View Full Version : Re: trunk markers

Laura Malczewski
12-01-2003, 06:52 AM
These are the responses to my previous e-mail:
I am interested in measuring the amount of trunk "lean" in the
sagittal plane during running. I would appreciate anyone's advice as to the best
positions for the markers to describe the trunk segment.

Thanks to all who responded!
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.. ask to Moreno D'Amico , is the best expert in Italy
Alberto Leardini, DPhil
Movement Analysis Laboratory
Centro di Ricerca Codivilla-Putti
Istituti Ortopedici Rizzoli
Via di Barbiano 1/10, 40136 Bologna ITALY
tel: +39 051 6366522
fax: +39 051 6366561
email: leardini@ior.it
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Have a look on Syczewska's article, which was published on Clinical
Biomechanics, v.14, p. 384-388, 1999. The group uses a number of markers
placed along the spine to quantify spinal motions. Depending on the
variables you want to quantify you may discard some of them...
Best Regards

Prof. Dr. Andre Luiz Felix Rodacki
Departamento de Educacao Fisica
Setor de Ciencias Biologicas
Universidade Federal do Parana
R. Coracao de Maria, 92 - BR 116, Km 95
Jardim Botanico - Curitiba - Parana - Brasil
Fone 262-7574
FAX 362-3653
E-mail: rodacki@ufpr.br
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I pubished a paper in Clinical Biomechanics earlier this year (v18,
655-661) in which we differentiated hip and trunk kinematics during various
postural conditions. We used an electromagetic tracking system with senors
placed on the C7 spinous process, the base of the sacrum, and mid-thigh.
The trunk was defined by the sensors placed on C7 and the sacrum and the
digitized hip joint center. Hip flexion was defined by the sacrum sensor,
the digitized hip joint center, and the thigh sensor. I hope this helps.
Good luck.

Troy Blackburn, MS, ATC
Doctoral Candidate in Human Movement Science
University of North Carolina at Chapel Hill
Sports Medicine Research Laboratory
06-F Fetzer
CB #8700
Chapel Hill, NC 27599
Phone: (919)962-7187
Fax: (919)962-0489
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To my knowledge, the Plug in Gait (PiG) upper body model has
not been validated in any peer reviewed journal papers and therefore there are
no articles on repeatability of the upper body model. Below are
references to the PiG lower extremity model and then the full description of
the PiG model (lower and upper). Let me know if the information below
didn't transfer well via email.


Plug In Gait, Gait analysis software is based on the following journal papers:
Bell, A.L., Pedersen, D.R. & Brand, R.A. (1990). A comparison of the accuracy of
several hip center location prediction methods. Journal of Biomechanics, 23,
617-621.Davis, R., Ounpuu, S., Tyburski, D. & Gage, J. (1991). A gait analysis
data collection and reduction technique. Human Movement Sciences, 10, 575-
587.Kadaba, M.P., Ramakrishnan, H.K. & Wooten, M.E. (1987). J.L. Stein, ed.
Lower extremity joint moments and ground reaction torque in adult gait.
Biomechanics of Normal and Prosthetic Gait. BED Vol (4)/DSC Vol 7. American
Society of Mechanical Engineers. 87-92.Kadaba, M.P., Ramakrishnan, H.K.,
Wootten, M.E, Gainey, J., Gorton, G. & Cochran, G.V.B (1989). Repeatability of
kinematic, kinetics and electromyographic data in normal adult gait. Journal of
Orthopaedic Research, 7, 849-860Kadaba, M.P., Ramakrishnan, H.K. & Wooten,
M.E. (1990). Lower extremity kinematics during level walking. Journal of
Orthopaedic Research, 8, 849-860.Macleod, A. And Morris, J.R.W. (1987).
Investigation of inherent experimental noise in kinematic experiments using
superficial markers. Biomechanics X-B, Human Kinetics Publishers, Inc.,
Chicago, 1035-1039.Ramakrishnan, H.K., Wootten M.E & Kadaba, M.P. (1989). On
the estimation of three dimensional joint angular motion in gait analysis. 35th
annual Meeting, Orthopaedic Research Society, February 6-9, 1989, Las Vegas,
Nevada.Ramakrishnan, H.K., Masiello G. & kadaba M.P. (1991). On the estimation
of the three dimensional joint moments in gait. 1991 Biomechanics Symposium,
ASME 1991, 120, 333-339.Sutherland, D.H. (1984). Gait Disorders in Childhood
and Adolescence. Williams and Wilkins, Baltimore.Winter, D.A. (1990)
Biomechanics and motor control of human movement. John Wiley & Sons,
Inc.These references have information on kinematic and kinectic calculations, as
well as anthropometrics and repeatability of the model.The upper body model
has not been validated in any peer reviewed journal papers and therefore there
are no articles on repeatability of the upper body model.
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How are things going at UB? When i was at Penn State I looked at head and trunk
kinematics during stair negotiation. I was more concerned about the upper trunk
so my landmarks included C7, left and right acromion processes and the
suprasternal notch. I used the marker cluster method (see pictures below) and
digitized the anatomical landmarks with a calibration wand. Using this method
you would need to subtract off the normal standing position because the vector
from C7 to SSN will be pitched forward (this is only if you are looking at trunk
angle in the global coordinate system). We ordered the plate that made up our
trunk cluster from the Alimed catalog. You could use a lumbo-sacral marker
instead of the SSN, but we weren't sure if that would stay stable relative to
our cluster during movement. Let me know if you have any questions.

Kate Hamel, PhD
Assistant Professor in Residence
Department of Physical Therapy and Rehab Science
University of California San Francisco
Box 0625
San Francisco, CA 94143
415-353-7221 FAX
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How are you capturing your data? 3-D or 2-D? We have done some analyses
at NASA on this just to determine what kind of space requirements are
necessary for a treadmill on ISS. We are happy to get the deviation of the
trunk from the vertical, so we just use a marker on the shoulder top (where
you would balance a parrot), and the hip.

If you are interested in rotations, lean, and side to side motion, then you
will need to create a 3-D reference frame attached to the trunk. Let mw know
what you are thinking and I amy be able to help you more if you are still
looking for help.

John DeWitt
NASA Johnson Space Center Exercise Physiology Laboratory
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For model like Plug In Gait (Vicon) ther are four markers that define
the trunk: Between the clavicles on the superior aspect of the sternum, at
the xyphoid process at the inferior aspect of the sternum, at C7 and T10 on
the back. Trunk lean is sagittal plane flexion with respect to the global
xyz axis. Vicon calculates a spine angle that is the trunk segment relative
to the pelvis (2 ASIS, 2 PSIS).

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It is not so simple to answer to Your question in the sense that it really
does depend on the capabilities provided by the Movement Analysis system You
In fact we developed a complete protocol and a very specialised signal
processing algorithms in order to fully identify 3D spine morphology. This
protocol and feature extraction algorithms have been proved to provide
information and measurement comparable to X-Ray approach (both in the
frontal and in the sagittal plane) when normal weight people are measured,
while it should be managed with care when obese people are analysed
especially in the sagittal plane measurement because fat thickness at rachis
different levels could mask spine sagittal shape. The approach we developed
to correctly identify 3D Spine shape is based on the measurements of at
least 13 markers positioned on the following body landmarks:
11 on the spine starting from C7 to S3 every second vertebra
2 on the Posterior Superior Iliac Spine
The 2 markers on the PSIS allow to establish a subject linked co-ordinate
system to frame by frame correctly identify the frontal, sagittal and
horizontal subjetc's referred planes.
The 11 markers on the rachis should be considered as the necessary minimum
marker set to correctly identify 3D spine shape at a comparable level with
X-Ray information. In fact we proved no signal processing procedure can
provide reliable results for Spine clinical parameters extraction such as
Kyphosis Lordosis angles and Spine sagittal lean amount in relationship with
its shape, by using a smaller set of markers.
This is because to obtain such shape information signal smoothing and
derivatives assessment are necessary and this is a very difficult task when
very few noisy data point are to be processed i.e. at least 11.
We presented in the past a special automatic signal processing Smoothing and
Derivatives assessment procedure named LAMBDA[1,2,3] we compared with
best published on literature obtaining very good outcomes (...superior) on
biomechanical data to obtain velocities accelerations and even jerks
estimation from noisy markers trajectories. Indeed we needed to further
improve such signal processing algorithm [3] to obtain reliable shape
results from the 11 markers on spine.

To answer to Your question it firstly should be established what kind of
information You want to obtain. If in fact You only need some sagittal
spinal offset measurements (i.e. horizontal displacements with respect to
vertical line of some vertebra) a good solution could be to place a marker
on S3 vertebra determine the vertical line passing through S3 and then to
compute the horizontal distances with respect to this line. Added good
points in this case are the C7 vertebra and the apexes of thoracic Kyphosis
and Lumbar Lordosis, these latter two positions are different per each
subject and should be detected and marked by clinical inspection.
If You need more detailed information on Spine shape, so You need to use the
above described minimal set of 13 markers for trunk posture and pose. Of
course other markers have to be considered to detect legs movement during
running so this will be a high demanding task for the Motion analyser You
use. In particular a crucial step is for sure the tracking and labelling
one, when 13 Spine and pelvis markers are included in the model.
In our experience we had full 3D information on spine during walking but we
did not approach running yet. If Your opto-electronic system is able to
measure and correctly track the minimum 13 marker set or better a set of 27
markers or higher and obtain the measurements collected on a C3D file, give
me a feedback and we could agree a suitable protocol. In such a case in fact
Spine or a full skeleton model could be identified and You could send me a
C3D file of a running trial You acquire and I'll send You back what it is
possible to extract with our processing approach.
I've attached some of our publications [3,4,5,6] on the argument to provide
You some more details.

I hope this is something helpful to You.
Best regards

Sede Legale Via C.D. Spiga 10
65124 Pescara
Sede Operativa Via Aterno 154 (giÓ Via Salara 7)
66020 San Giovanni Teatino (CH)
C.F. - P. IVA 01457770681
Tel. (+39) 085-4463940
Fax: (+39) 085-4408450

[1] M. D'Amico and G. Ferrigno, Technique for the Evaluation of Derivatives
from Noisy Biomechanical Displacement Data Using a Model-Based
Bandwidth-Selection Procedure, Med. & Biol. Eng. & Comput. 28, 407-415,
[2] M. D'Amico and G. Ferrigno, Comparison between the More Recent
Techniques for Smoothing and Derivative Assessment in Biomechanics, Med. &
Biol. Eng. & Comput. 30, 193-204, 1992.
[3] M. D'Amico and P. Roncoletta, "A new self-adapted digital filtering
procedure for data smoothing and differentiation ", Proceedings of the XVIII
ISB (Inetrnational Society of Biomechanics) Congress, Zurich (Switzerland),
8-13 July 2001.
[4] M. D'Amico, G. D'Amico and P. Roncoletta, A 3-D Parametric Biomechanical
Skeleton Model for Posture and Spine Shape Analysis. In Research into Spinal
Deformities 3 (eds. A. Taguy and B. Peuchot) IOS Press 2002 Proc. Of 3rd
Congress of International Research Society of Spinal Deformities,
Clermont-Ferrand (France) 26-29 May 2000, pp365-369.
[5] M. D'Amico and P. Roncoletta: Baropodographic meaurements and averaging
in Locomotion and postural analysis. In Research into Spinal Deformities 4
(ed. T. B. Grivas) IOS Press 2002 Proc. Of 4 th Congress of International
Research Society of Spinal Deformities, 24-27 May 2002 Athens Greece, pp.
[6] M. D'Amico and P. Roncoletta: Joint Segmental Kinematic Trunk Motion and
C.O.P. Patterns For Multifactorial Posturographic Ananlysis. In Research
into Spinal Deformities 4 (ed. T. B. Grivas) IOS Press 2002 Proc. Of 4 th
Congress of International Research Society of Spinal Deformities, 24-27 May
2002 Athens Greece, pp. 149-152.
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What kind of system are you using? Most of my experience is with VICON.
positions we've used be of any help to you?

I'm a working on my Master's in Biomechanics and just started working for a
manufacturer in Canada. Our system might be usefull for you, as it isn't
limited by
outside cameras, electromagnetic fields or hardwiring.

If that sounds interesting, please drop me a line.


john brown
Special Projects Directror

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