To evaluate Implant survival based on removal or intended removal of any component of the Entrada™ Hip System at five years of follow-up.

The purpose of this study is to provide clinical evidence for the safety and effectiveness of Ortho Development® Corporation's Entrada™ Hip System (Figure 1). The Entrada™ Hip System was fully introduced to the US market in July, 2018. The Entrada™ Hip System includes the Entrada™ Hip Stem, an FDA approved (510(K) # K171249) femoral stem coupled with either a cobalt chrome or Biolox® Delta Ceramic femoral head. Additionally, the stem and head are coupled with either the Escalade® or Legend® acetabular shell, both of which utilize highly cross-linked polyethylene liners.

Inclusion Criteria:

1. Scheduled to undergo primary total hip arthroplasty using the Entrada™ Hip 2. System due to at least one of the following indications:

• Osteoarthritis

• Inflammatory arthropathy (Rheumatoid Arthritis, Psoriatic Arthritis, etc.) with sufficient bone stock for standard primary THA implants

• Avascular Necrosis with sufficient bone stock for standard primary THA implants

• Post-traumatic Arthritis

• Secondary arthritis due to congenital hip dysplasia 3. Willing and able to provide written informed consent for participation in the study.

  4. Aged 18 - 80 years. 5. Able (in the Investigators opinion) and willing to comply with all study requirements and complete all study visits

Exclusion Criteria:

The potential participant should be excluded from enrollment if any of the following exist:

1. Body mass index ≥ 40
2. History of other orthopaedic surgery within 6 months prior to the index surgery that, in the investigator's opinion, could affect the recovery of the index THA
3. History of pyogenic arthritis in the surgical hip joint
4. Active or suspected infection in or around the surgical hip joint
5. A neurological disorder that, in the investigator's opinion, could affect lower extremity function and recovery from the index THA
6. The potential participant is incarcerated
7. Prior fusion to the index surgical hip joint
8. Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.

9 . Any other contraindication to THA listed in the Entrada™ Hip Stem Labelling or Instructions for Use.

All orthopaedic patients that are scheduled to undergo primary total hip arthroplasty using the Entrada™ Hip System within 12 weeks will be screened for the following eligibility criteria.