Hip replacement is a common surgical procedure performed to relieve the pain and disability. In general, the surgery consists of replacing the diseased or damaged joint surfaces of the hip with metal and plastic components shaped to allow continued motion of the hip. Surgeons may perform this operation in several different ways. The purpose of this study is to compare two different methods of performing total hip replacement. The investigators hypothesize that subjects treated with the anterior approached may show improved function during the early postoperative period, but that no differences in pain or function will be present after the first postoperative year.

In this study, patients that have elected to have hip replacement and consented to participate in the study will be randomized to have his or her hip replaced using one of two surgical techniques. Subjects will be randomized to be implanted using either an anterior or posterior approach. With the anterior approach, the study surgeon will use an incision that is on the front of the hip, and with the posterior approach, the incision will be more on the backside of your hip. The study surgeon has done more than 300 total hip replacements with both of these techniques.

A baseline assessment will be conducted before hip replacement surgery that includes x-rays, functional tasks like getting up from a chair and stepping down a step, and three questionnaires about the hip, the subject's general health, and how well the subject is able to function. Also, subjects will be required to return to the clinic at several time points after surgery for follow-up visits. Follow-up visits will include hip assessments and questionnaires, as well as follow-up hip x-rays. The follow-up visits will be 6 weeks, 3 months, 1 year, 2 years, 5 years, 7 years, and 10 years after hip replacement surgery. These follow-up visits are part of the study surgeon's normal routine for hip replacement patients, and are not extra visits as a part of this study.

Inclusion Criteria:

• Between ages of 18 and 85
• End stage hip joint degeneration
• Has elected to undergo primary total hip arthroplasty

Exclusion Criteria:

• Undergoing revision arthroplasty
• Inflammatory or rheumatoid arthritis
• Patients with confounding medical conditions that are not expected to survive for the duration of follow-up (10 years)
• Body Mass Index greater than 40 kg/m2
• Age < 18 or > than 85
• Previous ipsilateral hip surgery including arthroscopic procedures