Dear list members,
I'm an orthopedic resident. The item of my research is stiffen gait
patterns. I have heard something about a gait pattern "compass gait". The
collegue who told me about this could only tell me that it was 'stiff
gait'. After a search in the libary I found nothing about this gait type
So please is there somebody who can tell me more about this and are there
some references to this particular gait type.
Rico de Visser <firstname.lastname@example.org>
Compass gait was a illustrative concept used by Inman and Saunders in
first edition of their book, Human Walking. It was used to explain their
so-called "Determinants of Gait". If you can't get access to the book, you
can see the figures on the CGA page at:
.. just don't tell the publisher! ;-)
I was initially sending this to you personally, but I thought the whole
subject of the determinants might be worth discussing on the list. I don't
know whether any of you noticed Dudley Childress and Steve Gard's recent
paper in Gait & Posture, casting doubt on the Pelvic List determinant?
The whole idea of the Determinants seems to me increasingly bizarre.
how Inmann and Saunders came up with them, and why they gave it such an
important-sounding name. I appreciate their importance (or at least some of
them) in energy conservation, but this is hardly the most fundamental aspect
of gait (is it?).
I've personally given up teaching them now to my undergrads - I took
that there are far more important things to include in the curriculum. But I
confess, I felt like I was committing some sort of crime by not "doing" them!
Anyone want to respond - either for or against the Determinants?
Dr. Chris Kirtley
Dept. Rehabilitation Sciences
The Hong Kong Polytechnic University
Special Administrative Region of The People's Republic of China
I never actually followed up Gard and Childress' paper until now, but
find no relationship between range of pelvic list and vertical displacement
of the CoM with our sample. One possible reason for these anomalies may
relate to the way in which pelvic motion has been measured. The projected
plane technique (where the 3d movement is visualised as if it occurred in a
single plane, viewed from in front, above and from the side) tends to
double-dip on some movements, thus contemporary measurement processes arrive
at somewhat different values than the classic papers. Because of this,
movements which appeared substantial and consistent using a series of what
are essentially two-dimensional techniques, become less so when treated as
simultaneous three-dimensional motions.
Jack Crosbie <J.Crosbie@cchs.usyd.edu.au>
I present them purely as an illustration of the complex interactions
required to achieve a smooth energy efficient gait. When I am
lecturing to visiting students who are only getting a brief
introduction to cga it helps get across the importance of
indentifying the primary causes of gait abnormalities in diagnosis. I
think that a teliological approach to understanding gait is unlikely
be useful for clinical practice and even for research it is likely to
be more use to anthropologists than bioengineers/kinesiologists.
Treasurer and Secretary, ESMAC
Dundee Limb Fitting Centre
Dundee, DD5 1AG, Scotland
tel +1382-730104, fax +1382-480194
Thanks again to Chris for bringing up a topic of significance.
determinants in normal and pathological gait" by Saunders, Inman and Eberhart
was published in the J. Bone & Jt. Surg., 35-A(3):543-558, 1953. The ideas
were basically Inman's, I think, and Saunders name is reported to have been
added so he would have justification for attending a desirable conference with
The title does seem a bit grand. Inman simply tabulated those
gait that can be used to make the path of the center of mass smoother than it
would be for a rigid-legged "compass" gait. I think the paper has been
detrimental to our understanding of fundamental principles of gait because it
implies that the the goal of all these elements, or "determinants," is to
minimize the vertical oscillation of the center of mass (COM) during walking.
I think that is a fallacious notion. If it were desirable for us to walk
without any vertical oscillation of the COM, it certainly would be possible.
There are plenty of degrees of freedom in the pelvis and lower limbs to allow
walking without vertical oscillation. That suggests to me that a certain
amount of vertical oscillation must be desirable.
Consider that, in walking, the supporting ground reaction force (GRF)
vertically below the center of mass only at four instants during the gait
cycle: in the middle of each double-support period, and in the middle of each
single-support period. The rest of the time, the GRF is inclined either
posteriorly or anteriorly. If the GRF is inclined posteriorly, then there is
a shear component that decelerates the COM; if anteriorly, then there is a
shear component that accelerates the COM.
In other words, the center of mass of the body must speed
up and then slow
down again twice during each steady-state gait cycle. Vertical oscillations
of the COM are optional, but cyclic changes in velocity of the COM are
mandatory. If we are looking for a fundamental, underlying fact that governs
the dynamics of walking, this is it.
Cyclic changes in velocity mean cyclic changes in kinetic energy.
cannot be avoided. Therefore it is desirable to have suitably phased changes
in potential energy to keep the total mechanical energy of the body as uniform
as possible. When the COM slows down, it is desirable to have it also rise to
a higher elevation; when the COM speeds up, it is desirable to have it also
drop to a lower elevation. This exchange of kinetic and potential energy is
something like that in a pendulum.
I hope the above argument explains my frustration with the notion of
minimizing vertical oscillation that I believe was implicit in the "Major
Determinants" paper. My next question: Is the notion of "Lift Work" (ie, the
sum of the rises in elevation of the COM from trough to peak is a measure of
the work that must be done to walk) that has long been encountered in the
physiology literature a valid, or even pedagogically useful, concept? Or is
it, like the "Major Determinants," a concept that clouds the issue by
confusing an effect with a cause?
From 1963 to 1980 at the Biomechanics Laboratory
of the University of California at San Francisco & Berkeley
student of MD.
computer science department
People's republic of CHINA
The original purpose of our research was to examine issues of foot
clearance that occur when persons with lower limb amputation walk on
artificial limbs. We did not set out to question the 'determinants' of
gait. However, when we examined the data---our data and the data of other
investigators---we found that it did not support the idea that the second
and third 'determinants' reduced the energy of walking by reducing the
magnitude of vertical movement of the trunk. We agree with Dr. Lamoreux's
The 1953 paper by Saunders, et al. doesn't present kinematic data to
support the six 'determinants' of gait. Nevertheless, these six
'determinants' of gait are routinely taught in many educational facilities
as if they are firmly supported concepts. We believe the peak-to-peak
magnitude of the vertical movement of the trunk during normal walking comes
primarily from the inverted-pendulum-like movement of the body, much as
suggested by R. McNeil Alexander, even though the actual trajectory is
altered by shock absorption and other actions of the foot, ankle, knee,
hip, and pelvis, particularly during the time when load is rapidly being
transferred from the trailing to the leading leg during double support.
The reason neither pelvic obliquity or stance-phase knee flexion influence
the magnitude of the vertical excursion of the body very much in normal
walking has to do with the timing of these movements with respect to the
trunk's vertical displacement waveform. Pelvic obliquity and stance-phase
knee flexion are maximum near the time of toe-off. By the time the body
reaches its peak vertical position the pelvis is nearly neutral and stance
leg knee flexion has almost disappeared.
We, and those who have responded so far on CGA, are not the first persons
to question the assumptions associated with the six 'determinants' of gait.
Murray, in her paper "Walking Patterns of Normal Men" (JBJS, 1964) stated
with regard to pelvic rotation (first 'determinant') that, "The absence of
pelvic rotation in some of our normal subjects suggests that this is not an
obligatory element of normal gait, but rather a convenient excursion,
available when walking and, perhaps, attitude demand it." Winter (Phys
Ther, 1983) was critical of the idea that stance-phase knee flexion reduced
energy cost by decreasing the vertical motion of the body, and concluded
that the generally held opinion that stiff-legged stance is more energy
consuming than normal stance does not appear to be valid. Vaughan and
Sussman, in the book "Current Issues in Biomechanics" (1993), attribute the
popularity of the six 'determinants' of gait to their logical appeal,
through which the complexity of gait is described with six movements that
all share a common purpose: to decrease the vertical and lateral excursions
of the body's center of mass in order to minimize the energy expenditure of
walking. Vaughan and Sussman pointed out that very little rigorous work
has gone into testing the theory of the six 'determinants'. They suggested
that testing and examination of new theoretical concepts of walking need to
We enjoy CGA and commend Chris Kirtley for developing it and for
encouraging lively and informative discussions on interesting topics. The
medium is powerful and has much potential for education and for
collaborative efforts. Even though we don't often participate directly in
the discussions we still are influenced by them.
Steven Gard, Ph.D., and Dudley Childress, Ph.D.
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