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Tuire Karaharju-huisman
08-25-1997, 06:42 PM
Dear all,

A few weeks ago I posted some questions about gait analysis. I got a few
answers which are posted here.
Thank you all for your help!
I hope these replys are useful for others too. If anyone still would like
to take part in the discussion, I'd be happy to receive more comments,
which I'd post later on.

Tuire :-)

Original posting:
Dear all,

We are two physiotherapists doing a study about gait parameters in
pathological gait. Before starting the data collection, we came up with
some important questions.

1) Measurement of leg length.
We are using the MacReflex system, by Qualisys, and Autogait for analysing.
For the analyse subject info is needed, including leg length. The autogait
manual doesn't describe the measuring method. We would like to discuss the
different guidelines existing for this specific measurement.

2) The length of the walkway.
In the litterature different walkway lengths have been used. Are there any
criteria published on this field (f.ex. minimum length, walkway lengths for
adults/children, disabled children...)?

Thank you for your help,

Tuire and Åsa

************************************************** *******

In past gait studies with which I have been involved, my colleagues and
I defined leg length as the vertical distance from the floor to the
greater trochanter.

Hope this is helpful.

Chris Miller
Bone and Mineral Lab
Krug Life Sciences/NASA JSC
Houston, TX 77058

************************************************** *****

The leg length measurement probably is the anterior
superior iliac spine (ASIS) to medial malleolus. It
depends on the method used by your system to calculate the
hip joint center and move the marker at the ASIS into the
volume occupied by the femoral head (or so goes the
theory--see Davis, RB III, Ounpuu, S, Tyburski, D, and Gage,
JR (1991). A gait data collection and reduction technique.
Human Movement Sciences 10, 575-587.). It does appear to
work reasonably well but we are using a VICON system.
Perhaps Qualisys could be contacted to give you a more
specific answer.

As to the walkway length, we have a calabrated volume of
about 3m long by about 1m wide and about 1.5m high. The
subject have 3m before and after this volume to establish
their usual pattern. Other labs I am familiar with have
different sizes but are in this general range. Smaller
than this and you risk including accelerating strides
before a reletively constant speed is achieved. Larger
than this and you may induce fatigue in your more involved
subjects. Best of luck.

Sincerely,

Michael Orendurff

************************************************** **

Measurement of leg length: most publications of gait study report their
leg length measurements from the greater trocanter to the floor;
bisecting the lateral malleolus. This method is widely used to
normalize step length and gait velocity.

The minimum length of the walkway can be determined, for each of the
categories you listed, as the minimum length required to include at
least two strides of each foot.

Please, visit our site at www.gaitrite.com. You will find it ineresting
and informative.

Please, e-mail back with your response, since I had difficulty in
locating your site for this return mail.

Regards
Constantin

************************************************** *

I recently saw your posting to the biomch-l server concerning the leg
length measures in AutoGait. For this particular software, the leg
length is determined by measuring the distance from the greater
trochanter marker to the ground in centimeters. This should be done
while the subject is in a quiet standing position (if possible) with as
normal a posture as possible. For some populations, this may be
difficult. If you are measuring severely pathological subjects, then a
different approach may be necessary. In this case, the distance between
the following markers would determine leg length:

thigh length (cm) = distance from greater trochanter marker to knee
marker

shank length (cm) = distance from knee marker to lateral malleolus
marker

foot length (cm) = distance from lateral malleolus marker to floor

leg length (cm) = thigh length + shank length + foot length

As for your other question concerning the length of the runway, the
runway should allow the subject to perform two full "normal" strides
before and after the required contact foot (minimum). This then would
allow them to achieve a more typical stride pattern to their everyday
lifestyle. Many researchers say that up to 5 complete strides should be
completed prior to foot contact on each side of the force plate. You
should determine a priori how many footfalls your population would need
to establish these typical stride patterns.

I hope that you have found this information helpful. I would direct you
to the following email address: sales@qualisys.se if you have any
further questions. Have a good day.

Sincerely,

QUALISYS, INC.

Andrew Mahar
Research Biomechanist




Tuire Karaharju-Huisman
St. Görans Barnsjukhus
Motoriklab, plan -1
S:t Göransgatan 141
112 81 Stockholm
Sweden
Tel: +46 (0)8 672 47 04
Fax: +46 (0)8 672 49 15
Email: Tuire.Karaharju-Huisman@kbh.ki.se