The original posting is below, followed by the responses
biomech-l,
Has anyone used, or have knowledge of types and suppliers of
intracortical (bone) pins that are non-magnetic, such as perhaps
titanium?
This is for a project where a reflective marker triad set will be
attached to bone pins for motion tracking and MRI's may potentially be
taken.
Thanks,
Sarah Hummel
Steadman Hawkins Sports Medicine Foundation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Please visit www.amtbe.com for further information.
Dr Dimitri ASLANIDIS
AMS World Services
rue de la Nethen 14, Beauvechain
1320 Belgium
tel +32 478 296969, fax +32 10 862134, e-mail to: metallurgy@skynet.be
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Sarah,
I am not aware of non-magnetic pins. However, in our studies of knee
joint motion, we used 3.0 mm Apex self-drilling/self-tapping bone pins
(Stryker Howmedica). These pins are generally used with the Hoffmann® II
External Fixation System. Although our pins were stainless steel, it may
be that Stryker Corporation may have non-magnetic pins but you will have
to contact them for more information. For your information, the
disadvantage of titanium is that this metal has an extremely low modulus
of elasticity & low tensile strength. Therefore, pins have to be bulkier
than stainless steel in order to provide same rigidity. Since you may be
looking at static positions in the MRI chamber, this may not be an issue
however it may become an issue if you will be investigating dynamic
trials. Refer to Wheeless' Textbook of Orthopaedics, found at
http://wheeless.orthoweb.be/o16/67.htm for more info.
For references with respect to other pin research and Methodological
Concerns Using Intra-cortical Pins, please refer to the following
reference:
Ramsey DK, Wretenberg PF, Benoit D, Lamontagne M, Németh G.
Methodological Concerns Using Intra-cortical Pins to Measure
Tibiofemoral Kinematics. Knee Surgery, Sports Traumatology, Arthroscopy,
2003;11:344–349
I am also aware that markers were placed in on a 160 mm long, 4/5 mm
Schanz screw to measure vertebral motion.
James P. Dickey,Michael R. Pierrynowskib, Drew A. Bednarc and Simon X.
Yangd Relationship between pain and vertebral motion in chronic low-back
pain Clinical Biomechanics, Volume 17, Issue 5 , June 2002, Pages
345-352.
Sincerely
Dan
Dan K. Ramsey PhD
Post Doctoral Research Fellow
University of Delaware,
Department of Physical Therapy
301 McKinly Lab
Newark, DE 19716-2591
Tel: +1 (302) 831-4646
Fax: +1 (302) 831-4234
Email: dramsey@udel.edu
URL: http://www.udel.edu/PT/
Profile: http://myprofile.cos.com/DRam
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
We use ORTHOFIX, Bussolengo, Italy. I don't know the material. Sandra
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Sarah,
I'm a little confused by your application. Are you planning to collect
kinematic data while taking a MRI, do you want to leave bone pins in
after collecting kinematic data or do you have a different purpose?
If you're planning to take static MRI images and calculate the
kinematics from scan to scan (with repositioning between) you might want
to investigate the image processing system 3DVIEWNIX
(http://mipgsun.mipg.upenn.edu/). This software allows you to segment a
set of bones and calculates the geometric centroid and a principal axis
system. The software is capable of calculating the angle of rotation
and the centroidal translation from one bone relative to another (or
relative to the scanner) or you can make them on your own based on the
transformation matrices given from segmentation.
If you have any questions about my suggestion, please don't hesitate to
ask.
Stacie
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Hello Sarah
I know a variety of bone pins that are non magnetic. How can I help you
with getting the right kind for your project? If you wish you can call
me at Alta Surgical 906-228-9682
George J Iwanski
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Hi Sarah,
I saw your request for non-magnetic bone pins and was wondering if you
had any success locating some yet. I am an engineer with Orthofix and
know that our bone bones have minimal magnetic properties. If you are
interested in using them, please feel free to get back to me and I'll
try to help you out. What type of research will you be using them for?
You mentioned it was a motion analysis study, but could you give me a
little more information about it?
Thanks,
Kristen Duchac
Product Development Engineer
Orthofix, Inc.
Winston-Salem, NC
336.726.2964
-----------------------------------------------------------------
To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl
For information and archives: http://isb.ri.ccf.org/biomch-l
Please consider posting your message to the Biomch-L Web-based
Discussion Forum: http://movement-analysis.com/biomch_l
-----------------------------------------------------------------