Computer Navigation vs Conventional Technique in Knee Arthroplasty
Condition: Knee Osteoarthritis; Rheumatoid Arthritis
MeSH terms: Osteoarthritis; Osteoarthritis, Knee
Study type: Interventional

Summary: 
      Project summary:

      Background: Computer navigation in knee replacement surgery is increasingly being used around
      the world, but the documentation of its usefulness is lacking. In order to critically
      evaluate this new surgical method, we want to perform a prospective, randomised clinical
      trial.

      Goal: We evaluate the need for these highly advanced techniques in knee replacement surgery,
      and the cost-effectiveness. Long term outcome for the patients will be predicted by using the
      radiostereometric analysis (RSA). Also, data from the Norwegian arthroplasty register will
      indicate any difference in long term survival of the implant. If there are any differences in
      the functional outcome or complication rate, between the two groups, this will be detected in
      this trial.

      Method: Patients age 50 through 85 years old, with gonarthritis, in need of knee replacement,
      are included in the trial. Radiostereometric analysis (RSA), CT-scans, X-rays, clinical
      evaluation score systems and laboratory measures are used in the evaluation process. A
      cost-effective analysis is performed based on data from Norwegian life tables, data from
      SINTEF and from the Norwegian arthroplasty register. Data from the Norwegian arthroplasty
      register will be statistically analysed separately for all knee replacements done with
      computer navigation in Norway in the last 5 years. Four Norwegian hospitals will collaborate
      in this trial (Haukeland university hospital, Haugesund hospital, Haugesund sanitetsforenings
      hospital for rheumatic diseases and Lovisenberg diakonale hospital) and patients are
      recruited from all four hospitals.

      Scientific impact/challenges: This trial will probably have great impact since good evidence
      supporting the use of computer navigation in knee surgery is lacking. It is important for the
      patient to be confident that he/she receives the best treatment, and it is important for the
      health care providers and funding authorities to have clear evidence when choosing between
      two different treatment techniques, in order for the patient to benefit.
    

Detailed description: 
      Protocol

        1. Introduction: We will perform a prospective, randomized, clinically controlled RSA trial
           comparing:

             1. Profix cemented bicompartmental knee prosthesis implanted with conventional
                intramedullary instruments vs

             2. Profix cemented bicompartmental knee prosthesis implanted with the use of computer
                navigation (from Brainlab)

           The trial will take place at the orthopaedic departments in four hospitals: Haukeland
           university hospital, Haugesund hospital, Haugesund sanitetsforening rheumatism hospital
           and Lovisenberg diakonale hospital.The aim is to compare the technical results (implant
           positioning and stability) for the Profix knee prosthesis, the perioperative morbidity
           and the clinical and functional results comparing the two strategies. We will also
           evaluate the health economical aspect through a cost-effectiveness analysis. To complete
           the project we will analyze data from the Norwegian arthroplasty register with respect
           to the two different strategies. A doctoral fellowship is part of the project.

        2. Background:

           In arthroplastic surgery, scientific evidence is often lacking. Haukeland university
           hospital in Bergen and the Norwegian arthroplasty register are closely tied, and it is
           natural for us to critically evaluate the usefulness and evidence of new implants and
           instrumentation. Computer assisted surgery is well documented in neurosurgery, but there
           have been a few trials in knee replacement surgery suggesting its usefulness. Some of
           these trials show a better alignment and positioning of the implants (1,10,12). In
           addition, retrospective trials have shown that the alignment is predictive of implant
           survival i.e. good alignment gives a better implant survival. (7,8,9) Indirectly that
           may indicate computer navigation is superior in regard to implant survival. Further one
           might assume that a better alignment gives a better functional outcome, and this new
           surgical technique may be less invasive, thus leading to a faster recovery. These
           questions still remain unanswered.

        3. Challenges:

           To date there are no long term studies confirming a definite association between
           computer navigation and better long term results for knee replacements. No trials have
           thoroughly investigated the possible change in functional outcome and morbidity after
           the introduction of computer navigation.

        4. Objectives:

      We seek to find the best treatment for the osteoarthritic patients in need of a knee
      replacement.

        1. In this trial we investigate whether there is a definite correlation between computer
           navigated knee replacements and a better long term survival of the implants.
           Radiostereometric analysis (RSA) will reveal micromotion of the implants and from other
           trials we know this can predict the long term survival of the implants (19,20).

        2. Some trials have reported a higher perioperative morbidity for patients treated
           conventionally, as opposed to those treated with the assistance of computer navigation
           (1,11). Intramedullary rods may increase bleeding, and may give a higher frequency of
           postoperative delirium from microemboli and metabolic disturbances (16). On the other
           hand, the computer navigation is often more time consuming, and can lead to a higher
           risk of infection. The fixation of pin-fixators in femur and tibia for the reflection
           beads might weaken the bone and induce a fracture risk zone. We see that both positive
           and negative aspects of the computer navigation technique will be revealed in this
           trial.

        3. The computer navigation software, hardware and surgical instruments add costs to the
           knee replacement procedure. Hence, it is important to evaluate the benefit as compared
           to the costs. We will analyze this using registry data and a Markov decision analysis.

        4. The Norwegian arthroplasty register has data from all Norwegian hospitals. These data
           will be analyzed and published with regard to computer navigated knee replacement.

      5) Method: We will randomize Profix cemented bicompartmental total knee implanted
      conventionally vs the same prosthesis implanted with the assistance of computer navigation.
      Profix is the standard implant in Helse Vest and it has good 5-year implant survival data in
      our Norwegian arthroplasty register (15).Tantalum markers will be injected into the bone and
      the implant for radiostereometric analysis (RSA). The radiographic technique is somewhat
      challenging and we have recruited specially trained and educated radiographers to obtain
      these images.The images allow us to localize every marker in a three dimensional coordinate
      system. Mathematic models will then calculate differences in position from one image to
      another. Micromotion down to 0,1mm and 0,2 degrees will be detected. Micromotions within the
      first two years correlate with long term implant survival. The radiation dose is low (10-20%
      of a regular x-ray of the knee). The image processing and the calculations are time consuming
      and expensive. Special software is needed and we therefore collaborate with Kompetansesenter
      for ortopediske implantater by Norges teknisk-naturvitenskapelige universitet (NTNU).

      Prior to the inclusion of patients, every surgeon has performed more than 10 knee
      replacements with computer assistance. All surgeons are skilled and have performed more than
      100 knee replacements with the conventional technique. A pilot study with 12 patients (6 in
      each group) will be performed. A total of 200 patients (100 in each group) will be included
      in the trial.

      Only 60 patients will be included in the RSA part of the trial. The precision of the RSA will
      be evaluated by double investigations at a 1-year follow-up. The patient receives two images
      separated by a short period of time. The patient is first radiographed, then he/she takes a
      walk in the investigation room, and is then radiographed again. Micromotion between these two
      images is not real, so then we know the precision of our method. The limits for significant
      differences are calculated as 99% confidence intervals of absolute differences for the double
      investigation. The upper limits for "mean error of rigid body fitting" and "condition number"
      are set to 0,35mm and 130. These parameters describe the stability of the marker and the
      spreading, and expresses the precision of the software. At least 20 patients are needed in
      each group, but the technical demanding procedure has a drop-out risk, leading us to include
      30 patients in each group (23).

      We aim to reveal a difference of 0,5 degrees in the two groups with alignment in the frontal
      plane as measured on the CT-scan. Earlier research in this field indicates a greater
      variation in the conventional group (standard deviation=1,3) than in the computer navigated
      group (standard deviation=0,9) (10). With 80% statistical power and a significance level of
      0.05, a power calculation suggests 79 patients in each group. Further, to be able to detect a
      difference of 10 units in our functional score (KOOS)(13) with a common standard deviation of
      20 (14), our power calculations suggested 94 patients in each group to reach a power of 80%
      at a significance level of 0,05. From these calculations we chose a study design with 100
      patients in each group, assuming there will be some drop-outs. The study is recommended by
      the Regional ethics committee, Personvernombudet for forskning (Norsk samfunnsvitenskapelig
      datatjeneste) and Statens strålevern.

      6) Main activities and milestones: Cost-effectiveness analysis 2010 Inclusion and surgery,
      2010 Analyzing CT scans and functional results, spring and summer 2012 Publication of 3
      months follow-up, fall 2012 Analyzing RSA results 2012/2013 Publication of RSA results
      2012/2013 Register analysis, 2010/2012

      7)Scientific impact: There are many new and expensive instrumentations and implants on the
      market today. In order for Norwegian hospitals to be able to offer a high international
      standard of treatment, we need to evaluate carefully before choices are made. To date,
      computer navigation in knee replacement surgery is not well documented to be recommended as a
      standard procedure at all Norwegian hospitals. Earlier studies are lacking in that they have
      not reported an impact on long term implant survival. This study is unique by using RSA to
      predict long term outcome. It is also large enough to evaluate functional results and
      morbidity. In addition, the register analysis will give us information that has not been
      published. It is important for the patient to be confident that he/she receives the best
      treatment available, and it is important for the health care providers and funding
      authorities to receive clear and accurate information when choosing between two different
      treatments, in order to gain the most benefit.

      8)Dissemination of project results: We will publish our results in high impact international
      medical journals to disseminate the results to colleagues around the world. Lectures and
      presentations in national and international congresses is a natural way to publish the
      results. An investigator education programme, PhD, is incorporated in the project, which
      includes presentations and posters in national and international congresses. The project will
      be registered in an international trial register, according to demands by many journals
      before publishing.
    

Intervention name(s): Computer navigated knee replacement; Conventional knee replacement
Intervention type(s): Procedure; Procedure
Intervention description(s): Total knee replacement performed with the use of navigation system from Brainlab with the Profix total knee implant.; Conventional total knee replacement performed in a traditional way with the use of intramedullary rods, with the Profix implant.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment