View Full Version : 3million cycles (3yrs) for wear testing?

Alison Mcconnell
08-08-2000, 05:09 AM
Hi there!

I'm a graduate student working on wear testing of polyethylene for use in
total joint replacements. The traditional length of testing is 3 million
cycles and 1 million cycles is accepted as representing approximately one
year of motion. Schmalzried et al (J Bone & Jt Surg, Vol 80-A, No1, Jan
98, pp54-59) reported an average of 0.9 million cycles per year for each
joint of the lower extremity (111 non-randomized volunteers), but also
report the most active patient as walking 3.5 times the average number of
steps per day.

Is 3 years a "make it or break it" point within the lifespan of a
prosthesis or why is 3 years worth of wear considered to be sufficient for
wear testing of purposes? In addition, is the average what should be
tested, or higher than average? How do we ensure success with implants for
patients who are more active than 'average'?

Thanks in advance for your replies! I'll be sure to post what I receive.

Alison McConnell

Alison McConnell
M.Sc. Candidate
Dept of Mechanical Engineering, Queen's University

Centre for Enhanced Mobility (formerly Clinical Mechanics Group)
Queen's University
Apps Medical Research Centre
Kingston General Hospital
Kingston, Ontario
K7L 2V7

(tel) ++1 613 548-2430
(tel) ++1 613 549-6666 xt 2152 (direct)
(fax) ++1 613 549-2529


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