Cemented Marathon/Corail Versus Pinnacle/Corail

Cemented Marathon/Corail Versus Pinnacle/Corail. Comparison of Polyethylene Wear, Component Migration and Periprosthetic Bone Mineral Density. A Randomised Study of 48 Hips Using Radiostereometry and Dual-energy X-ray Absorptiometry

A randomised, comparative, prospective, single-blinded trial of two hip prosthesis:

1. Marathon cemented all-poly acetabular cup(Depuy, Warsaw, Indiana), Corail uncemented femoral stem(Depuy, Warsaw, Indiana), 32mm Alumina Biolox Forte femoral head(Depuy, Warsaw, Indiana) and
2. Pinnacle/Marathon uncemented cup(Depuy, Warsaw, Indiana), Corail uncemented femoral stem(Depuy, Warsaw, Indiana), 32mm Alumina Biolox Forte femoral head(Depuy, Warsaw, Indiana)

There will be a further in-group randomisation to a Corail femoral stem with or without a collar, creating a number of 4 study-groups in total.

The aims of the study are:

• To compare polyethylene wear and migration of the moderately cross-linked Marathon polyethylene in a cemented version(Marathon) and in an uncemented cup(Pinnacle/Marathon)
• To evaluate micromigration and periacetabular bone mineral density of the 2 cups using radiostereometry(RSA)
• To evaluate the migration patterns and proximal femoral bone density changes around the Corail stems with and without a collar

Inclusion Criteria:

• Age under 70 years with primary or secondary arthritis of the hip, aseptic necrosis of the femoral head, acute hip fracture or sequelae after hip fracture.

Exclusion Criteria:

• Active malignant disease, rheumatoid arthritis or other generalised auto-immune arthritic disease,
• BMI > 35,
• insulin dependent diabetes mellitus, 0 chronic or recurrent infection,
• liver disease,
• Paget's disease,
• dementia or lack of compliance for other reasons,
• uncompensated cardiac or pulmonary disease(ASA class 3 or 4). Prosthesis in the contralateral hip does not exclude the patient, but only one hip in each patient can be included in the study.