The plan is enroll 44 subjects (22 in the standard surgery group and 22 in the experimental surgical group) into this randomized clinical trial. All subjects will have the standard of care indications for THA and will give informed consent for both the surgery and participation in this study. Enrollment will occur as part of the routine office evaluation and will be obtained by the treating surgeon or by the research assistant. Four surgeons (Wael Barsoum, Trevor Murray, Carlos Higuera, and Michael Bloomfield) with surgical experience in total hip arthroplasty will perform the procedures in this study. All subjects within each surgeon's practice who qualify for participation in this study will be approached. Subjects will be enrolled at least 10 days prior to the date of surgery. Ten days is the minimum time necessary to obtain a pre-operative CT scan for surgical planning and to manufacture the surrogate bone model. Patients who are not approached during regular office visits will be contacted by phone and if they are interested, they will be scheduled to arrive to the radiology department to sign the informed consent and receive the preoperative CT scan. Subjects will be randomized into either the experimental or control group at the time of consent by the study coordinator. Subjects in the experimental group will have their pre-operative planning done using the 3D surgical simulator and surrogate bone model will be available for the surgeon during surgery. Subjects in the control group will have their pre-operative planning done using plain film x-ray and two-dimensional (2D) templates.

Eligible subjects for inclusion in the study will be able to receive a pelvic CT scan at the Cleveland Clinic. Additionally, we will obtain standard of care pre- and post-operative x-rays (AP view). For subjects randomized into the experimental group, their CT scan DICOM images will be uploaded into the Cleveland Clinic developed surgical simulator specifically designed for THA at least 10 days prior to surgery. For each experimental subject, the Cleveland Clinic pre-operative planning software will be used to define the optimal size and location of the acetabular components (acetabular shell, and the ultra-high molecular weight polyethylene bearing - UHMWPE). The treating surgeon will virtually place the implant in the simulator software. The specification for shell placement will vary depending on the subject's individual pathology and pelvic morphology, but is expected to fall within the range of 10-35 degrees of anteversion and 30-50 degrees of abduction.

In the control group, each surgeon will use their standard methods of pre-operative planning using the pre-operative x-rays. To prepare the acetabulum and place the implants on the day of surgery, surgeons will use standard surgical alignment instruments provided by the manufacturer of the implant. For the experimental group, the surgeon will use CT scan and a 3D preoperative planning software to place the implants virtually. The surgeons are provided with a surrogate bone model with a fabricated acetabular implant placed in the same orientation as was planned in the surgical simulator software, and will use standard surgical instruments provided by the manufacturer of the implant.

The images obtained from the post-operative CT scans will be uploaded into the simulator software for 3D reconstruction. The 3D image of the post-operative pelvis with the implants will be superimposed onto the image of the pre-operative pelvis with the virtually placed implants. Using measurement tools within the software we will compare the position of the actual acetabular component placed in the patient with the desired position specified by the plan. The measurements that will be made are for angular orientations in 3D space (anteversion and inclination). Measurements are accurate to within a fraction of a degree.