The purpose of this scientific study is to compare early migration of hip prostheses in respect to the bone in order to determine whether there is a clinical difference between the two investigated bone cements (which one is best suited for cementation of hip prostheses).

A randomized controlled clinical trial on 50 hybrid hips age above 70 years to the described two surgical procedures will be performed at Aarhus University hospital by two orthopaedic consultants. Randomization in 10 blocks of ten patients distributed with five patients for Palacos Cement and five patients for Hi-Fatigue Cement.

• 25 CPT femoral stems fixed with Hi-Fatigue Bone Cement.
• 25 CPT femoral stems fixed with Palacos Bone Cement.

All patients will be operated by the postero-lateral approach. The post-operative treatment and training will not differ from the standard.

Inclusion Criteria:

• primary hip osteoarthritis
• sufficient bone quality for total hip arthroplasty
• age 71 years and above
• no upper age limit if the patient is capable
• informed and written consent
• patient can only enter the project with one hip

Exclusion Criteria:

• planned bilateral hip surgery
• neuromuscular or vascular disease in the affected leg
• preoperatively not found suitable for a hip arthroplasty
• patients with osteoporosis based on former diagnosis or preoperative DEXA-scan
• fracture sequelae, osteonecrosis or previous extensive hip surgery
• patients who cannot refrain from taking NSAID post-operatively
• continuous medical treatment with vitamin K antagonists (Warfarin) which is known to reduce the bone mass by a factor of 5
• patients with metabolic bone disease
• patients with rheumatoid arthritis
• postmenopausal women in systemic estrogenic hormone substitution
• patients with a continuous need of systemic cortisone treatment
• non-Danish citizenship
• patients who do not comprehend the Danish language (read and speak)
• senile dementia
• alcoholism - defined as men drinking more than 21 units a week and women drinking more than 14 units a week
• drug abuse
• major psychiatric disease
• metastatic cancer disease and treatment with radiation therapy or chemotherapy
• severe systemic disease (e.g. hemi paresis and Parkinson disease)
• systemic hip and spine disease
• employee at the orthopaedic department, Aarhus University Hospital
• ongoing case regarding industrial injury insurance of the knee
• patients with poor dental status (risk of infection)