∙ 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.