Recovery Track(er)
Design Summary
1.
Design Problem and Brief
1.1 Design Problem
The ankle bears the most weight per unit area then any other place in the body. During
exercise it can be subjected to as much as one million pounds of pressure. Ankle injury,
specifically ankle sprains are the most prevalent injury during recreational activity.
Injuries are treated either by temporary immobilization via a cast or brace or, in more
severe cases, by surgical repair and reconstruction. 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 the clinic on a regular basis and perform a series of weight baring and gait
analysis test. These tests only estimate normal function and do not provide an in situ
measure. They do not take into account different usage levels, intervals, or surfaces.
Furthermore, traveling to the clinical on a regular enough basis is inconvenient for the
patient. Depending on patient reliability this tests may be hampered by non regular time
intervals between testing.
1.2 Design Brief
We propose to build a device which will help patients track their rehabilitation process
after foot or ankle surgery . 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 collected
information will be relayed back to a central computer where the collected data will be
compared to normal values. The original force data as well as the quantitative
comparison will be displayed in an easily accessible interface. This device will allow
clinicians and physical therapists to better track a patients process post – surgery.
2.
Research
2.1 Summary of Ankle Injury, Surgery, and Recovery
2.1.1 Ankle Injury
2.1.1.1 Ligaments
Seventy five percent of all ankle injury are due to tear or strain on ligaments [7]. These
injuries also represent the majority of all injuries incurred during recreational activity,
from 0.65 to 3.85 injuries per 1000 person-days of activity [5]. Eighty five percent of
ankle strains result from injury of the lateral injury on the outside of the ankle. The inner
ankle is more stable the outer ankle, thus, the ankle has the ability roll inward or invert
straining the outside lateral ligament [4]. Several factors contribute to the occurrence of
LAS including, hard impacts either with the ground while falling or with another athlete, ill
fitting shoes, or inconsistency in the ground surface. Intrinsic factors such as low Achilles
tendon flexibility or weakness of he peroneal muscles may also contribute [3]. Treatment
of lateral ankle sprain (LAS) depends on the severity of the injury and usually follows
one of three modalities: functional treatment via an ankle brace, immobilization via a
cast, or surgical reconstruction. There has been little statistically significant evidence
supporting one treatment option over another [6]. However, the end result and time
Recovery Track(er)
frame of recovery is different for each patient even within the same treatment area.
Furthermore, it has been estimated that ankle sprains cost $300 to $900 per person
with an aggregate cost of $2 billion annually in the United States alone [8].
2.1.1.2 Tendons
Tendon injury in the foot and ankle is usually attributed to strain on the Achilles tendon.
The Achilles tendon connects the heal muscle to the muscles along the back of the calf.
With every step the Achilles tendon is subject to at least the entire body weight. More
weight may be felt depending on weather the person is running, jumping, or carrying
weight. Because of its key position in motility the tendon is highly used and subject to
frequent injury. A sudden onset of activity or periodic activity with long periods of rest,
put a person at risk for injuring the tendon. Those with over ponation or flat feet are also
at risk due to the greater demand placed on the tendon while walking. Injury can be
prevented by proper fitting shoes, orthopedic insoles, and/or proper conditioning and
training. The Achilles tendon can be subjected to varying degrees of injury. Inflammation
of the tendon, or tendonitis due to overuse or misuse is treated by rest, icing, and proper
stretching. Persistent injuries may be further treated with physical therapy involving
strengthening exercises, muscle massage, and re-education. At the high end of the
spectrum is tendon rupture. Overstretching the tendon can cause partial or full rupture.
The causes of tendon rupture are similar to those leading to tendonitis: flat feet, running
on hills, tight calf muscles, poor training habits, or overuse. The treatment for rupture
almost always involves surgically stitching the ends of the ruptured tendon back
together. Although non-surgical methods exist (i.e. wearing a brace or surgical shoe)
they are not as effective, require longer recovery time, and carry a greater probability of
re-rupture. Recovery from the surgery still requires six to eight weeks in a walking cast
or brace, and four to six months of rehabilitation therapy[1].
2.1.1.3 Bone
Ankle fractures occurred with an overall age- and sex-adjusted incidence rate of 187 per
100,000 person-years; this is higher than in earlier population-based studies. [9] The
ankle joint is made up of three bones coming together, the tibia, fibula, and the talus. A
fracture in any of these bones is often accompanied by a simultaneous tear in the
ligaments, and can be caused by the rolling or twisting of the ankle, extreme flexing of
extending of the joint, or severe force applied to the joint by coming straight down on it
as in jumping from a high level. Treatment for an ankle fracture depends on the severity
of the injury. Very minor fractures can be treated like an ankle sprain, but serious
fractures often require the placement of a splint on the injured ankle. If pieces of bone
have broken off, then it is a called a compound fracture and requires surgery to set the
bones before a splint can be placed. [10] The average fracture takes about four to eight
weeks to heal, although follow-ups are usually recommended during that period. [11]
The average cost of treatment is the United States is estimated at $2,143 per person.
[12]
2.1.1.4 Joint- Osteoarthritis
Osteoarthritis of the ankle is characterized by the breakdown and eventual loss of
cartilage in the ankle joint. Although ankle osteoarthritis accounts for only 4.4% of all
osteoarthritis cases [13], a recent study found that out of 639 people with osteoarthritis
of the ankle, 445 (70%) of those patients had previously experienced ankle trauma,
making it crucial to properly observe and treat ankle injuries of any kind. [14] The causes
of osteoarthritis are not fully known, but the rudimentary reason is the daily wear and
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Recovery Track(er)
tear the joint receives. This causes the cartilage between the bones to weaken and thin,
causing the bones to rub together, which results in pain and inflammation. [15] There are
many treatments for osteoarthritis, and options include both surgical and non-surgical
treatments. Oral medications and steroid injections can be given to help pain and
swelling. The same outcome can be achieved using orthotic devices which cushion the
foot and help right bad ankle movement, and can be used in conjunction with physical
therapy. Surgical options depend on the severity of the condition, but can include the resetting of bones to help alleviate symptoms with non-surgical methods prove ineffective.
[15] Recovery time is not applicable to arthritis as it is a degenerative condition, meaning
it worsens over time. Treatment costs can run anywhere from $15 for an ankle brace
which can be purchased from a sporting goods store, to much higher for prescription
medications, to around $66,000 for surgery. [16]
2.1.2 Recovery From Surgery
2.1.2.1 Current Methods
Sample Physical Therapy protocol in recovering from Achilles Tendon repair surgery:[17]
Phase I (0-8 Weeks):
Therapeutic Exercise:
0-2 Weeks: NO physical therapy or motion
2-8 Weeks: Inversion ROM, stationary bike with brace on, knee/hip strengthening, joint
mobilizations
Brace:
0-2 Weeks: Worn at ALL times
2-4 Weeks: Brace worn at all times except for exercise and hygiene
4-8 Weeks: Worn during weight bearing activities
Weight Bearing:
0-4 Weeks: heel-toe touchdown weight bearing in post-op splint
4-8 Weeks: As tolerated with crutches
Phase II (8-12 Weeks):
Therapeutic Exercises: Begin light resistive exercises, continue with bicycle and
knee/hip strengthening
Brace: None
Weight Bearing: As tolerated with crutched- discontinue crutch use when gait is
normalized
Phase III( 12 Weeks- 5 Months):
Therapeutic Exercises: Progress Phase II activities, becoming more aggressive
Brace: None
Weight Bearing: Progresses to full with a normalized gait pattern
For our purposes this means that for typical ankle surgery, there is a period from 12
weeks- 5 months where the patient is mostly recovered, but is still in need of some
physical therapy. During this time, their range of motion is supposed to progress to a
normalized gait pattern, which Recovery Track(er) can help them monitor. This allows
them to monitor their progress and continue to strengthen their ankle without frequent
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Recovery Track(er)
visits to the physical therapists for such an extended period of time, which becomes both
expensive and inconvenient.
2.1.2.2 Recovery Time
The recovery time for ankle injuries vary greatly depending on the type and severity of
the problem. For simple sprains, recovery time tends to be minimal, ranging from one to
two weeks. Severe sprains that involve overstretching of the tendon will be considerably
longer, in the range of four to six weeks, while recovery time for tendon injuries that
require surgery will be in the order of six to eight weeks. Damage to the bones that make
up the ankle can also have significant recovery time, ranging from four to eight weeks
depending on severity. For arthritic ankle problems there is no recovery time, as they are
degenerative diseases. However, in all cases, care must be taken to not put too much
pressure on the injured joint so as to prevent further and future injury.
2.1.3 Problems with current methods
2.1.3.1 Patient Compliance
Patient compliance of ankle injury treatment is of the utmost importance when
attempting to prevent a reoccurrence of injury. For severe injuries such as tears and
fractures, which require extensive medical care, compliance tends to be higher than that
of standard lateral ankle sprains. It was also found that patients often thought that
compliance with a recovery regiment will not significantly contribute to their recovery or
that the problem will resolve itself without adhering to the regiment. [19] The young and
athletic also tend to be less compliant than the older non-athletic population making the
occurrence of re-injury higher in that population. Another problem regarding compliance
is patients’ dislike of in office visits. A study comparing patients who had in office therapy
visits, who tended to miss visits as the therapy continued, to those who received at
home therapy showed a significant improvement in pain, mobility, and function. [20]
2.1.3.2 Recurrence of Injury
Reoccurrence of injury is very high in ankle injury patients. It was found that residual
symptoms after lateral ankle sprains effect 55% to 72% of patients at 6 weeks to 18
months. [18] Another study found that 9% of patients completely re-sprain their ankle
due to poor follow up. [21] It is likely this is due to patients returning to normal activity too
quickly and without proper rehabilitation of the injury. [18] Proper knowledge of one’s
recovery progress will greatly reduce the incidence of re-injury. One study of sports
injuries showed that strict monitoring of recovery greatly reduced reoccurrence of injury,
and again it was concluded that this was due to proper tracking of injury allowing proper
recovery time. [22]
2.1.4 Who is the user?
We expect the primary user to be the patient themselves. Ideally the patient would use
the device outside of the clinical environment, and outside of therapist or physician
supervision. Thus, the product must be able to withstand and interface with a diverse
array of users. Furthermore, in order to encourage a level of use which will be most
useful to the attending physician or physical therapist, the hardware of the device must
provide be comfortable for the patient to use, and the software must be comfortable for
the patient to interact with. The data acquired from patient use can then be used either
by the attending clinician or physical therapist to track individual patient progress, or by
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Recovery Track(er)
an investigator to compare recovery from different surgical or other treatment
techniques.
2.1.5 Who is the customer?
The customer will be physical therapist offices or hospitals. This device will supply
physical therapists with quantitative data on the progress of their patient. As a result they
will be better equipped to monitor the results of both outcome and recovery. Hospitals
can use this device to collect data on the effectiveness of certain treatments by testing
subjects before and after. This information can guide their decisions on which treatment
options to recommend to patients in the future.
If the patient was expected to use the device in their home as part of treatment it is
possible that the prescribing hospital or physical therapist may request payment to cover
the capital cost of the device as well as maintenance and data analysis costs. Most
likely, these expenses would be forwarded on to the patient’s insurance company. Thus,
the device will need to be reimbursable by insurance companies. It needs to
demonstrate both efficacy and safety, endorsed by clinicians, and FDA approved. The
prior existence of similar products [2] will ease the approval and reimbursement
clearance process.
1.
Achilles Tendon Rupture, in Fitness, MayoClinic.
2.
F-Scan, in Medical Mappind Devices, TekScan.
3.
Inversion Ankle Sprains, in Articles and Resources, American Academy of
Podiatric Sports Medicine.
4.
Treatment and Rehabilitation, in Foot and Ankle, American Academy of
Orthopaedic Surgeons.
5.
Beynnon, B.D., et al., Ankle ligament injury risk factors: a prospective study of
college athletes. J Orthop Res, 2001. 19(2): p. 213-20.
6.
Kerkhoffs, G.M., et al., Surgical versus conservative treatment for acute injuries
of the lateral ligament complex of the ankle in adults. Cochrane Database Syst Rev,
2007(2): p. CD000380.
7.
Morrison, K.E. and T.W. Kaminski, Foot characteristics in association with
inversion ankle injury. J Athl Train, 2007. 42(1): p. 135-42.
8.
Soboroff, S.H., E.M. Pappius, and A.L. Komaroff, Benefits, risks, and costs of
alternative approaches to the evaluation and treatment of severe ankle sprain. Clin
Orthop Relat Res, 1984(183): p. 160-8.
9.
Bengner, U.;Johnell, O.; Redlund-Johnell, I. Epidemiology of ankle fracture 1950
and 1980. Increasing incidence in elderly women. Acta Orthop Scand 57(1):35-7. 1986.
10.
Ankle Fracture. 8 Oct. 2005. eMedicineHealth Emergency Care and Consumer
Health. 4 Nov. 2008.
<http://www.emedicinehealth.com/ankle_fracture/article_em.htm#Ankle%20Fracture%20
Overview>
11.
Bewes PC. The management of ankle fractures. Trop Doct. 1995;25:58–62
12.
Bhandari M, Sprague S, Ayeni OR, Hanson BP, Moro JK. A prospective cost
analysis following operative treatment of unstable ankle fractures: 30 patients followed
for 1 year. Acta Orthopaedica Scandinavica. 2004; 75:100–105.
13.
Cushnaghan J, Dieppe P. Study of 500 patients with limb joint osteoarthritis. I.
Analysis by age, sex, and distribution of symptomatic joint sites. Ann Rheum Dis. 1991
Jan;50(1):8–13.
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Recovery Track(er)
14.
Saltzman C, Salamon M. Epidemiology of Ankle Arthritis: Report of a
Consecutive Series of 639 Patients from a Tertiary Orthopaedic Center. The Iowa
Orthopaedic Journal.
15.
Demetriades L, Strauss E, Gallina J. Osteoarthritis of the Ankle Joint. Clin
Orthop. 1998;349:28–42.
16.
Ankle Fusion: Surgical treatment of Ankle Arthritis. 19 Oct. 2005. University of
Iowa Hospitals and Clinics. 4 Nov. 2007.
<http://www.uihealthcare.com/depts/anklearthritis/patientinfo/fusion.html>
17.
http://www.peninsulaortho.com/downloads/achilles.pdf
18.
http://www.hsedu.com/ThemeFiles/Ankle/LateralAnkleSprain.pdf
19.
http://www.ptjournal.org/cgi/reprint/73/11/771
20.
http://www.annals.org/cgi/reprint/132/3/173.pdf
21.
Epidemiology of Sprains of the Lateral Ankle Ligament Complex. Foot and Ankle
Clinics of North America, Volume 11, Issue 3, Pages 659-662 N. FERRAN
22.
http://ajs.sagepub.com/cgi/content/full/35/9/1433#T2
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Recovery Track(er)
2.2 Products that Meet the Same Need
http://www.sensorprod.com/podiascan.php
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Recovery Track(er)
F-Scan® VersaTek System
bipedal in-shoe analysis
System Features
F-Scan®
is a measurement system that captures dynamic in-shoe
pressure information revealing interaction between foot and
footwear. Unlike traditional visual observation of foot function
and gait, F-Scan quantifies contact pressure distribution and
timing. It includes sensors, electronics, and software as well as a
protocol for analysis, diagnosis, and confirmation of the
effectiveness of interventions. The extremely thin, high resolution
F-Scan sensor ensures the most accurate data is captured. Other
proponents of the system include:
USB Connection to laptops makes the system easy-to-use and portable.
Faster scan rates enable better capture of dynamic events & plantar pressure
assessment.
VersaTek® cuffs feature light weight hardware, indicator lights, and standard CAT5E
cables.
New Edge connection provides more reliable connection to sensor.
For clinicians dissatisfied with the limitations of traditional examinations, F-Scan confirms
the efficacy of treatment. For researchers investigating or studying foot function, gait, and
footwear design/function, F-Scan provides biomechanical parameters and understanding
of how the foot and gait are functioning.
1. Trim
2. Connect
3. Collect
Ultra-thin, highresolution sensor 960 sensels
Edge Connect sensor;
USB connection to
850 Hz Scan Rate
PC
4. Analyze
Analyze pressure
data for high risk
areas
Applications:
Benefits:
Screen for disorders secondary to diabetes or
other neuropathic issues
Observe gait abnormalities
Regulate weight bearing after surgery
Monitor degenerative foot disorders
Assess high pressures due to ray hypomobility
Immediate determination of orthotic efficiency
(View Case Study)
Pre- and post-surgical evaluations
Manage treatment of foot inside the
shoe
Increase orthotic footwear performance
Reduce cost by reducing the need for
follow-up and orthotic adjustments
More referrals by increasing patient
satisfaction
Supporting documentation for fee-forservice approach or insurance claims
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Recovery Track(er)
Identify areas of potential ulceration
Segment various regions of the foot
http://www.tekscan.com/medical/system-fscan1.html
MatScan® System
barefoot analysis
System Features
MatScan®,
a low-profile floor mat, captures barefoot plantar
pressures and forces for objective, quantified data to support
diagnosis and mode of treatment. Unlike traditional tests, MatScan
provides insight into foot function and biomechanics, and
identifies regions of high plantar pressure that cannot be seen
with the naked eye. MatScan is available with either Evolution® or
VersaTek® electronics.
Screen patients on the basis of foot pressures, function and postural related problems.
Quickly identify foot pressures, foot function and some gait parameters.
Monitor the progress / efficiency of foot function during rehabilitation or muscle training.
Recommend orthotic or footwear in a retail setting.
1. Connect
2. Collect
3. Analyze
USB Connection to PC
500 Hz Scan Rate with
VersaTek electronics
Analyze pressure data
for high risk areas
Applications:
Benefits:
Identify plantar pressure profile discrepancies
between left and right feet
Identify asymmetries during stance phase
Perform in-depth analysis of foot function by
isolating the heel, midfoot, and forefoot during
stance phase
Review dynamic weight transfer and local
pressure concentrations
Identify areas of potential ulcerations
Monitor improvements in balance, sway,
strength & weight bearing
Expand your client population through
proactive foot screenings
Reduce incidence of ulcers and speed
healing time
Sense what the neuropathic foot cannot
feel
Supporting documentation for fee-forservice approach or insurance claims
Educational tool to teach rehabilitation
exercises for the lower limb
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Recovery Track(er)
Segment regions of the foot
http://www.tekscan.com/medical/system-matscan1.html
2.2.1 Summary
Podia-scan is used for foot pressure mapping systems, but only for stationary pressure
mapping. It cannot track pressure changed as the foot moves depending on gait.
TekScan has two different designs devices available for measuring the applied pressure
of a foot: it could be “in shoe pressure sensor” or simply a “mat sensing pressure”. They
are based on both analyzing the applied force or load and transmitting to a computer an
image showing where the pressure is applied. The mat sensor seems to be easier to
perform but both achieve the same results. We did not see, however, any commercial
devices that are completely wireless and able to be used by our customer for a long
period of time in order to acquire a great amount of data on a day by day basis.
2.3 Products that Have the Same Function
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Recovery Track(er)
http://www.sensorprod.com/pdf/pressurex-mirco_brochure.pdf
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Recovery Track(er)
http://www.sensorexpert.com/brochure/sensor-film_brochure.pdf
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Recovery Track(er)
1.973.884.1755
1.973.884.1699
1.800.755.2201
phone
fax
toll free (U.S.
Only)
info@sensorprod.com
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$8,245.00
Consumers want confidence that the choice of mattress they make will
guarantee them a good night's sleep for years to come.
FSA Retail Bed Pressure Mapping Systems give sales staff visual and
easily understood 'proof' that they can use to guide the customer to the
best sleep solution.
The customer is clearly shown which mattress promises optimal
comfort. The easily understood picture of pressure distribution leaves
the customer feeling better informed and more confident about their
decision.
FSA Bed Pressure Mapping Systems have been used in hospitals to select mattresses for nearly two
decades, in order to prevent pressure sores.
The pressure picture allows customers to quickly understand why they are uncomfortable at night.
The easily understood pressure information helps the customer select a bed solution with confidence
that their choice will ensure comfort and a good night's rest.
FSA Retail Bed installations have proven their value several ways:
by
Increasing lease line crossing
Increasing the in-store time with consumer
Increasing conversions
Increasing per unit sale price
Increasing the number of happy, confident customers
FSA is a flexible system. Options include:
Retail Software:
Customized to your appearance and function requirements
Simple One-Button Operation
Displaying your own brands and models
Standard FSA software:
Sophisticated, full clinical functionality used by medical facilities
Other options include:
Different sizes and types of sensing mats
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Recovery Track(er)
Wireless,
Touch Screen Tablet PC Control,
Multiple sensor set-ups,
Data gathering,
and other specified requests
Please click here to open a video of the Retail Bed System
FSA Mat Name
Bed
Serial Number Prefix
Sensing area length
(mm)
Sensing area width
(mm)
3030
1920
762
Poly Thickness (mm) 4
Screenshot
Sensor Dimensions
(line widths)
Email Item
20.5 x 57
mm
(13/16" x 2
1/4")
Add to Cart
Space between
sensors - Height
3.1
(mm)
Space between
3.4
sensors - Width (mm)
Sensor Arrangement
32 x 32
Standard Calibration
Range (mmHg)
100
Finished Mat Length
(mm)
Finished Mat Width
(mm)
2032.0
(79.25")
873.4
(34.4")
Iso Bag Size
Required
36" x 84"
Sensing Area (mm2)
Sensor Number
1463040
1024
Sensor Surface Area (mm2)
1001
http://www.pressuremapping.com/index.cfm?pageID=13&section=16
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Recovery Track(er)
2.3.1 Summary
As we can see, pressure sensors can be utilized in many other areas, both within
medical diagnosis and outside. The first product listed- the Pressure Mapping System is
used to produce a full color pressure analysis displayed using a user friendly software,
much like what we are aiming for in Recovery Track(er). However, it is used for a very
different end-use of mechanical processes such as heat sealing and door seal closure
analysis. Another product with the same function is the Tactile Pressure Sensing Film. It
is used to instantly evaluate pressure between two touching surfaces in the aerospace,
automotive, electronics, and many other industries. It is a disposable, one-time use
pressure film, and we could look into similar products to use in our product. The final
product, the FSA Bed Pressure Mapping System is a prime example of pressure
mapping in the medical diagnosis industry. It collects pressure data to help allow
customers to understand why they are uncomfortable at night.
2.4 Interviews
2.4.1 Staff, JackRabbit Sports, 42 West 14th Street New York NY,
www.jackrbt.com
JackRabbit Sports is a triathalon supply store which stocks shoes and apperal for
serious runners, and offers free shoe footing service. We thought the staff at JackRabbit
may be able to tell us more about their shoe fitting system, other systems in use, and the
features they try to detect using their system.
Amy at JackRabbit was very helpful. She said that all the staff go through an extensive
training to be able to fit shoes to customers. She was also an avid runner and interested
in the project from a personal point of view.
The shoe fit system consists of two video cameras and a treadmill. Customers are asked
to try on a “neutral shoe” and walk or run at their own speed on the treadmill while video
is shot of their feet. The staff then watch the video full length or frame by frame. The
system is solely used to detect ankle ponation and is not equipped to give force
distribution information. Based on the degree of ankle ponation, customers are
recommended different styles of shoe. Those who over ponate are offered a shoe with
more ankle support, while those who under ponate and directed towards a neutral or
less ankle restrictive shoe. The system can also be used to do basic gait analysis.
The JackRabbit system detects and attempts to support preexisting running or walking
conditions. It is not a value based system and is limited in its data.
According to Amy the cause of ‘shin splints’ is the wearing of shoes un-supportive to
ones personal ponation. This suggests we may want to talk ponation into account in
design and data acquisition of the insole.
2.4.2 John Kymissis, Assistant Professor, Columbia University
Prof. Kymissis is currently running a research program investigating piezoelectric film
sheets. We discussed one in particular made of Polyvinylidene diflouride (PVDF). When
the thickness of a PVDF sheet is changed the electric field is altered and current is
produced. The response to stimuli is almost perfectly linear which makes it very
attractive for our application. However, the current created by the PVDF when directly
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Recovery Track(er)
compressed is not enough to measure with any degree of certainty. Professor Kymisssis
suggested that the only way to get enough signal out of the PVDF is to subject it to
bending stress. Thus, to be useful in our application the PVDF would need to be bent
over a ridge or bump. Applying pressure would cause the PVDF to unflex. Pressure
information could then be read through calibration of the flexing and unflexing of the
PVDF. Advantages of PVDF include its linearity, and area independence: the outputted
voltage does not depend on the area of the sample, thus, the PVDF could be shaped as
needed to fit our design without biasing the data.
Prof. Kymissis also suggested looking into elastomer or rubber polymers which have
been shown to give spatially relevant pressure data from one continuous sheet
(Someya, Takao, “A large-area, flexible pressure sensor matrix…’”, PNAS Jul 2004
101.27). This technology seems interesting but may be too complicated and expensive
for our application.
Another good suggestion by Prof. Kymissis was to recruit an Electrical Engineering
student to combine their senior design project with ours. Taking on a EE student would
allow us to explore more complicated signal collection without challenging the integrity of
the rest of our project.
2.5 Summary of Safety Requirements
2.5.1 Safety Concerns
The safety concerns regarding our device are threefold:
2.5.1.1 Electrocution
When dealing with any electrical device, there is always a risk of electrocution. Proper
surge protection and other safety measures would have to be taken to ensure the safety
of the user.
2.5.1.2 Injury
Since the user will be running while the device is operating, comfort and stability are
important. If the device does not fit the user’s foot properly, there is a likelihood that a
running related injury (rolled ankle, tripping) could occur.
2.5.1.3 False Data
When dealing with medical diagnosis, the data and interpretation needs to be totally
accurate. If the final design of the product is to provide a diagnosis, then the
interpretation of the data needs to be correct. The data needs to be accurate whether or
not this is the case.
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Recovery Track(er)
2.5.2 FDA Regulations
3.
Design Specifications and Constraints
3.1 Basic Mechanism
The device reads the movement of the foot, and transmits this data to a computer. The
software that works with the device then analyzes the data and outputs the data in a
accessible interface. This interface can be designed to give a range of outputs from full
data graphics and visualization to a progress report tailored to user needs.
3.2 Social Impact
This device will allow greater access to gait diagnostics. With access to quantitative data
on recovery progress, clinicians and physical therapists (PT) will be better able to help
their patients stay on track. Additionally, they will be able to evaluate their own patient
recovery techniques using unbiased quantitative methods.
3.3 Accessibility and Training
Accessibility is a large constraint on our design. The success of our product depends
largely on its ease of use, both on the patient and PT side. Patients must find the data
collection component of the device easy and comfortable to use. The benefits of
analyzation require accurate and great quantities of data. Patients will be more inclined
to use the device if it does not interfere with their daily activities or require much training
to use. Likewise, physical therapists are not going to want to spend a large amount of
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Recovery Track(er)
time learning how to use a product for one specific group of individuals. Thus, the device
must be as intuitive as possible.
3.4 Reliability
Reliability of the device is, of course, important. However, it is as important to remember
that it does not support patient life, and therefore, failure of the device is not life
threatening. Yet, to provide proper tracking information the device needs to collect
pressure information the same way each time it samples, both from individual patients,
and from groups of patients.
3.5 Ergonomics
Ergonomics are a very important part of our design. The in-sole has to fit a spectrum of
foot sizes, and must conform well to the shoe and foot and be comfortable. Since the
device is designed for patients recovering from surgery, it is vital that the device not
cause further damage to the individual, as well as take into account possible limited
range of motion and pressure tolerance.
3.6 Power
As a portable device it will be powered via battery. The most useful design will have
rechargeable batteries that add little weight or bulk to the device. Lifetime of the battery
is not as important as size as users will be at home with access to power.
3.7 Cost
3.7.1 Manufacturing Cost
Manufacturing Cost: Control Box: $50. Analysis Software: none after development costs.
Insole: $100 Total: $150
3.7.2 Purchasing Cost
The cost of the initial hardware (microprocessor, memory, and output) and analysis
software will be kept under $200. The cost of each sensor insole less then $150. If any
disposable parts are needed their cost should be kept at a minimum (<$25) to
encourage frequent use.
3.8 Distribution
The device will be distributed by us directly to hospitals or physical therapist offices.
Once the initial device is purchased revenue can be generated by offering existing
customers upgrades to the device software. Expanding mainly through software keeps
our manufacturing costs low and allows us to maintain anonymity from a larger
distribution source. It also allows us to focus on customer service aspects of our
company which will distinguish us from our competitors.
3.9 Lifetime of the Product
3.9.1 For the User
For the user, the life of the product will be however long the materials and electronics
last. The product will be designed to withstand the forces incurred from the user walking
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Recovery Track(er)
and running on it, however, some wear will occur. Depending on the user failure may
occur in the insole itself. We can only guarantee the insole for a year of use, if we
assume all use is heavy. New models and upgrades will be offered, and the cost of new
insoles will be kept low.
3.9.2 For the Company
The life of the product depends on the rate of technological advancement. There is likely
to be a better product (created by either ourselves or a competing company) within five
to ten years. We can also expand our product through software upgrades.
3.9.3 Warranty
There will be a warranty and training program to go along with this device. This device
will not be self-serviceable, and will require a technician for repairs or upgrades.
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