Retention of the posterior cruciate ligament versus the posterior stabilized design in total knee arthroplasty: a prospective randomized controlled clinical trial

Prosthetic design for use in the primary knee arthroplasty has evolved into
those designs that preserve the posterior cruciate ligament and those in wich
the ligament is routinely sacrificed (posterior stabilized).
Posterior stabilized implants in wich the ligament is excised may substitute
for this function by an intercondylar tibial prominence that articulates with
the femur in flexion.
In the current practice both designs are used. In patients which a non
functional PCL the posterior stabilised design is used. However, in patients
with a functional PCL the decision which design is chosen depends largely on
the favor and training of the surgeon. A limited amount of studies have been
performed into the difference in outcome of the two designs. These studies are
characterised by a small amount of patients, different outcome measures, poor
randomisation and comparing designs of different manufacturers. Range of motion
was the only common outcome parameter; a meta-analysis showed a difference in
range of motion and reproduction angle favoring posterior stabilized designs
over PCL retention designs one year postoperatively. However, it is uncertain
whether this observation is of clinical relevance2. There have been no studies
performed yet determining if there is a difference between designs in patients*
perceived outcome. Additionally, there is a lack of studies determining the
speed of recovery in both designs as most studies only determine the final
outcome (eg after one year).

To examine whether there is a difference in patients perceived outcome between
a posterior cruciate retaining total knee arthroplasty compared with a
posterior stabilized total knee arthroplasty.

Randomized controlled clinical trial.
Patients that are scheduled for a primary total knee arthroplasty and apply to
the inclusion criteria of the study are informed about the trial. After consent
to participate, patients are randomised in two groups. As two surgeons (R.W.
Brouwer and J.J.A.M. van Raay) will perform the surgical procedure, block
randomisation is used. In total 120 patients will be randomised, 60 patients in
each group (60 patients per surgeon).
Measurements will take place preoperatively, 6 weeks, 3 months, 6 months and 1
year postoperatively.
The study will be double blinded: Clinical examination will be performed by a
blinded independent person and the patient will not be informed about which
design is used during the length of the study.
The study will be executed in the Martini Hospital Groningen. Duration of the
study will be 2 years, starting from August 2007.

60 patients receiving the posterior stabilized total knee arthroplasty,
60 patients receiving the posterior cruciate ligament retaining total knee
arthroplasty

Besides the existing risks after placing a total knee arthroplasty no extra
risks are being expected.
The current follow up moments at the outpatient clinic are being used, and
merely some questionnaires are taken which takes only a few minutes extra per
patient.
Also there is a pre- and postoperative gait-analysis at the department of
physical therapy, where the patient is already training under supervision of a
therapist like in the current protocols, so this is expected to be hardly a
burden to the patient.