The proposed study is a double-blinded randomized controlled trial comparing patient specific instruments with solely standardized instruments and pre-operative planning used for the placement of the acetabular cup prosthesis used in total hip arthroplasty.

The investigators will enroll 36 patients who have consented to total hip arthroplasty for treatment of hip pathology. This treatment is a standard of care. Patients will receive standard of care pre- and post-operative care and placement of standard of care implants all of which are commercially available and FDA approved for general use for the clinical indications used in these patients. All patients will receive a pre-operative CT scan for surgical planning and comparison with post-operative CT scan. The difference in intervention between the groups will be the creation and use of patient specific instruments from the pre-operative planning session. These instruments will be used for placement of an indexing peripheral guide wire to direct acetabular preparation and placement of the shell assisting standard surgical instruments. Print-offs from the pre-operative plan will also be used in the treatment group.

The post-operative scan will be performed within two weeks of the surgery for both the treatment and control groups. The investigators will analyze the difference in acetabular shell placement (acetabular version and abduction angle) from the pre-operatively planned CT scan. These differences will be compared between the control and experimental groups.

No further details to report.

Inclusion Criteria:

Subjects to be included in this protocol will be adult males and females of all races and socioeconomic status meeting the following criteria:

• Primary, unilateral direct lateral or posterior THA
• 18 to 85 years old at time of surgery
• Able to get a pre- and post-operative CT scan at the Cleveland Clinic

Exclusion Criteria:

• The following criteria will exclude subjects from this protocol:
• Significant metal in the joint that results in metal artifact on the pre--operative CT scan, thereby compromising the ability to visualize the acetabulum on the pre-operative simulator.
• Pregnancy
• Incarceration
• Condition deemed by physician or medical staff to be non-conducive to patient's ability to complete the study, or a potential risk to the patient's health and well-being.