View Full Version : Biomechanics of the sacro-iliac joint

Marcel Van Riel
08-17-1992, 07:46 PM

Dear Biomch-L readers,

In an earlier study we measured that lumbar lordosis does not increase
during pregnancy. The thoraco-lumbar spine becomes even straighter.
So, in pregnant women low back pain may not be ascribed to change of
form of the spine. Therefore we started to look at the sacro-iliac
joints, which as a consequence of pregnancy can be influenced by
laxity of ligaments leading to instability. Because our attempts to
relieve peripartum pain with the help of a pelvic belt at the level of
the trochanter were successful, we tried to explain this phenomenon by
means of a biomechanical model. Starting point is, that the predomi-
nantly flat sacro-iliac joint surfaces are vulnerable to shear loading.
Resistance against sliding can be obtained by course texture (we
measured a friction coefficient of ca. 0.3) and ridges and grooves.
These provisions only are useful when the adjacent joint surfaces are
pressed against each other. This brought us to "the sacro-iliac joint
compression paradigm". This includes a large number of muscles (e.g.
the gluteus maximus and piriformis muscles), ligaments (e.g. the
sacrotuberous, sacrospinal and dorsal and interosseus sacro-iliac
ligaments) as well as coactivation of leg, pelvic and trunk muscles
with special significance of the lumbar dorsal fascia. For load
transfer the concepts exist of the pelvic arc and the pelvic ring, the
latter including a role of the symphysis. In our study for the transfer
of large lumbosacral load to iliac bones and legs the symphysis does not
play a role.
Research is in progress to further validate and quantify the model. We
welcome contacts with colleagues in this field. Herewith we announce

"First Interdisciplinary World Congress on Low Back
Pain and its Relation to the Sacro-iliac Joint"
November 5-6, 1992
San Diego Convention Center

Experts deal with fundamental data, biomechanical and kinematic aspects,
visualization techniques and clinical applications. This conference
is an initiative of the School of Medicine, University of California,
San Diego and School of Medicine, Erasmus University Rotterdam.

For further information about this conference:
in U.S.A.: Office of Continuing Medical Education, 0617
UC San Diego School of Medicine
La Jolla, CA 92093-0617
Phone: int.1.619.5343940
Fax: int.1.619.5347672

in Europe: European Conference Organizers
P.O. Box 25327
3001 HH Rotterdam
The Netherlands
Phone: int.31.10.4133287
Fax : int.31.10.4147988

Looking forward to exchange research ideas,

Chris Snijders, Andry Vleeming, Jan-Paul van Wingerden and Marcel van Riel.
Department of Biomedical Physics and Technology and
Department of Anatomy
Faculty of Medicine and Allied Health Sciences
Erasmus University Rotterdam

Yours sincerely,
Marcel van Riel

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Marcel van Riel Phone:int.31.10.4087376
Biomedical Physics and Technology e-mail:riel@bnt.fgg.eur.nl
Faculty of Medicine and Allied Health Sciences
Erasmus University Rotterdam
PO Box 1738
3000 DR Rotterdam
The Netherlands
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