Evaluation of Metal-on-conventional-polyethylene vs Ceramic-on-ceramic Articulating Surfaces in Total Hip Arthroplasty

• Articulation wear at 7 years[ Time Frame: At 7 years after surgery ]
  Articulation wear as measured with radiostereometry, mm/year
• Articulation wear at 15 years[ Time Frame: 15 years after surgery ]
  Articulation wear as measured with radiostereometry, mm/year
• Implant fixation at 7 years[ Time Frame: 7 years after surgery ]
  Stem and cup translation (mm/year) and rotation (degrees/year) measured with radiostereometry
• Implant fixation at 15 years[ Time Frame: At 15 years after surgery ]
  Stem and cup translation (mm/year) and rotation (degrees/year) measured with radiostereometry
• Clinical function at 7 years[ Time Frame: 7 years after surgery ]
  Harris Hip Score (0-100)
• Clinical function at 15 years[ Time Frame: 15 years after surgery ]
  Harris Hip Score (0-100)

Polyethylene wear debris from metal-on-polyethylene articulations are one of the main causes of periprosthetic bone loss and non-infectious loosening in total hip arthroplasty. Ceramic articulations have a very low wear rate when measured in the laboratory and the investigator's hypothesis is that hip arthroplasty with an all ceramic articulation will have less osteolysis and wear in addition to equally good fixation and clinical outcome compared to the same hip arthroplasty design with a metal-on-polyethylene joint.

• Device: Ceramic-on-ceramic uncemented hip arthroplasty
• Device: Metal-on-polyethylene uncemented total hip arthroplasty

• Active Comparator: Metal-on-conventional polyethylene
  Uncemented hip arthroplasty (ABG-2, Stryker, Mahwah NJ, US) with a CoCr prosthetic femoral head and an acetabular liner made of intermedially cross-linked polyethylene polyethylene (Duration, Stryker, Mahwah, NJ, US).
• Experimental: Ceramic-on-ceramic
  Uncemented hip arthroplasty (ABG-2, Stryker, Mahwah NJ, US) with a prosthetic femoral head and an acetabular liner made of alumina ceramic (Biolox Forte, Ceramtec, Plochingen, Germany).