No patients will be recruited at Massachsetts General hospital. IRB approval changed to core center.

The objectives of this study are to evaluate the clinical value of robotic-assisted total hip arthroplasty with respect to acetabular cup implantation, and to document the long-term clinical outcome of patients with Total Hip Arthroplasty (THA). IRB approval will be obtained at every study site to evaluate the basic clinical outcomes and post-operative component placement accuracy of each MAKO® THA patient.

The hypothesis is that robotic preparation of the acetabulum will significantly reduce the variability and inaccuracy in the component alignment parameters that lead to post-operative complications, including implant failure.

Inclusion Criteria:

• Male or female
• 20 to 75 years of age
• Subjects requiring primary total hip replacement
• Contralateral hip should be relatively free from arthritis for comparison purposes, specifically with less than a grade of 2 on the Kellgren-Lawrence Scale.
• Subjects diagnosed with osteoarthritis or traumatic arthritis
• Subjects with avascular necrosis
• Subjects who demonstrate the ability to return for follow-up for the next 10 years

Exclusion Criteria:

• Subjects with difficulty understanding protocol for any reason
• Subjects with a limited life span
• Subjects with inflammatory hip disease, previous joint infection, or those requiring hip revision surgery
• Female subjects who are pregnant, or who plan to get pregnant while enrolled in the study

Adults requiring a total hip arthroplasty procedure.