The primary objective of this study is to determine whether the Mini Hip (Corin, U.K.) femoral component has a predictable and stable migration pattern (mean migration of the femoral component in three-dimensions,in mm) over a three year period, compared to a conventional cementless stem (Metafix, Corin, U.K.). The secondary objectives of this study are to determine whether the Trinity (Corin, U.K.) acetabular component has a predictable and stable migration pattern over a three year period and to measure the linear wear of femoral head into the ECIMA Highly Cross-linked polyethylene.

Inclusion Criteria:

• Women and men between the ages of 18 and 65 years old.
• Scheduled to receive a hip replacement
• 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/her General Practitioner and consultant, if appropriate, to be notified of participation in the study

Exclusion Criteria:

The participants may not enter the study if ANY of the following apply:

• Inflammatory arthropathy, osteoporosis or deformities of the proximal femur.
• Significant comorbidities 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 participant at risk due to participation in the study, may influence the result of the study, or the participants ability to participate in the study.