PDA

View Full Version : Summary Re: Clamping Tendons



Kevin Hollander
02-06-1995, 10:49 AM
Hello,
As promised, here is the summary of responses to my orginal
question conserning the clamping of tendons in tension. I would like
to thank everyone that responded.

Thank You.

Kevin Hollander

Dept. of Mechanical Engineering
University of New Mexico
email - kevinh@pliers.unm.edu


++++++++++++Original Message+++++++++++++++++++++++++++++++++++++++++++ +++
Hello,

I am planning to do some mechanical testing of tendon specimens
and I was wondering what would be the best method for clamping the ends
of the tendon. I am interested in clamping as little of the ends of the
specimens as possible and I need to load it to at least 50% of its
ultimate strength. Through my literature search I know of a couple of
ways but I was curious as to your opinions on the subject. I will be
glad to list a survey of the responses.

Thank You
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++


i have done quite a bit of tendon tensile testing, and for each specimen,
we generally leave a bone fragment attached at the attachment sites. we
then use this to put into some grips which hold the bone rather than the
tendon.

this was done at the Noyes-Gainnestras Biomechanics Laboratories in case
you have already read about it. if you have any other questions, just ask.

matt rupert
university of cincinnati
rupertmp@ucunix.san.uc.edu


Hello Kevin.

i worked with Dr.Kato, who did his Ph.D.on replacement materials
for a tendon/ ligament...

The tendon is best tested with its ends left attached to the muscle and bone.

A small piece of bone is easy to grip at one end. At the other end the muscle
can
be gripped using a rough-surfaced clamp with a tissue paper or thicker paper
between the
specimen and the clamps to prevent slippage. SLippage can also be monitored in
different
ways - usually from the output load/displacement curve, although this is not
always very
reliable. In order to maintain the wet state while testing, clamps that have a
rough surface
and a cloth or paper between the tendon/muscle and clamps is usually good
enough. This method
can also be used to grip the tendon itself if desireable to separate it from
its surrounding
tissue.

An alternative is to imbed the ends in another material.... But this is
not easily
done in the wet state...

Good luck.

Shreefal Mehta

Bone and Ultrasound Lab.
Dept. of Radiology
UT Southwestern Medical Center
Dallas, TX 75235



Kevin:

Try to get in touch with the people in Bioengineering Unit, Universiy
of Strathclyde, Scotland as well as people at Human Performance
Laboratory, University of Calgary. In Strathclyde search for names
such as Evans, Paul, Barbanel, Kenedi and Nicol.

I hope this is of help to you.

With kind regards,

Ricardo Torres-Moreno, Ph.D., Bioengineering
Assistant Professor, School of Physical and
Occupational Therapy, McGill University
3630 Drummond Street, Montreal, Quebec, CANADA H3G 1Y5

E-Mail : RICARDO@PHYSOCC.LAN.MCGILL.CA
Phone : (514) 398-4521
Fax : (514) 398-8193



Kevin,

I am also planning to perform some testing on ligaments. I thought about
embedding the ends in epoxy (Epo Kwick, distributed by Buehler) which
could easily be gripped using standard clamping devices. However, I have no
information about how the temperature produced during polymerization of the
epoxy influences the material properties of the ligament. I would be glad if
you could post answers to that question on biomch-l or forward them to me.

Thanx

chris
__________________________________________________ _________

Christoph Roth

Dept of Mechanical Engineering Office (302) 831-4646
University of Delaware Fax (302) 831-3619
Newark, DE 19716-3140 Home (302) 366-1456

email vollgas@strauss.udel.edu

__________________________________________________ _________



Kevin, colleagues of mine have very successfully utilised the
Cryo-Clamp, a liquid nitrogen cooled clamp with "teeth". The device
clamps tendon specimens in the conventional manner, but is then cooled to
below zero by the liquid nitrogen which then escapes from the clamp as
gas. The tendon in the clamp is then frozen to the shape of the clamp
teeth, allowing an extremely strong holding connection and with which
some extremely strong tendons (eg. horse) have been tensile loaded up to
their ultimate strength. The tendon is frozen only to a point quite close
to the clamp, thereby allowing accurate measurements of strain whilst not
disturbing either the frozen or ambient temperature segments of tendon
matrix. The best person I know on the subject is
d.m.pickles@bristol.ac.uk, who has used the technique very extensively
over a long period of time.

Good luck
Tim Lawes
University of Bristol
Comparative Orthopaedic Sciences
EMail: t.j.lawes@bristol.ac.uk




Dear Kevin,

just a quick note regarding the testing of tendons. Your literature review
should probably have told you to take bone ends as well as the tendon
itself. It is usual then to hold the bone (we usually pot with methyl
methacrylate) and then apply the tension test. If you have any more
specific questions, I will be happy to talk to you, electronically of course!

Kind Regards,

Namal.


Namal Nawana
BioEngineer
Department of Orthopaedics and Trauma
Royal Adelaide Hospital Tel
(08) 303 4723
Fax (08) 232 3065
E-Mail nnawana@mad.adelaide.edu.au



Hi Kevin:

You might want to contact a Ph.D. student at Queen's University who I have
been advising. Her thesis is on mechanical properties of wrist ligaments and
tendons and she devised some cone on cone grips which seemed to work for her.

Her name is Martine Breault (pronounced Bro) and her email address is:

breaultm@qucdn.queensu.ca
================================================== ============
Dr. J. Michael Lee (416) 978-1464 (Voice)
Centre for Biomaterials (416) 978-1462 (FAX)
University of Toronto michael.tigger.mel.dbe.csiro
170 College Street
Toronto, Ontario Australia phone: (61-3) 342-4354
CANADA M5S 1A1 Australia FAX: (61-3) 347-6771
================================================== ============



Hi,

We test equien tendons and use cryo-clamps for both ends. The original
description is in J. Biomech. by Riesmera. We modified it slightly. you
must be careful about the freeze line but in general we get good results
and failure mid-point


Allen Goodship.



Dear Kevin,
I know that Dr Dan Bader from the IRC, Queen Mary and Westfield College,
London, U.K. has completed mechanical tests on tendons and experienced
difficulties with the clamping. Maybe you could contact him for some advice?

Rebecca Eveleigh

University of Bath
Bath
U.K.



Kevin,

Who are you working with? I am working with a couple of students over at
UNMH and we are planning to leave the tendon connected to the bone and
use that as the attachement. For a ligiment study we were giving some
thought to using superglue to attach kevlar tape to the ends.

Marty Weiser
Asst. Prof.
Mech. Engr., UNM



Kevin,

About a year ago we were trying to design a clamping
system to grip quadrupled human hamstring tendons.
We used a system adapted from cryogrips designed
by the biomechanics group at the University of
Vermont. The system uses dry ice placed in a cavity
in the back of the grips to freeze the portion of
clamped tendon. With this system we were able to
achieve failure loads of over 4000 Newtons for
quadrupled hamstring tendons without slippage. However,
you do need to grip about a half inch of material
to achieve adequate clamping. If you are interested
in the design, I can fax you some rough schematics of the
to achieve adequate clamping. If you are interested
in the design, I can fax you some rough schematics of the
grips as well as the materials and methods section
of a paper we are working on describing our tests.
Please email me back you fax number.

Aaron Hecker
Orthopedic Biomechanics Laboratory
Beth Israel Hospital
Boston, MA


Kevin--

I am having a similar problem here. Are you planning to clamp just the
tendon, or the bone plugs on each side? I am having trouble with the
small bone plug size and have been unable to test. We have potted the
bone plugs in a fast curing epoxy resin, and stabilized the bone with a
k-wire inserted at 90 degrees in the bone. However, due to the small
size of the bones, they have pulled away from the k-wire and the epoxy
at very low loads. Perhaps we can work together on this problem.

Thanks.

Erin Herring

-------------------------------------------------------------
Erin J. Herring
email - Erin.Herring@utmb.edu
University of Texas Medical Branch
Phone: 409-772-9073
Fax: 409-772-4253


My limited experience (only live or fresh specimens) has been that best
results are obtained by leaving the natural attachments of the tendon
intact and "clamping" or fixing the connected structure (muscle or bone).
I have also tried suturing to tendon with a loop surounding the entire
tendon as well as several "perpendicular" penetrating stitches so that the
surrounding loop draws snug against the others. This works well when a
piece of the bone is attached as a final "anchor".

Larry Abraham, EdD
Kinesiology & Health Education
The University of Texas at Austin
Austin, TX 78712 USA
(512)471-1273 FAX (512)471-8914
Home: 713-332-6750