Determinants of Gait: What people said...

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.

Yours sincerley

Rico de Visser <rico@mbfys.kun.nl> 


Dear Rico, and anyone else interested,

Compass gait was a illustrative concept used by Inman and Saunders in the
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:

/teach-in/kinematics.html

.. 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. I wonder
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 the view
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?

Best wishes,

Chris

--
Dr. Chris Kirtley
Dept. Rehabilitation Sciences
The Hong Kong Polytechnic University
Hong Kong
Special Administrative Region of The People's Republic of China


I was interested to read Chris' comments on the Saunders et al gait
determinants. It would be timely, I think, to re-examine some of these
assertions in the light of 45 years of further research. We also have raised
the issue of the pelvic motion as a biomechanical determinant, but in our
paper we particularly question the role of pelvic axial rotation. We were
not the first, of course; Patricia Murray raised the same issue in the early
60s. Her observations suggested that pelvic rotation was highly variable and
in some cases not detectable during walking in healthy subjects. We found
that the synchrony of pelvic rotation and all other hip and pelvis movements
was random across our sample of 102 subjects.

I never actually followed up Gard and Childress' paper until now, but I also
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've personally given up teaching them now to my undergrads - I took the view
 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!

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.

Jeremy

  Jeremy Linskell
  Treasurer and Secretary, ESMAC
  Dundee Limb Fitting Centre
  Dundee, DD5 1AG, Scotland
  tel +1382-730104, fax +1382-480194
  email: j.r.linskell@dth.scot.nhs.uk
  web: http://www.dundee.ac.uk/orthopaedics/esmac 


Dear All,

Thanks again to Chris for bringing up a topic of significance.  "The major
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
his colleagues.

The title does seem a bit grand.  Inman simply tabulated those elements of
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) is
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.  These
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?

Yours Sincerely,

Larry Lamoreux
From 1963 to 1980 at the Biomechanics Laboratory
  of the University of California at San Francisco & Berkeley
Tel:  925-283-7718
Email:  LLamoreux@AOL.com 


Dear ladies and gentlemen
        Now,I am only reading abc books of biomechanics, but I could not help
talking something. I have practiced  a kind of gait for 8 years.( Chinese
kungfu__Taichi and Bagua).
        Besides COM, the inefficient practices include swinging arms according to
legs and pushing ground. I think that one of results of our traing is to
simulate  our  body COM move on wheels. Human have enough muscle_skeleton
and brain. The smoother someone move, the better is his Kungfu after
training years by years. Our brain and body know what are the efficient
positions of every skeleton and muscle according to some methods developed
by our ancient masters.The relaxation of muscle_skeleton at any training
time is very important. As a fight discipline ,it is strange that we do not
do any heavy and quick training. So our habitual gait has been
foundamentally changed. He can only get stiff inefficient gait if somebody
try to  purposely fix his arms and do not push ground without years of
taichi and Bagua training. We can move joints left_up right_down
alternately(pelvic and coccyx,  breastbone and ribs, backbone and ribs)
they are originally still when we become adults because human seldom use
them in most of human movements no matter what age.  Perhaps this is habit
of human.
        I am trying to setup a website for our group now. The website of
Dr.Kirtley is very good.
        Perhaps what I have talked is too trivial to clinic gait. sorry.

Best wishes
                                                Wang Chengzhi
                                                Apr. 10th,1998
student of MD.
computer science department
Tianjin university
People's republic of CHINA


We have followed the discussions on CGA concerning the 'Determinants of
Gait' with interest.  As Dr. Kirtley pointed out, we published findings
early last year in "Gait & Posture" that were not consonant with prevailing
ideas about the second 'determinant' of gait; namely, the influence of
pelvic obliquity (which we previously referred to as pelvic list until we
adopted the clinically preferred terminology) on the magnitude of vertical
movement of the trunk during normal walking.  We have also completed a
study related to the third 'determinant' of gait, the effect of
stance-phase knee flexion on the trunk's vertical displacement in normal
walking.  This work was presented at the 1997 North American Society of
Gait and Clinical Movement Analysis (NASGCMA) Meeting in Chicago and at the
1997 American Society of Biomechanics (ASB) Meeting in Clemson, S.C.  Knee
flexion during normal walking also does not appear to reduce the magnitude
of the up-and-down movement of the trunk, which is in opposition to
conventional wisdom concerning the third 'determinant'.  We have submitted
a paper concerning the effect of stance-phase knee flexion on the vertical
displacement of the body during normal walking but it has not yet been
accepted.

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
comments.

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
be undertaken.

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.

Back to FAQ