CGA FAQ: How big does a gait lab need to be?
Dear all Analyzers,
I've just been having a private discussion with Peter Roche in Ballarat, Australia, about the minimum size
requirements for a gait lab. It struck me that this might be an interesting topic for general discussion. Here's
what I said to him...
Concerning gait lab size, I actually think this is really quite a complex topic. If you measure people walking
indoors they almost always walk with a significantly shortened stride (and reduced velocity). I think the
room has to be really quite massive for people to feel relaxed enough to stride out. Once you add force
platforms, the situation is even worse, because they inevitable worry about hitting the target.
One easy test you could do before agreeing to move would be to simply measure the time taken to walk a
known distance, counting the steps taken. Stride length = 120 x Velocity/Cadence and should around 1.5
m. If it's less then the room is too small. That said, most of us are interested in children anyway, so if that's
the case for your lab, you could do the same thing for children and see what you get. Use a nomogram to
estimate what stride length should be.
This issue is known about, but I suspect people avoid discussing it because many of us have labs that are
too small. The European standard, CAMARC, actually stipulated the minimum size allowed for an
accredited lab, but I don't know what this was - the standard never got adopted, as far as I know.
I was acutely aware of this problem in Hong Kong because of the inevitable space limitations. One lab I sent
my students to for the purpose of gathering normative data proved to be far too small, accentuated by having
the plates too close together (see: http://www.rs.polyu.edu.hk/gaitlab/fyp98). My own lab (see the VR at:
/gaitlab.html) was also on the small size - made worse by my decision to
mount a computerized posturography unit at one end of the walkway.
I'd be interested to hear what people say on this important topic. Perhaps you could tell us how big yours is
(pardon the phrasing!).
Chris
--
Dr. Chris Kirtley MD PhD
Associate Professor
HomeCare Technologies for the 21st Century (Whitaker Foundation)
NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation
Dept. of Biomedical Engineering, Pangborn 131 (office 105b)
Catholic University of America
Cardinal Station (or 620 Michigan Ave NE)
Washington, DC 20064
Tel. 202-319-6247, fax 202-319-4499
Email: kirtley@cua.edu
http://www.hctr.be.cua.edu/RERC
Clinical Gait Analysis: http://hctr.be.cua.edu/cga
Send subscribe/unsubscribe to listproc@info.curtin.edu.au
Dear All
Size matters !
I believe that most investigators sometime wished their lab to be "slightly" bigger. Here in Manchester we
have an 6m X 12m lab which is just the minimum space suggested by Oxford Metrics for out new 8 camera
Vicon system. This space is not too bad for most of our early poststroke patients (the other end looks really
far away to them), however this is not the case for our elderly controls.
It is unfortunate that I cannot really do anything about it. We are actually lucky that we have this space !!!
Giannis
Giannis Giakas PhD
Research Fellow in Biomechanics
School of Medicine
University of Manchester
ggiakas@hope.man.ac.uk
Dear all,
Edi reminds me that the height of the lab is important too - I'd agree (I'd like to know if anyone's done any
research on this)...
Hi Chris,
A quick comment on this - I remain convinced that ceiling height is a very important subliminal factor in this
too - it's not a simple length x width issue.
Also, at least with CP kids, my feeling has always been that force plate placement is generally a non-issue -
the chances of getting a L&R strike in an given trial is some small that it can be disregarded - so long as you
can get a number of decent L and R strikes (3-5 trials of each) for a given subject then you're OK. Multiple
plates increase the chance of getting a good strike on one plate in a trial - that's all.
Edi Cramp
Edmund Cramp,
Motion Lab Systems, Inc.
4326 Pine Park Drive, Baton Rouge, LA 70809 USA
+1 225 928-4248 (voice, 2 lines), +1 225 928-0261 (fax)
email eac@motion-labs.com
http://www.motion-labs.com
To all:
There is a direct science and of course luck in determining the gait lab size. The lucky part
is getting too much space. The science part is then determining what size lens to use.
For instance: a 4.8 mm lens on a 1/2 camera provides a 69 degree angle on your lens.
This calculates out to a 1 meter field of view for every .73 meters of distance of the subject
to the camera.
Hence the following can be used for a 4.8 mm lens
Field of View Distance to camera
1 meter .73 meter
2 meters 1.46 meters
3 meters 2.18 meters
6.0 mm lens provides an angle of 58 degrees or a D= .902 Field of View
8.0 mm lens provides an angle of 44 degrees or a D= 1.25 field of view
Therefore a long (10 meters long) and narrow (3 meters) wide using a Motion Analysis
HiRES with Zoom lens would mark out theior desired volume 4 meters long and .75
meters wide in the middle of the room, set their zoom lens to 4.8 on the sidewall mounted
cameras and for the long hall view used 8 mm to even 12.5 mm depending if foot markers
are being collected too. The HiRES EVa dynamic wand calibrates, linearizes the
cameras and lens and creates the lens/camera distortion mapping accordingly and then
data trials begin.
Please note that the above measurements are for 1/2 inch camera lens type. The
calculations change with a 2/3 camera opening for the lens.
I would be happy to fax or post our tables for interested parties.
Dan India
=============================
Daniel India, Group Vice President
Motion Analysis Corporation
3617 Westwind Blvd
Santa Rosa CA 95403
==============================
T: 847-945-1411
F: 847-945-1442
F: 916-314-2180 (Fax to PC)
Dan.India@MotionAnalysis.Com
Dear all,
I'm grateful to Jeremy Linskell from Dundee, who corrects me regarding the planned European accreditation
system (see below). I've just had a look at this site, and there is some quite interesting material there. For
example, there are "Golden Cases" describing expertly performed clinical motion analyses:
http://abcmale.ee.unian.it/DB_Golden_Cases/Prima_Golden_Cases.asp
Unfortunately, much of it is password-protected - you need to be an ABCMALE assessor to get in. I couldn't
read the Good Practice Guidelines, for example (which include the lab size requirements).
I'm sure many of you would like to know more about this accreditation system. It will be interesting to see
how it is received. Are there any similar systems being planned for laboratories elsewhere, I wonder?
Chris
--
I think that we must be talking about ABCMALE? This is a model
for an accreditation system, which incorporates Good Practice
Guidelines(GPGs). ESMAC has been commenting on the GPGs as part of
the Project User Group (i.e those with the actual clincial experience
who aren't actually being funded by the project!). We have tried to
make the GPGs as unprescriptive as possible i.e. lab of appropriate
size for the task (H&S etc.). The website for ABCMALE is
http://abcmale.ee.unian.it
Hope this helps
Jeremy
Jeremy Linskell, Clinical Engineer
Manager, Gait Analysis Laboratory
Co-ordinator, Electronic Assistive Technology Service
Tayside Orthopaedic and Rehabilitation Technology Centre
Ninewells Hospital, Dundee, DD1 9SY, Scotland
tel +1382-496286, fax +1382-496322
email: j.r.linskell@dundee.ac.uk
(backup email: j.r.linskell@dth.scot.nhs.uk )
web: http://www.dundee.ac.uk/orthopaedics/TRES/gait.htm
Haven't got much to add to the "How big is yours?" debate. Ours is 12m by 6m.
As with Gianna it would be nice if it were slightly bigger. The main problem
in our lab is not the instrumented analysis but the sagittal plane video. The
further the subject is from the camera the less of an issue parallax is. This
forces us to take separate video of the patient walking across the room but
the 6m width is not really far enough for our taller more able walkers to
exhibit their normal pattern.
If space is at a premium I think consideration needs to be given to layout.
Having a rectangular (or even square) box with the walkway running down the
long axis is incredibly wasteful. You don't need the corners, why not box
them off and turn them into examination rooms or offices. Go on give your
patients some privacy. Alternatively why not have the track running
diagonally across a square room ((2 times the bang for the same bucks).
Richard
Richard Baker PhD
Gait Analysis Service Manager
Musgrave Park Hospital, Stockman's Lane, Belfast, Northern Ireland, BT9 7JB
Tel: +44 1232 669501 ext 2155 or 2849
Fax: +44 1232 382008
Here the walkway is 39m long 2.8m wide and 2,82m high. The full distance is
used for EMG gait analysis.
Foir kinematics (VICON 5 cameras) the recording volume is 7 x 0.9 x 1.7m but
only 5 m are used for the sake of accuracy (noise at booth ends of the
field of view). Usualy the subject walks 4.7m before and 3.7m after the
field of view of the cameras.
No force plate used for gait analysis but 2 Kistler force plate for posture
and balance analysis.
YB
Mr. Yves BLANC, PT, Ph.D.
Laboratoire de Cinésiologie
Hopital cantonal Universitaire
1211 GENEVE 14 suisse
Fax xx 41 22 / 37 27 799
Phone xx 41 22 / 37 27 827
I agree with you this is a question I get asked all the time as well.
Most labs are small because they tend to be retrofits in to an older
building.
There are 2 factors to consider when answering the question.
First is the intended use of the lab (walking, running, sports
movement). Further compounded by the population i.e.. children, adults
or elderly subjects.
The 2nd is equipment requirements and field of view size. With our CODA
mpx30 we can create a slightly larger than 2 x 2 x 2 m field of view by
having the sensors 6 m apart. Then we have 15 m of walkway length to
allow room for even a slow run in adults and simple swinging movements
(tennis and golf with a short club). With our Selspot II the field of
view tended to be 2 x2 x 1.5 m because of the limited focal distance.
New lenses (wide angle) used in other systems like ELITE and Vicon do
allow use in smaller spaces.
In my view for all types of walking this is a good size. For running and
other sports you need more room length and height.
--
Alberto Esquenazi, MD
Director Gait & Motion Analysis Laboratory and
Regional Amputee Center
MossRehab
1200 West Tabor Rd.
Philadelphia, PA 19141 USA
Voice: 215 456 9470 Fax: 215 456 9631
Email: Aesquena@aehn2.einstein.edu
A Member of the Jefferson Health Network
Dear All,
Richard Baker <richard.baker@greenpark.n-i.nhs.uk> writes on Fri, 18 Feb
2000
..
>Alternatively why not have the track running diagonally across a square
>room ((2 times the bang for the same bucks).
..
Just a quick note about the diagonal walkway.
It will increase the length of the walkway, but it brings the cameras
closer to the calibrated volume (they go to the middles of the four
walls). The question is, what's more important. A longer walkway or a
larger calibrated volume.
As far as I remember on Biomch-l someone concluded that the latter is
preferred.
Gabor
--
Dr Gabor Barton MD CGA@gaitlab.demon.co.uk
Clinical Scientist
Gait Analyis Laboratory tel: +44 (0)151 252 5949
Alder Hey Children's Hospital fax1: +44 (0)870 052 1935
Eaton Road, Liverpool, L12 2AP, UK fax2: +44 (0)151 252 5846
Gabor Barton wrote;
> Just a quick note about the diagonal walkway.
> It will increase the length of the walkway, but it brings the
> cameras closer to the calibrated volume (they go to the middles of
> the four walls). The question is, what's more important. A longer
> walkway or a larger calibrated volume. As far as I remember on
> Biomch-l someone concluded that the latter is preferred.
Our cameras are positioned to give laboratory calibration volume
large enough to measure bilateral strides for an adult. I cannot
think of any gait-related scenario where I would require more. In
maximising its calibration volume a lab should remember to relate its
requirements to the resolution/accuracy it demands from its data (not
really a signifacnt problem for the newer systems).
Jeremy Linskell, Clinical Engineer
Manager, Gait Analysis Laboratory
Co-ordinator, Electronic Assistive Technology Service
Tayside Orthopaedic and Rehabilitation Technology Centre
Ninewells Hospital, Dundee, DD1 9SY, Scotland
All I am saying is that if the constraint is the walkway length, and
that makes someone to set up a diagonal walkway (~8m) in a 6m x 6m room,
then placing the cameras too close to the cal. volume can cause
problems. It can be difficult to set the cameras so that all markers
stay focused during the two strides (from shoulder down to foot).
--
Dr Gabor Barton MD CGA@gaitlab.demon.co.uk
Clinical Scientist
Gait Analysis Laboratory tel: +44 (0)151 252 5949
Alder Hey Children's Hospital fax1: +44 (0)870 052 1935
Eaton Road, Liverpool, L12 2AP, UK fax2: +44 (0)151 252 5846
Dear List members,
>From a practical point of view the diagonal walk-way doesn't work - I set up
a system in a lab some years ago where we ran the walkway diagonally across the
lab because we were short of space. In the end everyone felt that the small
gain in length was not worth the greater difficulty in locating decent camera
locations.
The problem here is that with a diagonal lab there are really only four
possible places to locate cameras - on-axis, at either end of the walkway -
or directly opposite the center of the walkway, normal to the force plates.
Generally these are not the ideal places for cameras studying gait.
In the end - when the user got a chance to move the walkway to a new lab -
the lab was rebuilt with a walkway down the center of the lab.
Regards,
Edmund Cramp,
Motion Lab Systems, Inc.
4326 Pine Park Drive, Baton Rouge, LA 70809 USA
+1 225 928-4248 (voice, 2 lines), +1 225 928-0261 (fax)
email eac@motion-labs.com
http://www.motion-labs.com
Dear Chris and others:
I happen to work in a lab where
Edi Cramp expertly placed the force
plates. I get two consecutive, clean foot strikes on the force plates
in about 50% of the walks
in kids with CP. This means the kids have to walk less and I have
to process less to get
reliable data. So I feel like placement IS important (we only have
two plates). Thanks Edi.
Michael
----------------------
Michael Orendurff, MS
Clinical Biomechanist
Motion Analysis Laboratory
Portland Shriners Hospital
MSO@shcc.org
John_ _Bickerstaffe <john.bickerstaffe@ukonline.co.uk>
to BIOMCH-L
Firstly, many thanks to everyone who responed to my original e mail. It
is
good to know there is back up around when you need it. I have summarised
the
responses in terms of the design of the room and design features which
are
peculiar to gait labs from the responses sent along with a couple of websites
and meetings we have had.Many thanks also go to Richard Jones at Salford
University who advised us recently on refinements to our plans.
The only factors I have not listed are those for force plates which are
set
into the floor as ours will be set into a walkway.The consesnsus appeared
to
say to design in a sufficiently large pit to accept force plates of various
specs now and in the future. Additionally you should ensure that the pit
allows the plates to be powered from beneath. Ducting should be available
allowing cabling to pass from the force plates to the control desk under
the
floor. An alternative to this is a raised floor.
Below is a copy of our requirements sent to our architiects recently.
Recommendations for Gait Clinic Build (5.12.06)
The following is a collation of findings from:
a) meeting with R. Jones Lecturer at Salford
University at the School of
Prosthetics and Orthotics on 8.11.06 with J. Schooling and J. Bickerstaffe.
b) the results of a question placed on the
international biomechanics
mailbase Biomechl which is subscribed to by all leading gait analysis labs
worldwide. I have summarised the answers provided.
c) Vicon website
d) Qualysis website
e) GCMAS
f) CMAS – clinical gait analysis standards
(2004), revised 2006.
Access
Should be unobstructed for the disabled.
Ceiling
The ceiling should be a tiled suspended ceiling, and will need to support
a
metal frame or butterfly hooks to suspend a calibration object if we plan
to
use a static calibration object (there should be a number of these).
The ceiling should be as high as possible.
We would like to have attachment points which we could attach a safety
beam
from the ceiling should we decide to install a beam in future for work
with
spinal injury cases. This would be placed directly over the force plates
capable of holding half a tonne.
If a safety harness is to be used then crossbeams should be installed in
the
ceiling perpendicular to the length of the lab. The optimum arrangement
is one
beam above the centre of the calibration volume and two beams positioned
five
feet on either side of the centre beam. This is to be used for spinal cord
injured walking, people with very poor balance.
Camera mountings
Ideally we would want to have various ways of fixing cameras
Scaffolding track around the room for cameras on which cameras are fixed
but
moveable. Has approximately 40cm of space at the posterior aspect of each
camera to allow for access and panning of camera.
From fixed mountings on the walls
From ceiling (or have points of attachment which would take a camera for
future use)
Windows
No skylights should be placed in the gait lab area. If windows are placed
in
the lab, you must provide a method for covering the windows to totally
block
out light (i.e., black drapes).
Lighting (none reflective)
Being able to reduce the lighting in the room would be beneficial to reduce
glare on screens and avoid further reflections. Recessed fluorescent lights
with diffusers are recommended. No lights should be directly over the force
plates. Light switches should be duplicated at the entrance door and at
the
control desk. Lighting should be even with no shadows high up on the walls.
This makes for better video quality.
Flooring
This should be none slip / none reflective, hospital blue vinyl, flooring
(and
not buffed).
Force plates situated in centre of room
Small conduit to run force plate cables through to the control desk.
Power points
As many as possible all double sockets – 20 around the room to allow for
various camera positions.
Power supply
Constant power supply, away from large power units and free from areas
of
vibration e.g. dental compressors.
If conduits are to be placed in the wall, you can position the video cable
conduits and electrical outlets in the following manner to provide
comprehensive coverage. You will need at least one electrical outlet (110-
120V) every six to eight feet. Double electrical outlets are preferable.
Treadmills should be powered by a separate AC power service.
Separate supply for force plates on floor and or on wall if surface mounted.
Power required for
EMG apparatus
Video camera system
Motion capture system
Force plates
Plinth
Treadmill
Ducting
Ducting around room for wiring at two heights with power outlets (double
sockets) every 3 feet.
Conduits for cabling
For leads from force plates to desk (solid rubber if to be surface mounted)
For mains supply to cameras at two levels
Ceiling for potential expansion into ceiling mounted cameras.
For camera cables
For video cables
You should provide camera cable conduits (minimum 1.5-2.0 inch diameters)
beginning at two feet above the floor surface. About eight of these will
provide the maximum flexibility in positioning the cameras - place one
close
to each corner of the room and one in the centre of each wall. Remember
that
the conduit down to the data collection system must accommodate all the
cables - this will need to be at least four to five inches in diameter.
Storage for spare cabling
Examination area
Patient examination area with an examination table and storage for supplies
such as tape, markers, electrodes, etc. This area is often used as patient
changing area.
This should be attached to the subject analysis area so that people can
walk
from the examination area to the data collection area. This area should
have
some storage for electrodes, markers and tape. This should be wheelchair
accessible with a sink available.
Doorways
The doors should be wide enough for wheelchair access.
The examination area should be patient friendly and offer privacy with
a
screened area.
Heating
Many gait related tests are performed with a minimum of clothing on the
subject so it is important that the laboratory area is maintained at a
comfortable temperature for the subject during the testing.
Computer Network (LAN)
It is important to plan for the computer network when the lab is built.
While
it is possible to use a number of different LAN types we recommend
100MHz "Twisted Pair" with a local hub or switch for the best reliability
and
speed. Since virtually all the computers and printers in the lab may be
connected to the LAN network it is important to provide plenty of LAN
connections within the gait lab and any connecting offices or work areas.
Make
sure that LAN cables can be run between the various lab areas. We strongly
recommend that the gait lab maintain its own network switch or hub within
the
lab for reliability.
Desk space
For trust PC / Qualysis work / wide screen
Force plate readout
Video screen
EMG equipment
Number of power sockets and whereabouts every two metres
Video cameras X 3
Treadmill supply X1
Motion analysis cameras X 6
Force plates X2 (in floor and wall mounted)
PC supply X1
Printer supply X1
Up to four monitors X4
All cabling from PCs, video, force plates, QMT cameras, EMG to meet at
control
desk. Have facility to incorporate other cameras / + power requirements.
All conduits to be 50% larger than original estimate to allow for expansion.
Cover for force plates.
Hope this is helpful to everyone on the mailbase and thankyou again for
your
support.
John Bickerstaffe
Orthopaedic Triage Dept
Tameside and Glossop PCT
UK
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