The aim of this study is to further investigate the clinical and radiological importance of design changes in cementless hip prosthesis. The investigators have earlier evaluated the classical Furlong HAC total hip prosthesis and a first design change Furlong Active. Now a further development, Furlong Evolution, is to be evaluated. This prosthesis, furthermore, comes with and without a collar, and the investigators are going to randomize between the two. The investigators hypothesize that the new design will be easier to implant and will present equal or less migration than the older designs which would imply a favourable outcome in the long term. The investigators further hypothesize that the collar play no major part for the long term migration and bone remodelling.

We will now do a 10 year follow up of the patients including RSA, DXA and PROMS

Inclusion Criteria:

• Primary osteoarthritis of the hip necessitating primary hip replacement
• A femur considered suitable for uncemented fixation of the stem
• Biological age <75 years old at the inclusion time of the study.

Exclusion Criteria:

• Rheumatoid arthritis
• Malignant disease
• Severe osteoporosis
• Earlier fracture or operation in the hip to be operated on
• Peroperative fracture
• Ongoing corticosteroid (oral) or immunosuppressive medication
• Personal disorders (dementia, alcohol or drug abuse etc) suspected of making completion of the trial uncertain.