A multicentre prospective randomised intervention study to investigate computer assisted total knee arthroplasty (TKA) in severe knees.

Effects of kinematic based navigation systems on accuracy and precision in TKA
have been previously provided by a number of publications (1-6) as well as the
International Multicenter Clinical Study 2002-2005, hereafter named PART1.
PART1 addressed patients suffering from knee arthritis without severe
deformities such as axis deviation or bony inconsistencies. These patients
provide the majority of TKA-patients and may profit from use of kinematic based
navigation systems with a reduced risk of component misalignment.
However, a large number of patients requiring TKA are subject of anatomical
deformities, such as gross axis misalignment or bone defects after trauma or
previous surgeries. These patients represent a group with less success of TKA
compared to the non-deformity patients. In general, surgeons recognize such
deformities as highly difficult. Additionally, some deformities, for example
the bowed femur, represent cases, where the classic intramedullary alignment
rod and jigs cannot be used properly.
These patients may profit even more from new technologies of three-dimensional
axis alignment, such as kinematic navigation tools. Consequently, the role of
severe knee deformity on TKA-outcome with and without navigation tools should
be addressed.
Up to today there are no published studies regarding this matter. This may be
due to the fact that severe knee deformities represent a relatively
inhomogeneous population. Thus, single centre studies will lack substantial
patient numbers needed for statistical power.
To overcome these problems, a multicentre study with a jointly used
randomization list is proposed.
The Stryker Knee Navigation System used in this study is a non-imaged based
navigation system developed by Stryker Leibinger with Software 3.1 or higher.


1.CHAUHAN, S.K.; SCOTT, R.G.; BREIDAHL, W.; and BEAVER, R.J.: Computer-assisted
knee arthroplasty versus a conventional jig-based technique. A randomised,
prospective trial. J Bone Joint Surg Br, 86: 372-7, 2004.
2.HEISEL, C.; SILVA, M.; DELA ROSA, M.A.; and SCHMALZRIED, T.P.: Short-term in
vivo wear of cross-linked polyethylene. J Bone Joint Surg Am, 86-A: 748-51,
2004.
3.HSU, H.P.; GARG, A.; WALKER, P.S.; SPECTOR, M.; and EWALD, F.C.: Effect of
knee component alignment on tibial load distribution with clinical
correlation. Clin Orthop Relat Res, 135-44, 1989.
4.ISO 14155 PART I AND II: Clinical Investigation of medical devices for human
subjects- Part 1and 2, first edition 2003-02-15. 2003.
5.SPARMANN, M.; WOLKE, B.; CZUPALLA, H.; BANZER, D.; and ZINK, A.: Positioning
of total knee arthroplasty with and without navigation support. A prospective,
randomised study. J Bone Joint Surg Br, 85: 830-5, 2003.
6.STOCKL, B.; NOGLER, M.; ROSIEK, R.; FISCHER, M.; KRISMER, M.; and KESSLER,
O.: Navigation improves accuracy of rotational alignment in total knee
arthroplasty. Clin Orthop Relat Res, 180-6, 2004.

The aim of this international multicentre clinical study is to compare the
clinical, radiographic and CT scan results, obtained in patients undergoing a
computer assisted TKR procedure with patients undergoing a TKR procedure using
state of the art alignment technique but without a computer based system.
The Stryker Knee Navigation System used in this study is a non-imaged based
navigation system developed by Stryker Leibinger with Software 3.1 or higher.

This is a prospective, comparative, single blind, randomised international
multicentre clinical study. A maximum of 80 patients will be enrolled over a
12 months recruitment period in 3 to 6 centres.
Patients will be appointed randomly by a Computer generated Randomiszation list
(SPSS). The method of randomisation is web-based and described in section 10.1.
The first group will receive a computer assisted TKR, whilst the second group
will receive a conventional TKR. The method of alignment has to be performed
through the classic method. All cases must satisfy the selection criteria and
will be followed for a maximum of 3 months.

Placement of total knee replacement in patients with severe knee deformity.
Operation with or without computer assited navigation.
3 months post-operatively a long leg CT scan is made.

As in any surgical procedure, certain risks are associated with total joint
arthroplasty. These risks include but are not limited to: anaesthetic and
post-anaesthetic reactions (such as hyperaemia), allergic reactions to
prophylactic antibiotics or blood transfusions, damage to blood vessels or
nerves, trochanteric or femoral fractures during implantation, perforation of
the cortical wall, or death. Post-operatively, a patient may experience
thrombophlebitis, pulmonary embolus, dislocation, pain, limp, component
loosening, osteolysis due to wear debris or the need for additional surgery.
Fracture of the prosthesis is a potential complication.
Pre-clinical, clinical, and mechanical testing of the used implants indicate
that the above mentioned risks should not occur at a rate greater than that for
any other type of total knee arthroplasty reported in the literature.


Operation duration when using computer assisted navigaton results in
anasethesia time which is 10-15 minutes longer.
3 months post-op CT scan of long leg of patient results in additional
radiation.