Recovery Track(er)
Biomedical Engineering
Senior Design Project
Levy Amar, Pravin Chottera, Kate Millington, Pooja Shaw
Recovery Track(er)
1
Design Problem

The ankle bears the most weight per unit area than any other place
in the body.



Despite prevalence of injury, and thus treatment, there are few
quantitative ways to monitor the recovery process or gauge the
efficacy of treatment.
Currently, monitoring of patient recovery requires the patient to
come into a physical therapist on a regular basis and perform a
series of weight baring and gait analysis test.


Ankle injury, specifically ankle sprains, are the most prevalent injury
during recreational activity.
These tests only estimate normal function and do not provide an in situ
measure.
Furthermore, traveling to the clinic on a regular enough basis is
inconvenient for the patient.

Patients frequently miss appointments if they are required to go on a
regular basis for a long period of time, impeding their recovery process.
Recovery Track(er)
2
Design Brief

We propose to build a device which will help patients track their
rehabilitation process after ankle surgery or series injury.



The collected information will be relayed back to a central
computer where the collected data will be compared to normal
values. (i.e. the values from the ‘healthy’ leg)


The device will be small enough to be comfortably worn in the user's
shoe without altering normal gait or causing further injury.
It will collect information about force distribution both spatially and
temporally.
The original force data, as well as the quantitative comparison, will be
displayed in an easily accessible interface.
This device can be sent home with patients receiving physical
therapy and allow them to collect data at their convenience in their
own home. They can then send this data to their medical specialist
to be evaluated.
Recovery Track(er)
3
Demographics
Four Modalities of Ankle Injury
Ligament- Ankle Sprains



75% of all ankle injuries
Most common recreational injury
$2 billion annually in the U.S.(AAOS)
Bone


LIGAMENT
Ankle Fracture
Caused by rolling ankle inward or outward
Ranges from avulsion to shattering
Treated by immobilization or surgery depending on
the severity of the fracture.
Tendon-
BONE
TENDON
JOINT
Achilles Tendon
Rupture

Sudden onset: a ‘pop’

Only treatable by surgery requiring 6 to 12 month
recovery
Joint-
Arthritis
Osteoarthritis

Wearing away of cartilage lining joint

Due to prior joint injury or ageing
Rheumatoid Arthritis

Inflammation of the joint

Surgically treated by fusion, clearing, or replacement
Recovery Track(er)
4
Demographics
User & Customer
Who is the User?
Patients recovering from ankle surgery or
serious injury
Use outside the clinic in the patient’s home
Results sent to attending physician or physical therapist
Who is the Customer?
Hospitals or Physical Therapist Offices
Loaned to patients as needed
Used to track individual patient progress
Can also be used to evaluate treatment and recovery methods
Recovery Track(er)
5
Competing Products
1) TekScan
•In office use
•One time output for diagnosis
•No tracking of data
2) Nike+ iPod Sport Pack
•Wirelessly transmits music from
iPod to Nike shoe
•Audio signal only
•Non-medical use
•Circuit board on Recovery
Track(er) is in the same location as
the receiver on the Sport Pack
Recovery Track(er)
6
Constraints and Specifications




Cost
Control
To be widely accessible and usable
the device must be inexpensive to
produce and readably useable with
little to no training
Device must provide accurate data
on the recovery process without
causing further injury to the patient,
impeding their recovery, or altering
normal function. Since osteoarthritis is
a major cause of ankle injury, it is
important that our device be
comfortable and accessible to the
elderly population.
Consistency
Comfort
Our device must also be in compliance with FDA regulations specified under
Section 888.1500, regarding the electrode lead wires and patient cables used in
an orthopedic diagnostic device.
Recovery Track(er)
7
Project Design Ideas
Parts 1, 2, & 3
Send Parts 1&2 home with the patient:
Part 2: Data Acquisition
Gathering and Storing the Data
Part 1: Insole
Acquiring the Data
Send the data in to physical therapists
at regular interval for Part 3- evaluation
of progress:
Part 3: Signal Analysis/ Data Output
Display of Data in an Easily Accessible Interface
Recovery Track(er)
8
Part 1: Insole
Acquiring the Data
1) Fixed Pressure Sensors
A flexible insole covered in
commercially available standard
pressure sensors
• Sanitation? Different disposable
covers? Individual patient sensor
boards?
• Different Sizes? Limited by sensor
size or cost?
• How many sensors do we need?
Statistical and physical significance?
Recovery Track(er)
9
Part 1: Insole
Acquiring the Data
2) Sensor Envelope
Disposable insole ‘envelops’ into which
individual sensors are placed.
• Allows for easy sanitation and size
differences.
• Requires training of user. Too
complicated to put together?
• Will sensors be secure enough to
record accurate data? How will we
secure in pockets?
• How will we wire the sensors to
allow easy insertion without tangling?
Recovery Track(er)
10
Part 1: Insole
Acquiring the Data
3) Piezoelectric Film
A texurized flexible insole overlaid with
PVDF (a piezoelectric film which acts as a force
sensor and can detect strain with a linear
output)
• Customizable to physiological sites
and sizes.
• Will texturized sole interfere with
healing or natural gait?
• How will we read output?
• Capacitive interference from wiring?
Is there a finite amount of possible
data collection due to time resolution
or PVDF properties.
• No precedent of use
Recovery Track(er)
11
Part 1: Insole
Acquiring the Data
Recovery Track(er)
12
Part 2: Data Acquisition
Gathering and Storing the Data
1) Circuit Board
Our Black Box
• How many sensors can we put in one
microprocessor?
• What speed etc are we going to
need?
• How big of a memory chip?
• Power Source? Batteries?
• How will we upload to the
computer? UBS? Bluetooth? Will this
add weight or bulk? Cost?
Recovery Track(er)
13
Part 2: Data Acquisition
Gathering and Storing the Data
2) Ankle or Belt Strap
“Black Box” attaches around ankle or clips to
belt
• Ankle allows direct wiring to sensors. Belt
would need wireless?
• Shape? Weight?
• Safety?
• If wired - how could we do it cleanly
• If wireless - how would we do it? Where could
we upload it to?
Recovery Track(er)
14
Part 2: Data Acquisition
Gathering and Storing the Data
3) Pouch
The “black box” is in a pouch that can be
attached to the shoelaces of the shoe
• Allows direct wiring to sensors. How can
we wire it cleanly?
• Could also be wireless.
• Shape? Weight? Will adding too much to
foot cause strain?
• Safety?
• Is pouch enough to protect circuit inside?
• How will memory and power source be
accessed?
Recovery Track(er)
15
Part 2: Data Acquisition
Gathering and Storing the Data
Circuit board can either go
into pouch on shoe or an
ankle strap
Recovery Track(er)
16
Part 3: Signal Analysis/ Data Output
Display of Data in an Easily Accessible Interface
1) Complete Data Set
Graphical output of entire data set
• Too much information to be useful? Will
depend on intended user
•Can show everything collected and leave
bias to the interpreter.
•Leaves user to do all of analysis and
qualitative tracking of recovery by using
side by side comparisons to normal
• Could have option for differential (see
next idea)
Recovery Track(er)
17
Part 3: Signal Analysis/ Data Output
Display of Data in an Easily Accessible Interface
2) Differential
Graphical output of differential data set
• Only shows areas different from ‘normal’
image
• Distills data into important areas for
further investigation.
• Over simplification?
• Does this take into account interactions
between different parts of the foot
• How would we set the threshold for
significant differential?
Recovery Track(er)
18
Part 3: Signal Analysis/ Data Output
Display of Data in an Easily Accessible Interface
3) Numerical Output
Output is % improvement from last use- progress
back to normal
Either: Poor, Fair, or Good Progress
% Improvement
• All analysis done behind the scenes.
• Requires little training to use - user doesn’t need
to know anything about analysis only gets answer
they need.
• Too little information?
Good
Fair
Poor
• Too much behind the scenes opens up program
for generalization induced mistakes
Recovery Track(er)
19
Part 3: Signal Analysis/ Data Output
Display of Data in an Easily Accessible Interface
% Improvement
Good
Recovery Track(er)
Fair
Poor
20
Summary



Device to enable clinicians to track recovery of
post ankle surgery patients using in situ
quantifiable data
Comfortable and lightweight in order to ensure
accessibility and encourage frequent use and
‘normal’ data output
Consists of a patient take-home piece:
(1)force sensing insole, (2) data acquisition box,
and an in-office analysis piece:
(3) easy to use data analysis and display software
Recovery Track(er)
21
Acknowledgements
Our group would like to thank:
Professor Hillman
Professor Sajda
Professor Kymissis
Recovery Track(er)
22