Hip replacements are being performed on an increasingly active population, who are likely to wear their implants out prematurely. New hip replacements have been devised to minimise the risk of failure. DePuy RSA RCT is a randomised controlled trial designed to compare the performance of two established types of hip replacements using Corail and Tri-Lock stems along with Deltamotion acetabular component. The primary objective of the trial is to compare the long term stability of these two devices.To do this, the study will use an advanced 3D Xray technique to detect migration of the components at 3 years. The study will also measure micromotion of Corail, Tri-Lock and Deltamotion components, patient reported outcome measures and change in bone density.This study is being conducted at a single site, at the Nuffield Orthopaedic Centre, Oxford.

Inclusion Criteria:

• Women aged between 18 and 65 years and men aged between 18 and 70 years.

  • Participant is willing and able to give informed consent for participation in the study.
  • Diagnosed with hip osteoarthritis.
  • Able (in the Investigators opinion) and willing to comply with all study requirements.
  • Willing to allow his or her General Practitioner and consultant, if appropriate, to be notified of participation in the study.

Exclusion Criteria:

• Any patients with an inflammatory arthropathy, osteoporosis or deformities of the proximal femur.

  • Patients who have significant co-morbidities that would make follow-up difficult or uncomfortable.
  • Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.