Postoperative Function Following Partial and Total Knee Replacement

Patients will be asked for a brief medical history so that we may determine if he/she can
participate in the study. If the patient is going to have partial knee replacement, he/she
will be randomly assigned to receive either a fixed-bearing (Vanguard M, Biomet, Warsaw, IN)
or mobile-bearing (Oxford, Biomet, Warsaw, IN) partial knee replacement. Both implant
systems are FDA approved and Dr. Christensen is equally skilled with both systems. The
fixed-bearing partial knee replacement is made up of a polished metal piece that is cemented
to the femur and a metal piece that is cemented to the tibia. The plastic portion of the
fixed-bearing partial knee replacement is attached to the tibial metal tray and does not
move. The mobile-bearing knee replacement also has a metal pieces cemented to the femur and
tibia, but between the two metal pieces is a small plastic piece that moves as the knee
bends and straightens. Patients will have an equal opportunity of receiving either implant
system.

If the patient is having total knee replacement, the surgery will be the same as if he/she
did not participate in the study, except that we will collect information from the patient
during office visits and will ask the patient to perform the functional tests. If the
participant is one of the healthy volunteers, he/she will not have knee surgery and will
only be asked to perform the functional tests.

Information collected during office visits:

A member of our research team will ask the patient a series of questions about the knee.
Patients will be asked to answer this series of questions a total of 4 times over the course
of 1 year. Also, we will record how well the patient can bend and straighten the knee at
these 4 office visits. We will have patients rate the pain in their knee and ask if they
are satisfied with the surgery. If patients have any complications, those will also be
recorded. Patients will have X-rays taken of your knee at your follow-up visits. This is
the normal routine following knee replacement. The X-rays will be read by the surgeon to
help determine the success of the surgery.

We will also ask patients to perform 3 functional tests at each of these office visits.
These 3 tests will be performed on a raised platform that is approximately 2 inches above
the floor. For the first test, the patient will be asked to stand still with knees straight
for two seconds, and then be asked to stand still with knees bent to 45 degrees for two
seconds. For the second test, the patient will be asked to stand up from a seated position.
For the third test, the patient will be asked to step up onto a four-inch wooden box and
then step back down onto the platform. Prior to testing, the patient will be allowed to
practice each of these tests as many times as necessary until he/she feels comfortable.
During testing, an investigator will help make sure that the patient is able to safely and
properly perform 3 repetitions of each test. We will not ask patients to perform one or
more of the functional tests if they are unable to perform the test without constant use of
their arms for support.

Inclusion Criteria:

- Patients that have elected to undergo either partial or total knee replacement, as
well as a control group of patients free of lower extremity pathology

Exclusion Criteria:

- Sensory, neurological, or general health conditions that alter perception of the
patient’s limb in space

- Vestibular disorders will be excluded in order to protect against falls during
functional testing

- Unable to understand the questions used to obtain the Knee Society Score

- Minors and prisoners will be excluded from the study