This is a single-centre, randomised, prospective clinical follow-up study to evaluate clinical outcome and gait analysis after total hip arthroplasty using the standard postero-lateral approach or the minimally invasive anterior approach.

Inclusion Criteria:

• Males and females aged 18-75 years at time of surgery.
• Those presenting with primary or secondary osteoarthritis and/or rheumatoid arthritis of the hip.
• Those deemed capable of giving informed consent, understanding the aims of the study and expressing willingness to comply with the post-operative review programme.
• Patients who signed the study consent form prior to surgery.

Exclusion Criteria:

• Pregnant women or women who plan to conceive in the future.
• Those whose prospects for a recovery to independent mobility would be compromised by known coexistent, medical problems.
• Those already treated by with a Total Hip Replacement (THR) (i.e. requiring a revision hip replacement).
• Those with co-existent ipsilateral knee disease or back problems
• Muscle contracture around the hip joint
• Individuals who have undergone organ transplant.
• Those with a known co-existent medical condition where death is anticipated within five years due to the pre-existing medical condition.
• Individuals who have had a THR on the contra-lateral side within the 6 months.
• Individuals who have undergone a THR on the contralateral side and whose outcome is considered unsatisfactory or not good. An unsatisfactory or poor result is defined as achieving a total UCLA score (including activity) < 16 points.
• Individuals requiring bilateral hip replacement.
• Individuals whose body mass index (BMI; kg/m2) >35.
• Individuals with active or suspected infection or sepsis.
• Individuals with renal failure and/or renal insufficiency.
• Patients with severe forms of developmental dysplasia of the hip (DDH): Crowe types II, III, IV.