. At follow-up, participants will first 
complete five walking passes at a self-selected speed and then be constrained to walk within 
±5% of their baseline walking speed, due to the impact of walking speed on joint moments. After 
walking in the motion capture system, a lap of the hallways around our laboratory space will be 
performed while wearing the sensorized shoes (approximately 3 minutes total). This will provide 
a controlled measurement of FPA from the sensorized shoe for comparison with FPA measured 
during daily at-home walking. After the baseline appointment, the randomization will be 
revealed, and the participant will either be allocated to the Immediate Group or the Delayed 
Group. The Immediate Group will undergo the intervention condition (see section 4.3.5). 
Conversely, the Delayed Group will undergo the control condition first (see section 4.3.6), and 
then return for a secondary baseline, after which they would enter the intervention condition (see 
section 4.3.5).  
 
4.3.5 Intervention Condition: Gait modification 
The intervention will be delivered via telecommunication technology, except for an introduction 

to gait modification at the baseline appointment. Five telerehabilitation sessions will be 
conducted over the six weeks between baseline and follow-up appointments. These sessions will 
be conducted via a password protected official UBC Zoom videoconference application (Zoom 
Video Communication, Inc., USA) when possible, and a telephone when not. The study trainer 
will provide a meeting link and password ahead of the scheduled appointment via email. A 
review of the participants’ practice, perceived confidence in performing the gait modification, 
difficulty in performing the gait modification, daily pain levels over the day and during walking, 
and adverse events will be recorded by the study trainer. If possible, the participant will 
“demonstrate” their gait modification on video. No audio or video recordings will be kept, only 
notes taken by the study trainer during the session. The sessions will last between 15 and 30 
minutes. Outside of these sessions, participants will be expected to practice their gait 
modification in as much of their walking activity as possible. Practice performance will be 
monitored by the sensorized shoe. 
 
The direction of the gait modification (toe-out or toe-in) will be dictated by the gait screen 
(section 4.3.1-A), while the magnitude of the increase to FPA will be self-selected, with the goal 
of increasing “as much as is comfortable”. At baseline, the participant will be shown what their 
natural FPA looks like and what an increase FPA might look like, while being encouraged to use 
that as a reference when they are unsure if they have increased enough. The telerehabilitation 
appointments will serve to guide the participants in performing their modification. To assist 
participants with adherence and self-efficacy we will use, behaviour change techniques derived 
from physical activity and exercise interventions for knee OA during the telerehabilitation 
appointments [60]. These will include: 1) a discussion of the benefits related to performing the 
gait modification in their daily walking, 2) co-development of realistic goals for practicing the 
gait modification, 3) identification of potential barriers to practice and possible solutions, and 4) 
encouragement to self-monitor and use the diary to track progress. These techniques will be 
revisited at each telerehabilitation session with the study trainer to promote accountability, 
review successes and failures, and collaborate on adjusting goals or finding solutions to barriers. 
 
At-home walking between the baseline and follow-up data collection appointments will be 
monitored using the sensorized shoes. Participants will be asked to wear the shoes during as 
much of their daily outdoor walking activity as possible but to record at least 10 minutes per day 
(or 70 minutes per week). The sensor will be turned “on” immediately before beginning, and 
“off” immediately after completing a walk. One hour of charging will be needed every 2-3 days 
to maintain battery power. Apart from these two actions, the participant will not interact with the 
sensor in any other way. We will also provide instructions along with the shoes to remind 
participants how the sensor fits in the shoe and to troubleshoot any issues that may arise.  
 
While the sensorized shoes have the storage capacity to record the amount of data that could be 
collected over the six weeks, there is the possibility of an incident leading to data loss. To 
mitigate potential data loss, the study trainer will schedule a meeting with the participant at a 
mutually agreed upon location during weeks 2 and 4. During this meeting the study trainer will 
download data from the sensor; no discussion of the intervention or the participants’ progress 
will be discussed. 
 
4.3.6 Control Condition: Wait period 
Participants allocated to the Delayed Group at the baseline assessment will be sent home to 

undergo a 6-week waiting period. During these 6 weeks they will be asked to maintain their 
current level of activity. No data will be collected during this time. After the 6-week waiting 
period, the Delayed Group will return for a secondary baseline (identical to the original 
baseline). This will constitute the pre-post data collection for the control condition. They will 
then enter the intervention condition as described above in section 4.3.5.   
 
4.3.7 Data processing and analysis 
Marker-based motion capture data (as collected during the baseline and follow-up assessments) 
will be processed using commercially available software using standard techniques our research 
group has used in previous studies [26, 30, 61, 62]. Sensorized shoe data captured during the 
baseline and follow-up gait assessment and at-home or community walking will be processed 
using custom MATLAB scripts. 
 
4.4 
Outcome Measures 
4.4.1 Primary Outcome Measures 
The primary outcomes of this study are those related to feasibility. 
A) Modification Performance 
a. Change in FPA between baseline and the primary end point (6-week follow up). 
Measured via in-lab motion capture and the sensorized shoe during hallway 
walking. 
b. The change in FPA during at-home walking, comparing the mean baseline at-
home walking FPA with each walking bout (represented by a single data file on 
the sensor module) recorded during the intervention period. Measures of FPA 
variability will be calculated (variance, standard deviation, interquartile range) in 
addition to the proportion of steps taken with ≥7° of increase relative to their 
baseline FPA. Our previous results suggested 7º of change is required to elicit a 
statistically significant reduction in KAM magnitude [30, 31]. 
B) Adherence 
a. The total number of telerehabilitation sessions attended over the intervention 
period. Acceptable adherence is attending all 5 sessions. 
C) Compliance  
a. Self-reported confidence in performing the gait modification during at-home 
walking. Measured via the weekly diary on an NRS scale (0 = no confidence at 
all, 10 = complete confidence). Acceptable confidence ratings by week 6 are 
≥7/10. 
b. Self-reported walking time using the sensorized shoe during at-home walking. 
Measured via the weekly diary. Acceptable walking time is an average of 70 
minutes per week based on our instructions to walk a minimum of 10 minutes per 
day. 
D) Difficulty 
a. Self-reported difficulty in performing the gait modification on an NRS scale (0 = 
no difficulty and 10 = most difficulty imaginable). Acceptable difficulty by week 
6 is ≤4/10. 

E) Satisfaction 
a. Satisfaction with the gait modification program and the telerehabilitation sessions 
on a 7-point Likert scale where -3 = “extremely unsatisfied” and +3 = “extremely 
satisfied”. Scores of +2 or +3 will be considered “satisfied” and acceptable.  
4.4.2 Secondary Outcome Measures 
The secondary outcomes are related to the efficacy of the intervention and include the changes in 
knee OA related symptoms and joint moments, measured during the baselines, follow up, and 
retention appointments.  
F) Knee-OA related symptoms 
a. Pain will be assessed in several ways: 1) the change in score from baseline to 
follow up and retention of an 11-point NRS where 0 = “no pain at all” and 10 = 
“worst pain imaginable”, 2) change in weekly average knee pain on an 11-point 
NRS where 0 = “no pain at all” and 10 = “worst pain imaginable”, 3) the global 
rating of change score for knee pain on a 15-point Likert scale where -7 = “a very 
great deal worse” and +7 = “a very great deal better” [58]. The change from 
baseline to follow-up, and baseline to retention in the KOOS questionnaire 
subscales will also be assessed to quantify the multifaceted impact knee OA has 
on the individual [55]. The primary pain outcome will be the WOMAC pain 
subscale. 
G) Joint moments 
a. The KAM is both a valid [11] and reliable [12] estimate of knee joint load, and 
has important relationships with knee OA-related pain [19-21] and disease 
progression [14-18, 63]. We will examine KAM impulse and peaks (early and late 
stance) at baseline, follow up and retention. The knee flexion moment contributes 
to in vivo knee joint forces [10], is related to clinical progression [13] and pain 
[21], and in some cases may increase with changes in FPA [25]. For this reason, 
we will also examine the knee flexion moment peak and impulse at baseline, 
follow up, and retention. The KAM impulse is the primary joint moment 
outcome. 
 
 
 
 
 

5 
Appendix A 
 
Study Flow Diagram 
 

6 
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