Safety and Effectiveness Study of OR3O™ Dual Mobility System in THA

Inclusion Criteria: All subjects: * Subject is a suitable candidate for implanting the OR3O™ Dual Mobility System in primary or revision total hip replacement in the Investigator's judgement. * Subject is skeletally mature in the Investigator's judgement. * Subject is 18 - 80 years old (inclusive). * Subject has any of the following conditions: * Advanced degeneration of the hip joint as a result of degenerative, post-traumatic, or rheumatoid arthritis (RA); * Fracture or avascular necrosis of the femoral head; * Failure of previous hip surgery: joint reconstruction, internal fixation, arthrodesis, hemiarthroplasty, surface replacement arthroplasty, or total hip replacement; * All forms of osteoarthritis (OA); * Patients with hips at risk of dislocation; * Femoral neck fracture or proximal hip joint fracture. * Subject provides written informed consent for study participation using an Independent Ethical Committee (IEC) / Institutional Review Board (IRB) approved consent form before any study procedures are performed, including pre-operative data review and/or collection of data on electronic Case Report Forms (eCRFs). * Subject is willing and able to participate in required follow-up visits and is able to complete study activities. * Subject has all required study pre-operative and operative data available in their medical record for collection if consent is given after their THA surgery. Revision Subjects: * Subject has a REDAPT™ Modular Shell implanted which does not require revision or will receive a REDAPT™ Modular Shell during revision THA. * Subject has a S+N compatible stem which does not require revision or will receive a S+N compatible stem during revision THA. Exclusion Criteria: All subjects: * Subject has conditions that would eliminate or tend to eliminate adequate implant support or prevent the use of an appropriately-sized implant, e.g.: * blood supply limitations; * insufficient quantity or quality of bone support, e.g., osteoporosis, metabolic disorders which may impair bone formation, radioactive bone disease, tumor around hip joint, and osteomalacia; * infections or other conditions which may lead to increased bone resorption. * Subject has dysplasia of hip joint with CROWE Grade III, IV. * Subject has bodily disease(s) that may interfere with THA survival or outcome. * Subject has life expectancy of less than 10 years. * Subject has mental or neurological conditions which impair the subject's ability or willingness to restrict activities that may put the affected limb at risk. * Subject has physical conditions or activities which tend to place extreme loads on implants, e.g., Charcot joints, muscle deficiencies, multiple joint disabilities. * Subject has neuromuscular dysfunctions (paralysis, myolysis and abductor muscle weakness) which will cause unstable hip joint or abnormal gait after surgery. * Subject has an emotional or neurological condition that would pre-empt their ability or willingness to participate in the study. * Subject has an active infection - systemic or at the site of intended surgery. * Subject has a Body Mass Index \> 40.0 kg/m². * Subject has a known allergy to any component of the devices used in the study. * Subject is pregnant or breast feeding. * Subject is entered in another investigational drug, biologic, or device study within 30 days of active study participation. Revision Subjects: * Subject has inadequate implant support with an increased risk of implant failure if support is not achieved, poor bone quality exists, or smaller sized implants are utilized. * Subject needs revision of a fractured ceramic head or liner. * Subject was already enrolled into this study as primary THA case.