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Guido Pagnacco
04-20-1996, 07:04 PM
Dear fellow BIOMCH-L subscribers,
Here are the replies I got in response to my query (see below).
Many thanks to everyone who contributed. I will add to the summary any
more replies I get in future.

Guido Pagnacco

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Guido Pagnacco e-mail: gpagn001@magnus.acs.ohio-state.edu
The Ohio State University Phone : (614) 538-9600
Mechanical Engineering Dept FAX : (614) 538-9600
Room 2097 Robinson Lab
206 West 18th Ave
Columbus, OH, 43210-1107
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(Original Query 04-08-96)

Dear all,
I am interested in the use of force plates for rehabilitation purposes.
Searching several journals I have found many papers about gait analysis, but few
examples about rehabilitative use of force plate systems. Can any of you kindly
provide me with some references or examples on this subject?
Thank you in advance. I will post a summary in a couple of weeks.

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(Replies)

From: Frank L. Buczek, Jr.

Dear Mr. Pagnacco,

You pose a very interesting question regarding the use of force plates
in rehabilitation. Although I have no references to give you, I can
tell you that here at the Santa Rosa Biomechanics Laboratory, we use
force plate information in several ways to assist us in the gait
analysis portion of our work.

The ground reaction forces (GRFs) alone can tell us much about the use
of the lower extremities and assistive devices during movement. If
bilateral GRF for foot contacts show peak vertical forces well below
body-weight, then we know that the upper extremities, via assistive
devices, are being used for substantial support during gait. If the
antero-posterior GRF show typical patterns with reduced magnitudes for
foot contacts, then we know that at least a remnant of normal gait is
present. If the antero-posterior shear forces are directed
posteriorly for crutches and canes, then we know that these devices
are used more for support than for forward propulsion.

As you are no doubt aware, when force data are combined with kinematic
and anthropometric data, net joint moments and powers can be derived.
We use the joint moment information to identify and quantify excessive
loads on muscles groups due to disadvantageous joint kinematics (e.g.,
excessive knee and hip flexion during stance phase). Finally, the
joint power information is used to describe the strategies that a
patient is using to move, particularly with regard to effective forward
propulsion. In combination with the GRF data mentioned above, we are
able to piece together a comprehensive picture of the movement
strategies currently used. This information is presented to our
Medical Director and to referring physicians during patient care
conferences. Here, we discuss the implications of various therapies
and surgical alternatives, paying special attention to possible
disruption of current strategies in the pursuit of more normal
strategies. I do not believe our analyses would be as pertinent with
kinematic data alone.

Finally, we also use the force data to quantify aspects of balance
during "quiet standing." A literature search on "posturography" or
"stabilograms" may be useful for you here.

Please let me know if I can be of further assistance.

Frank



From: Howard J. Dananberg, DPM

Hi Guido,

I am a podiatrist in New Hamshire and I have been using vertical force
analysis systems to treat patients which chronic lower back pain for 14
years. I am currently using the F-scan system by Tekscan from Boston.

I believe that the key to using these systems is as follows. Overview:
Since walking is a process in which we attempt to pull ourselves (using the
swing limb, momentum and then gravity) over the weight bearing limb, then
the weight bearing foot must serve as a sagittal plane pivot. In each
segment (rear, mid and forefoot), the ability to transfer weight efficiently
to a support surface is dependent upon the ability to achieve the most
vertical alignment at the period when peak weight transfer should occur.
This also correlates well with the autosupportive ability of the foot and
lower extremity as described by Bosjen-Moller (J of Anat, 1978-79) and JH
Hicks (J of Anat. 1954-55).

A classic normal vertical force curve is the double hump appearing graph.
If the heel and forefoot areas are viewed in addition to the aggregate
curve, the ability to view peak loading of each aspect is easily seen.
Comparison of the slopes of these curves yields much to the understanding of
how they move over each side during single support phase. Using custom foot
orthotics, these "curves" can be manipulated to more normal appearance. The
affect of this is outstanding. In 1990, two colleagues and I published an
outcome assessment type study of patients at medical endpoint for chronic
postural pain (lower back pain, etc.). They were followed up at the two
year point and 77% were found to be 50-100% improved via the method of
treatment described above.

If you are interested in more information on this subject, I would be happy
to forward some papers to you. I would also be happy to discuss this
concept in more depth via e-mail.

Regards,

Howard J. Dananberg, DPM



From: Brian L. Davis, PhD

Hi Guido

We installed a couple of AMTI forceplates in a treadmill here and then
developed a system for providing real time feedback to amputee patients
while they walked on the treadmill.

Let me know if you need more info.

Regards, Brian



From: Jonathan Dingwell, M.S.

Guido:

I take it you just might be working for Dr. Berme there?
Anyway, I did my master's work at OSU and at the Cleveland Clinic working
on developing real-time feedback software for an instrumented force plate /
treadmill device that Dr. Brian Davis at the Cleveland Clinic designed.
we presented the results of those efforts at the CSB and ASB conferences
(Canadian and Amer. Soc. Biomechanics) in 1994. The work has since been
submitted for journal publication, and will appear as a technical note in
May 1996 volume of the ASME J. Biomechanical Engineering, and at some point
in the future in Orthotics and Prosthetic Internatinal (they've accepted the
article, but haven't said when it will appear yet). My 1994 Master's thesis
should also be available somewhere, but that's a lot more reading.

Good luck.

Jon D.



From: Chris A. McGibbon (Ronny) PhD

Dear Guido,

My colleques here at the Mass General Hospital Biomotion Lab use force
plates, in conjunction with a whole body motion analysis system, to study
balance and posture - more specifically - to better understand vestibular
hypofunction and other vestibulopathy and for quantitating balance
impairment before and after rehabilitation. The methods involve, in their
simplist form, comparing the motion of the body's center of gravity
(kinematics and anatomical model) to the center of pressure measured by the
force plate. The technique is generally known as phase plane analysis. A
good reference for these studies can be found in:

Benda BJ, Riley PO, Krebs DK, "Biomechanical relationship between center of
gravity and center of pressure during standing" IEEE Trans Rehab Engng,
Vol.2, 1994, 3-9.

Riley PO, Mann RW, Hodge WA "Modelling the biomechanics of posture and
balance" J Biomech Vol. 23, 1990, 503-506.

Best of luck.

Chris A. McGibbon (Ronny) PhD