Assessing amputee gait patterns can be a remarkably complex and
challenging task for prosthetists. Lack of access to gait laboratories combined
with time constraints and added costs represent major barriers to formal gait
analysis for most practitioners. Instead, prosthetists traditionally have
relied on observational analysis learned and refined over years of clinical
practice to assess gait patterns. However, with all of the technological
advances that have occurred in recent years, various tools have become
available that can aid practitioners in making some basic gait measures.
Observational analysis
Because most practitioners do not have access to instrumented gait
analysis, they rely primarily on observational gait analysis to assess amputee
gait in the clinic setting. Practitioners make specific prosthetic
recommendations, changes and design features based primarily on visual
observation of patients walking on their check socket. Many gait deviations can
be observed in the frontal plane even if they do not occur in that plane,
John T. Brinkmann, MA, CPO/L, FAAOP, an instructor at Northwestern
University Prosthetics-Orthotics Center and Gait Society chair for the American
Academy of Orthotists and Prosthetists, said.
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| John T. Brinkmann |
“The most common thing is to observe gait in the frontal plane, so
you are having the patient walk away from you and toward you. Ideally it is
good to also get a view from the sagittal plane,” Brinkmann told
O&P Business News. “The reality of most office situations is
you do not have a great way of doing that. Patients can walk down a hallway
away from you for 20 feet, but to get a true sagittal view you either have to
watch patients as they walk by the door of the exam room, or you have to follow
alongside them. It is helpful to have a big enough room that you can stand in
one place while they walk.”
One of the most basic and easily accessible tools practitioners can use
in the clinical setting to aid in assessing gait is a camera with the
capability of slow motion. Although the ideal setup is to use a camera and
tripod so that the camera remains steady and the right plane can be captured,
Brinkmann noted that even a smart phone can be used to capture video.
“The single greatest thing anyone can do for orthotic or prosthetic
gait assessment is to capture video,” Brinkmann said. “Being able to
watch the same gait cycles multiple times and then slow down the video,
especially in more complicated cases, is invaluable. Even for an experienced
person assessing gait visually, there are so many things going on in such a
short amount of time that it is hard to catch the nuances.”
Video allows practitioners to evaluate separate segments of gait and
their relationships to each other. The video also allows practitioners to
rewatch a patient’s gait cycle without having the patient walk multiple
times. Moreover, the initial video can be used as a baseline to compare with
future videos obtained after additional interventions and adjustments to assess
the effects of therapy and determine if there has been any improvement.
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| Steven A. Gard |
Brinkmann noted less expensive camera systems also are becoming
available. Although such systems are not as sophisticated as those available at
full gait labs, some cameras allow for a view of approximately 180·.
This enables the camera to be used in a narrow area to obtain frontal and
sagitttal views of a patient walking down a hall.
“If you want to get a true sagittal side view, the camera has to be
able to follow the person because as soon as you record at an angle, it changes
the perceived joint angles, or it appears to,” Brinkmann said.
Gait mats and activity monitors
Another gait assessment tool that clinicians can use fairly easily in
the clinical setting is a gait mat. Gait mats, which can be set up in a fairly
limited amount of space such as a hallway, are designed to collect basic
information as patients walk on the mat.
“One of the advantages of something like the GAITRite is that there
is no subject preparation required. You simply roll out a mat and have people
walk back and forth a few times,” said Steven A. Gard, PhD,
executive director of Northwestern University Prosthetics-Orthotics Center,
director of Jesse Brown VAMC Motion Analysis Research Laboratory, and a
research associate professor in the department of physical medicine and
rehabilitation at Feinberg School of Medicine.
Some of the fundamental gait parameters that are collected by gait mats
include step length, cadence and walking speed. Practitioners can then use such
measurements for documenting and tracking patient progress over time.
“Walking speed itself is one of the first gait parameters that I
look at when I am doing an evaluation of pathological gait because generally
people will adopt a freely selected speed of walking at which it is thought
that they minimize energy expenditure,” Gard told O&P Business
News. “Walking speed has been shown to be proportional to energy
expenditure during gait, so a person with greater impairment will tend to walk
slower. If you have an intervention that improves the way that somebody walks,
then presumably you are increasing function and making that gait more
efficient.”
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| Image: Courtesy of Steven A. Gard, PhD |
To obtain walking measurements collected over a longer period of time,
practitioners can use Orthocare Innovations’ StepWatch Step Activity
Monitor. Basically an accelerometer, the StepWatch is a
microprocessor-controlled device that can be strapped onto a patient’s
prosthesis to record the patient’s walking activity for up to period of 2
months. At the end of the monitoring session, the collected data collected are
downloaded and analyzed by accompanying software.
The StepWatch Step Activity Monitor can provide a good snapshot of how
patients are using their prosthesis in the real world, Gard said. In addition,
he noted that the monitor has been used to compare patients’ activity
levels wearing different types of prosthetic components.
Compas and Smart Pyramid
Compas (Computerized Prosthesis Alignment System) and Smart Pyramid from
Orthocare Innovations is a technologically advanced assessment tool designed
specifically for prosthetic use in a clinical setting. The system, first
realeased in 2009, is designed to aid prosthetists in aligning prostheses.
“The Compas and Smart Pyramid is the first accessible gait
assessment tool for prosthetics that bridges the gap between observational gait
and a full-fledged gait lab,” Brinkmann said. “It is an extremely
exciting development because it now takes a completely subjective process and
puts some kind of actual numbers to it, which we have never had for prosthetics
unless you put somebody in a gait lab.”
The system consists of two parts. The Smart Pyramid is basically a
pyramid with a four-hole pattern that is mounted to the socket and contains the
actual sensors. The Compas Master unit is attached to the Smart Pyramid for
active data collection during a patient’s office visit and then the data
is sent via Bluetooth to a computer to be analyzed. After the data collection
has been completed, the Compas Master unit is removed.
“The device has a set of eight strain gauges built into it to
measure the strain across this pyramid, and when all of that data gets dumped
into the software, what you get is two moment profiles,” Jason Wening,
MS, CPO, FAAOP, clinical research director at Scheck & Siress, said.
“It is a moment profile at the Smart Pyramid, wherever that happens to be
in the prosthesis, and it is in the sagittal and coronal plane, so front to
back and side to side if you have the pyramid aligned and calibrated
correctly.”
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| The IPecs Pro System will provide objective data to help prosthetists align and fit prosthetic devices. |
| Image: College Park Industries |
Wening noted that the system is not set up to address all six degrees of
freedom that prothetists normally consider for alignment. The system does not
have the ability to assess whether the height of the prosthesis is correct or
whether the transverse rotation is correct.
“You can take the data and with a good clinical understanding of
the type of patient that you are dealing with, the gait habits that patients
present with when they walk in the door, the type of foot that they are using
on the prosthesis, the type of knee that they are using, the design and how
well the socket fits, you can use the data that this system gives you to try to
improve the alignment of the prosthesis,” Wening told O&P Business
News. “The logical leap would be if you have improved the alignment of
the prosthesis, you have improved the gait pattern of the amputee walker. That
is the end goal.”
In fact, the system can allow practitioners to identify alignment
problems that they are unable to discern visually. “It makes us better
because we think we are seeing certain things, but we cannot actually tell what
is going on with a lot of the forces inside the socket and in the prosthesis.
You just see these gross motions, such as a lean or a rotation problem,”
Brinkmann said. “What they are finding is that you can align the
prosthesis to where an experienced prosthetist thinks ‘This is perfect
alignment.’ You can then put patients on this system and you will realize
that significant changes would improve their gait.”
Because the system is designed for clinical use, the cost of the device
is billed either to patients directly or to their insurance company as an
inline alignment measurement tool that is part of the prosthesis. Wening noted
that some insurance companies are paying for the device.
iPecs
Another tool on the market for amputee gait assessment is the iPecs Lab
system from College Park Industries. The system, which has been available for
approximately 2 years, was designed specifically as a research tool for gait
analysis. Development of the system was partially funded by the Eunice Kennedy
Shriver National Institute of Child Health and Human Development. College Park
also worked closely with Northwestern University, and last fall the system was
awarded first place in the Electronic product category in the NASA Tech Briefs
Create the Future Design Contest, Mike Leydet, director of research at
College Park Industries, said.
The iPecs Lab has the ability to measure six degrees of freedom
comprising three-axis forces and moments including transverse rotation in a
portable device that can be used in a variety of real-world environments.
“You can collect a lot of this data with different means inside a
gait lab, but if you want to go outside of the gait lab, this is the device for
amputee gait analysis,” Leydet told O&P Business News.
“Literally, you could walk for 2 hours up a mountainside and collect every
one of those steps, bring it back, and start to analyze and characterize some
of the types of loading conditions that you would see in that
environment.”
Although the iPecs Lab is geared specifically toward researchers,
College Park just recently received a patent for a clinical version, which will
be called the iPecs Pro. Leydet estimated the iPecs Pro would be available for
practitioners to use in the clinical setting within the next 6 to 8 months.
“The challenge there is really trying to take and provide a very
utilitarian approach to assist in the alignment process and then provide
documentation features for the prosthetists so that they can help support their
reimbursement claim,” Leydet said. “We all know how that is a hot
topic, and that is the way the world is going, outcomes based, having objective
measures to support what we do on a daily basis, whether you are an engineer,
physician or a prosthetist.”
Leydet noted that the iPecs Pro is being designed to assist prosthetists
in the alignment and fitting of prosthetic devices and also to provide
objective rather than subjective data. In addition, he noted that while the
cost of the iPecs Pro has not been determined as yet, they are working to make
it as affordable as possible for clinicians.
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| Gait analysis markers must remain stable for accurate measurement. | |
| Image: Steven A, Gard, PhD | |
“The reality is it is much tougher to make that product for the
clinician because it has to bridge the gap between the research talk and the
engineering talk, and what is practical for making reasonable adjustments to
the prosthetic fitting,” Leydet said. “Essentially, we’re
merging cell phone technology with some high-end computer software applications
along with an industrial load cell system, and there are a lot of hoops to jump
through to be able get all of those things to work together in unison and then
provide something that is meaningful for the end user. It is definitely one of
the most exciting and challenging programs our engineering team at College Park
has ever worked on.”— by Mary L. Jerrell, ELS
Disclosure: No sources for this story had any relevant financial
disclosures.
