The purpose of this study is to evaluate early fixation and stability of the Tritanium cup. It is expected that the Tritanium® cup will be equal to or better than conventional cementless cups in early fixation/stability and meet the expectations of Japanese surgeons.

Inclusion Criteria:

1. Patient is a candidate for a primary Total Hip Arthroplasty (THA).
2. Patient who has diagnosis of secondary osteoarthritis, avascular necrosis and rheumatoid arthritis.
3. Patient whose age is 20 or over.
4. Patient who signed an Institutional Review Board (IRB)-approved, study specific Informed Patient Consent Form.
5. Patient who is willing and able to comply with postoperative scheduled evaluations.

Exclusion Criteria:

1. Patient who has a bacterial infectious disease or has a high risk of a bacterial infection.
2. Patient who requires revision surgery of a previously implanted total hip arthroplasty.
3. Patient who is morbidly obese, defined as having a Body Mass Index (BMI) > 40.
4. Patient who is or may be pregnant female.
5. Patient who has neuromuscular or neurosensory deficiency, which limits ability to evaluate the safety and efficacy of the device.
6. Patient with diagnosed systemic disease (i.e. Paget's disease, renal osteodystrophy), which limits ability to evaluate the safety and efficacy of the device.
7. Patient who is immunologically suppressed or receiving chronic steroids, which limits ability to evaluate the safety and efficacy of the device.
8. Patients who is judged ineligible with specific reason by primary doctor.

Patient who has diagnosis of secondary osteoarthritis, avascular necrosis and rheumatoid arthritis