One of the leading causes of hip arthritis is femoro-acetabular impingement which means the hip joint is deformed such that the hip joint jams in the front when the hip is bent all the way forward. This can lead to significant damage to the hip joint and may result in the need for a total hip replacement. However, if detected early, this deformity can be treated surgically by reshaping the hip joint. If the hip joint could be better visualized before surgery, then surgeons would be able to develop less invasive surgical techniques to correct this deformity.

In this study, we are trying to develop a way to help surgeons visualize the hip joint before surgery in order to assist with pre-operative planning. This will be done by comparing the dynamic hip images in patients with femoroacetabular impingement to the hip images of healthy volunteers with no hip problems.

Inclusion Criteria:

• All participants (patients and controls) must be between the ages of 18 and 55, with a BMI less than 35.

The patients must have a probable diagnosis of femoro-acetabular impingement (FAI). Their hip pain must have been ongoing for at least 3 months. The controls must have a normal hip as defined by AP pelvis radiographs.

Exclusion Criteria:

• Participants (patients and controls) will be excluded if they are pregnant, have a knee injury or replacement, or history of childhood hip disease. Patients will be excluded if have they have arthritis, previous fracture or trauma to the hip, previous hip surgery, dysplasia, or avascular necrosis. Controls will be excluded if they have hip pain.