A Prospective Randomized Trial Using Roentgen Stereophotogrammetric Analysis of the Advance Medial Pivot Knee
Condition: Osteoarthritis, Knee
MeSH terms: Osteoarthritis; Osteoarthritis, Knee
Study type: Interventional

Summary: 
      The purpose of this study is to determine whether this particular knee replacement is better
      than those already on the market. By participation, it will further refine the design of
      future total knee replacements and perhaps increase longevity.
    

Detailed description: 
      Joint arthroplasty is an effective surgical intervention, however prosthetic survivorship is
      finite. New or modified prosthetic components are routinely introduced, partly in an effort
      to improve survivorship. When new technologies emerge for total knee replacement it is not
      always evident that they are an improvement over existing options. This determination
      requires long-term follow-up studies. Conventional studies require a large number of patients
      and approximately 10 years of follow-up. By using RSA to measure micromotion of prostheses
      over time problems can be elucidated with a much smaller sample over a shorter time period.
      RSA involves using tantalum markers (0.5-1.0 mm beads inserted in the bone and prosthesis
      during surgery) to measure motion in subsequent bi-planar x-rays of the joint. The relatively
      new Medial Pivot Knee (ADVANCE Knee) theoretically reproduces the natural kinematics of the
      knee but it is unclear what effect this design may have on the forces applied to the tibial
      component-bone interface. The amount of micromotion of the tibial component is directly
      related to the amount of force exerted on it and inversely related to its fixation. In this
      study we propose to compare in vivo micromotion at the tibial component-bone interface with
      the ADVANCE Medial-Pivot Knee (experimental group) versus a more conventional prosthesis
      (control), the ADVANCE Traditional Knee. Patients (n=60; age 45-80 years old) with primary
      osteoarthritis of the knee and mono-articular disease will be randomized to receive either
      the ADVANCE Traditional or ADVANCE Medial-Pivot Knee using Simplex cement. Eight tantalum
      markers will be placed in both the tibia and femur proximal to the prosthesis and in the
      polyethylene tray of the tibial component. Pre-operatively and at 6, 12 and 24 months all
      patients will complete general health (SF-12) and joint specific questionnaires (Oxford -12
      Item Knee Score), have their body mass index calculated, and have the range of motion,
      alignment, extensor function and ligamentous competency of their index knee recorded. On the
      first weight-bearing day after surgery bi-planar standing x-rays will be taken and used as a
      reference point for tibial component position. At 6, 12 and 24 months post-operatively
      patients will undergo more bi-planar standing x-rays incorporating provocative loading tests.
      Micromotion will be analyzed through serial comparison of digital x-rays by blinded study
      personnel using RSA software. Parametric statistics (unpaired Student's t-test) will be used
      to compare the 2 groups.
    

Intervention name(s): Advance Medial Pivot Knee Arthroplasty
Intervention type(s): Device
Intervention description(s): medial pivot total knee arthroplasty tibial component vs standard posterior stabilized tibial component with post. Medial pivot provides a constrained medial condyle through shape of polyethylene and reduces amount of bone removal on femoral side that would otherwise be removed to accommodate PS post
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: arthroplasty; RSA; micromotion; osteoarthritis