Polyethylene Wear Study on the Triathlon Total Knee Prosthesis_A Comparison of a Highly-crosslinked and a Crosslinked PE in-vivo

At the orthopedic department of 't Lange Land Ziekenhuis, research is being
performed on the functionality of knee prosthesis.
During this research the differences of 2 types of knee layers will be reviewed.
One type, N2Vac is regular used material with excellent features on wear
prevention.
The second type is X3, is the latest, new generation layer on which excellent
features are being assigned.
The objective of this study is to compare the fixation and wear of the 2 types
of layers. The best way to measure this is the RSA x-ray. This is an x-ray on
which the fixation into the bone can be measured in detail. During the
operation tantalum beads will be inserted into the bone around the prosthesis,
to being able to perform the RSA X-rays.

1. The primary objective is the assessment of the in vivo wear of the two
randomized polyethylene inlay types N2Vac and X3 by means of Roentgen
Stereophotogrammetry. It is expected that the X3 group will show significantly
less wear after 5 years compared to the conventional N2Vac polyethylene group.
2. The secondary objective is the assessment of prosthetic migration results
after two years of the Triathlon CS Peri-Apatite coated tibial and femoral
components by means of Roentgen Stereophotogrammetry. It is expected that due
to the superior wear qualities of X3 polyethylene this group will show
significantly less migration of the prosthesis* components after two-years
compared to the components in the N2Vac group.
3. The third objective will be the prediction of the long-term survival of the
Triathlon CS Peri-Apatite coated tibial and femoral components based on the
two-year migration patterns combined with clinical factors and radiographic
aspects. In order to identify other clinical parameters besides wear
influencing the fixation of the prosthesis components, clinical scores and
radiographic aspects will be correlated with the RSA outcome. Subsequently, a
long-term prediction can be for the Triathlon CS Peri-Apatite coated tibial and
femoral components.

Single-Center Randomized Controlled Trial (RCT) to compare conventional UHMWPE
with X3 highly cross-linked polyethylene in a CS fixed bearing total knee
prosthesis.
All Patient recruitment and RSA image acquisitions will take place in: *t Lange
Land Ziekenhuis, Zoetermeer.
The Quality Control of the RSA images and RSA image analysis will be carried
out by the CRO (ClinFact, Leiden, the Netherlands).

Post operative the patients will be seen at 6 weeks, 3 months, 6 months, 1
year, 2 year and 5 years.
The oxford knee score, SF-36, EQ-5D en lower extremity activity will be
assessed.

RSA analysis will be done at:

PTD,6 weeks, 3 months, 6 months, 1 year, 2 year and 5 years.

All patients will have a total knee replacement operation during which the
prothesis and study layer or the control knee layer will be implanted.

The risks for the patients are the standard risks of a total knee replacement
surgery. A surgery which the patient also will have if he/she does not
participate in the study.
(eg. Infection, vascular disorders, thrombus, bronchopulmonary disorders)
At each visit one extra X-ray will be taken of which the radiation exposure
will be largely beneath the allowed exposure.
The additional annual radiation dose is negligible if the natural annual
exposure of 2m Svis considered and will do the patient no harm.
(Blake et al. 1996)