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rhinrichs97
04-12-1995, 04:28 AM
Dear Colleagues:

A couple of weeks ago I posted a question about terminology for rotation of
the pelvic girdle in the frontal plane. Thanks to all who replied. I have
included my original posting as well as the replies below. Two people
referred me to Inman's book "Human Walking" in which the rotations are seen
as "clockwise" or "counterclockwise" as viewed from the front of the
subject. Others preferred to include the terms "hike" and "drop" to clarify
when a given hip is moving up or down, respectively. Two people preferred
"left lateral tilt" to be when the left hip drops relative to the right.
None preferred the opposite, that is, none said that "left lateral tilt"
was when the left hip is raised relative to the right. Clearly, I did not
find clear cut agreement on what to call this rotation. Any additional
responses would be appreciated. Thanks again to all those who replied to my
original posting.

--Rick

Richard N. Hinrichs, Ph.D.
Dept. of Exercise Science
Arizona State University USA
(1) 602-965-1624 (office)
(1) 602-955-8108 (fax)
Hinrichs@asu.edu (email)

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My original posting:
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I have noticed that there is inconsistency in the definition of left lateral
tilt vs right lateral tilt of the pelvic girdle. Some textbooks say that
LEFT lateral tilt is when you RAISE the LEFT side and lower the right side.
Others say that LEFT lateral tilt is when you and LOWER the LEFT side and
raise the right side . This latter definition makes more sense to me but I
would like to know what the rest of you think and if you could provide a
reference for your opinions, I would greatly appreciate it. I will submit a
summary of the replies I get. Thanks for your input.

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Replies:
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>From Ian Stokes:

Yes, we call ourselves biomechanists but there are some very
fundamental concepts and definitions that we have not got straight
yet! The problem with pelvic tilt is that it is not adequately
defined in terms of what it is, let alone the sign convention
problem which is the essence of the question you raise.

1. Ideally we should have terminology that distinguishes
between position and orientation ('pose' according to Herman
Woltring, but this term has not really caught on), and
motion - rotation and displacement. Words like 'tilt' get
used for both.

2. To define both of the above we need an axis system. If we
could define an anterior posterior axis of the pelvis, then
tilting motion would be rotation about that axis. The sign
convention would presumably follow the right-hand thread
rule for a right-hand axis system. The ISB and others are
wrestling with axis system definition for the human, but
consensus seems to be hard to achieve!

I hope these thoughts are helpful.

Ian Stokes
University of Vermont, Department of Orthopaedics and Rehabil.
Burlington, VT 05405-0084, USA
Phone: (+1) 802 656 2250 fax: (+1) 802 656 4247

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>From Peter V. Loubert:

According to kinesiological conventions, neither of the definitions that you
cite are adequate. Lateral tilt consists of two different directions of
displacement of the pelvis in a frontal (coronal) plane: namely, hip hike,
and hip drop. Lateral tilts are named according to the side of the pelvis
that is being elevated or dropped the greatest distance in space, presumable
the non-weight bearing side. The axis of rotation for these motions is an
anterior-posterior axis through the contralateral (weight bearing) hip
joint. For example, if you stand on your right foot and raise the left side
of your pelvis, that would be called a LEFT HIP HIKE. If you were to stand
on your right foot and lower the left side of your pelvis, that would be
called a LEFT HIP DROP. Both the hip hike and hip drop are types of lateral
tilt, and both the left hip hike and left hip drop are left lateral tilts.
To describe an example in the context of a functional activity, consider the
frontal plane motions of the pelvis during gait. As weight is transferred
from one foot to the other during the period of double support, the center
of gravity of the body is shifted toward the side that is at the beginning
of its stance phase. As body weight is transferred, and continuing beyond
the midstance event of the weight bearing side, there is a modest amount of
hip drop. That hip drop would be named according to the swing (non-weight
bearing) side, and would be occurring around an A-P axis throught the hip
joint of the stance (weight bearing) side.

Conventions for naming forward and backward rotation of the pelvis are
similar.

One of the reasons that lateral tilts are sometimes difficult for people to
figure out is that they describe displacements of the pelvis in space. They
do NOT describe joint motions, as is usual for most descripters of kinematic
displacements of body parts.

A good reference to look at would be the textbook JOINT STRUCTURE AND
FUNCTION: A COMPREHENSIVE ANALYSIS, 2ND EDITION. C.C. NORKIN AND P.K.
LEVANGIE. F.A. DAVIS, 1992.

Hope this helps.

Pete

************************************************** *********
* *
* Peter V. Loubert PhD, PT, ATC *
* Associate Professor of Physical Therapy *
* Department of Health Promotion and Rehabilitation *
* Central Michigan University *
* 134 Pearce Hall *
* Mount Pleasant, MI 48859 USA *
* *
* Voice: (517) 774-2396 *
* Fax: (517) 774-2908 *
* Email: Peter.V.Loubert@cmuvm.csv.cmich.edu *
* *
************************************************** *********

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>From Bob Dubin:

I have been a practicing DC for 20 years now.

A left lateral tilt means that the pelvis is tilted left. For the
uninitiated, that would mean left side lower than right side.

Matter of fact, pelvic tilt is so visible when it occurs, one wonders why
the
physicians hardly ever note same in their patient reports.

Where is this argument coming from? The very literature which describes
these
conditions? No wonder there is such confusion among the physicians regarding
the appropriate treatment of low back pain!

Bob Dubin, DC (drdubin@calon.com)

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>From Nick Stergiou (STERGIOU@OREGON.UOREGON.EDU):

The book "Human Walking" by Inman, makes a very clear pont about LLT.

Nick Stergiou
Biomechanics Lab
Dept of EMS
Univ. of Oregon

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>From Jack Crosbie:

I was interested in your posting; it is a problem that I too have been
struggling with. The solution that I have used, such as it is, is to firstly
define an axis system located in the pelvis, then use Inman's convention (in
"Human Walking") for naming rotation about the anteroposterior axis as
pelvic list, with positive list involving counter-clockwise rotation of the
pelvis as viewed from the front. I know that such a naming convention is
rather arbitrary, but at least it keeps the movements tidy.

Best wishes,

Jack Crosbie
School of Physiotherapy
University of Sydney
--- o O o ---
J.Crosbie@cchs.su.edu.au
Tel: Intl + 612 646 6549
Fax: Intl + 612 646 6601

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>From Arthur Hsu (arhsu@hsc.usc.edu):

I think both movements were correctly described as left lateral pelvic tilt.

However, the first situation should be called "LEFT UPWARD LATERAL PELVIC
TILT" and the second the "LEFT DOWNWARD LATERAL PELVIC TILT".

Arthur Hsu, Ph.D., PT
Dept Biokinesiology and Physical Therapy,
University of Southern California.

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>From Ron DeSandre, DC

I interpret the side (R or L) designation denotes the side it has gone
inferior on.

I also add the wording that it is inferior or lower on..... to make it
absolutely clear.

Hope this helps,
Ron DeSandre, DC
Carpinteria, CA
DrRono@aol.com

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>From Steve Hill:

In three-dimensional gait analysis, we refer to coronal (or frontal) plane
pelvic motion as "pelvic obliquity". Typically, this motion calculated
from anatomic markers on the ASIS's and the sacrum or PSIS's. It is usually
plotted with respect to the laboratory coordinate system, or with respect
to the line of progression. It is customary to say that pelvic obliquity
shows that the pelvis is, for example, "up on the right". What I call the
"Say it if it's so, Ethel" approach. ; )

The term "pelvic tilt" is generally reserved for use with respect to
anterior pelvic tilt: pelvic motion in the sagittal plane (again, using the
ASIS's as the anatomical references.)

D. A. Winter, in his text "Biomechanics and Motor Control of Human Gait:
Normal, Elderly and Pathological" (1991), defines pelvic obliquity as "the
angle of the pelvis in the frontal plane (normal to the plane of
progression) between the horizontal and the angle of the left and right ASIS
(or identical landmarks on the left and right side of the pelvis.)"

D. H. Sutherland discusses pelvic obliquity in his book "The Development of
Mature Walking" (1988) in terms of the rise of the anterior superior iliac
spines. "If the marker on the right is higher than that on the left, pelvic
obliquity is recorded as either 'up' for the right side or 'down' for the
left, and vice-versa."

J. Perry, in her book "Gait Analysis Normal and Pathological Function"
(1992), uses the terms "pelvic hike" and "pelvic drop" to refer to abnormal
pelvic motion in the coronal plane. Pelvic hike "indicates lateral elevation
of the pelvis above the neutral axis. Pelvic drop, conversely, implies
descent of the pelvis. This is differentiated into contraleral drop and
ipsilateral drop."

S. Ounpuu, it the "Terminology for Clinical Gait Analysis (Draft #2)" for
the AACPDM Gait Lab Committee (1994) defines it, "Coronal Plane Pelvic
Elevation (Rise)/ Depression (Drop): Motion of the medial-lateralaxis of the
pelvis as seen by an observer positioned along an anterior-posterior axis of
the pelvis."

I still didn't say what "right lateral tilt of the pelvic girdle" is, but
if it is meant to say right up or right down, it clearly is only and
arbitrary convention. Naming the side (L/R) and
where it goes (up/down) helps avoid confusion. By the way, the three books
listed are all excellent resources for the researcher in gait.

I hope this helped. Yours Truly,

Steve : )

O (o)xx
< ) \_ |
( / | \
/ \ / | \
< L ___ ___
_____________________________
Stephen W. Hill, B.Sc.
Kinesiologist/Administrative Director
SIU Motion Analysis Laboratory (1420)
Instructor of Clinical Surgery
Southern Illinois University School of Medicine
751 North Rutledge Street
Lower Level, Suite 0300
Springfield, IL 62702 USA
phone: (217) 782-6556
fax: (217) 782-7323
e-mail: shill@surg800.siumed.edu

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