The primary objectives of the study is to compare gait kinematics and the return to normalization of gait in patients that have undergone a Total Hip Arthroplasty (THA) via the direct anterior approach versus the posterior approach. Gait kinematics will be measured using the IDEEA LifeGait device from Minisun (Fresno, CA).

This is a prospective study of two different surgical approaches to THA, direct anterior vs posterior approach in approximately 64 patients that meet the standard criteria for the implantation of primary total hip replacement utilizing the Medacta implants and have elected to undergo THA.

Inclusion Criteria:

• Patients fulfilling the standard criteria for the implantation of primary total hip arthroplasty
• Those presenting with primary or secondary osteoarthritis
• Those presenting with disease that meets the indications for use for Medacta USA implants defined by this study (on-label use)

Exclusion Criteria:

• Pregnant women or women who plan to conceive within the year following surgery
• Inflammatory arthritic condition
• Those whose prospects for a recovery to independent mobility would be compromised by known coexistent, medical problems
• Those already treated with a failed Total Hip Arthroplasty (THA)
• Muscle contracture around the hip joint
• Individuals who have undergone organ transplant
• Those with a known co-existent medical condition where death is anticipated within five years due to the pre-existing medical condition.
• Those with one or more medical conditions identified as a contraindication defined by the labeling on any Medacta implants used in this study
• Individuals who have had a THA on the contra-lateral side within the 6 months.
• Individuals who have undergone a THR on the contra-lateral side and whose outcome is considered unsatisfactory or not good
• Individuals requiring bilateral hip replacement
• Individuals whose body mass index (BMI; kg/m2) >40
• Individuals with active or suspected infection or sepsis
• Individuals with chronic renal failure as defined by the need for dialysis
• Patients with severe forms of developmental dysplasia of the hip (DDH): Crowe types II, III, IV
• History of drug and/or substance abuse