A Migration and Bone Density Study Comparing 2 Types of Bone Cement in the OptiPac Bone Cement Mixing System

Inclusion Criteria: * primary or secondary knee osteoarthritis * sufficient bone quality for total knee arthroplasty * age above 70 years * no upper age limit if the patient is capable * informed and written consent * patient can only enter the project with one knee Exclusion Criteria: * neuromuscular or vascular disease in the affected leg * preoperatively not found suitable for a knee arthroplasty * patients with osteoporosis based on former diagnosis or preoperative DEXA-scan * fracture sequelae or previous PTO or previous extensive knee surgery * patients with need of a stem-elongation * patients who cannot refrain from taking NSAID post-operatively * continuous medical treatment with vitamin K antagonists (Warfarin) which is known to reduce the bon emineral density by a factor of 5 * patients with metabolic bone disease * patients with rheumatoid arthritis * postmenopausal women in 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 Univ…