Vasti Control of Patellofemoral Kinematics in Asymptomatic Volunteer

Study Summary

Background: * Patellofemoral pain syndrome is one of the most common knee problems. It is characterized by pain in the front of the knee that is aggravated by deep knee flexion, prolonged sitting, and repetitive movement. The most widely accepted theory regarding the source of this pain is that a force imbalance around the knee puts extra stress on the area, leading to pain. * Researchers are interested in learning more about the muscle groups around the knee to better understand the causes of knee pain. Objectives: \- To obtain more information on how muscles, tendons, and bones work together to cause motion in the knee, both in the normal state and after immobilizing certain muscles around the knee. Eligibility: \- Healthy individuals between the ages of 18 and 55, who have no current or chronic muscle, bone, or joint problems and who have no implants or other problems that would prevent them from receiving a magnetic resonance imaging (MRI) scan. Design: * This protocol will be carried out over two visits, both of which will involve using standard MRI sequences to look at the knee at rest and in motion. * The first part will examine the knee under its natural state, with a standard MRI scan of the knee both at rest and in motion. * The second part will involve temporarily reducing the force producing capabilities of one of the extensor muscles in the knee. To do so, study doctors will inject lidocaine into the muscle, which will temporarily (for approximately 2 hours) block the force producing capacity of this muscle, and then perform the MRI scan.