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Summary: Terminology for pelvic rotation in frontal plane

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  • Summary: Terminology for pelvic rotation in frontal plane

    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.


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

    My original posting:

    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.

    >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

    >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

    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
    LEVANGIE. F.A. DAVIS, 1992.

    Hope this helps.


    ************************************************** *********
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    * 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 *
    * *
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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
    physicians hardly ever note same in their patient reports.

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

    Bob Dubin, DC (

    >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

    >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 ---
    Tel: Intl + 612 646 6549
    Fax: Intl + 612 646 6601

    >From Arthur Hsu (

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

    However, the first situation should be called "LEFT UPWARD LATERAL PELVIC

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

    >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

    >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

    End of replies.