A Comparison of Two Total Hip Replacements: Hip Resurfacing System Versus Mallory-Head/Exeter
Condition: Osteoarthrosis
MeSH terms: Osteoarthritis
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of this study is to compare two total hip replacement systems: Hip Resurfacing
      System (ReCap) versus Mallory-Head/Exeter.
    

Detailed description: 
      In Denmark approximately 7000 primary hip replacements are implanted yearly, and the
      incidence is rising with the increasingly aging population. For older patients, the incidence
      of later revisions of hip implantation is low. Unfortunately, this is not true for younger
      patients. Approximately 20% of patients under 55 years of age at the time of surgery must
      have the hip implant renewed within 10 years.

      This is primarily because of the wear generated by polyethylene debris. The polyethylene is
      associated with osteolysis in the proximity of the prosthesis leading to failure of the
      prosthesis.

      This unsatisfactory result has led to the development of an alternative hip prosthesis
      especially to benefit younger and physically active people. The new prosthesis should produce
      less inflammatory debris and less osteolysis induced failure.

      To avoid the polyethylene particles, a new type of prosthesis has been made articulating
      metal on metal. The Hip Resurfacing System consists of an alloy of chrome - cobalt -
      molybdenum. Another point of interest for this prosthesis is also the size of the
      articulating surfaces which are bigger than usual. This will theoretically participate in the
      generation of metal ions.

      Study objectives:

        -  This randomised prospective study will investigate the emission of Co-, Cr- and Mb-ions
           from Hip Resurfacing System and Mallory-Head/Exeter implants, respectively. The emission
           is measured as the ion concentration in the urine and is correlated to the inflammatory
           response in fasting plasma before and after the operation.

        -  To assess the walking pattern postoperatively using a 3D gait analysis, Vicon Polygon.

        -  To assess the postoperative recovery using the Harris hip score and visual analogue
           scale.

        -  The migration of acetabular components will be evaluated by RSA, performing
           radiostereometric analyses at the Orthopaedic Center, Aarhus University Hospital. The
           follow-up RSA will be scheduled for week 1, as well as 3 months, 12 months, 24 months,
           and 5 years after surgery. Bone mineral density around the implanted femoral component
           will be examined by DEXA scan at week 1, as well as 1 year and 2 years after surgery.
    

Intervention name(s): ReCap, Hip resurfacing system, Biomet
Intervention type(s): Device
Intervention description(s): ReCap total hip arthroplasty inserted according to manufactures manual.
Intervention MeSH terms: Cimetidine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Osteoarthrosis; RSA; DEXA; Hip arthroplasty; Metal ion; Inflammatory response; Gait analysis