Neural Correlates of Knee Sensorimotor Control in Patients With Patellofemoral Pain Syndrome

Patellofemoral pain (PFP) is one of the most common reported knee conditions in adolescents and young adults. PFP can affect nearly 30% of young adults and most frequently affect those who participate in athletic activities involving running, jumping, and cutting. Pain during movement also adversely influences patellofemoral joint loading as evidenced by increased frontal and transverse plane hip motion during activities of daily living. While the biomechanical and anatomical components contributing to knee pain have been well established, the underlying neural mechanisms are less understood. For adults with chronic pain (e.g., osteoarthritis), patients often exhibit greater 'pain network (e.g., anterior cingulate cortex, thalamus)' activation during sensory testing relative to healthy controls, possibly due to long term peripheral receptor activation resulting in hypersensitivity. Further, inducing pain (e.g., pressing on a thumbnail) results in similar neural activation of the pain network for those who have chronic pain symptoms.

While these studies have been imperative to the understanding of pain on neural functioning, they are limited to those specific populations (e.g., fibromyalgia, osteoarthritis) and do not adequately replicate the pain experienced during daily activities. Traditional approaches consisting of bracing and physical therapy focused on strengthening the knee extensors have been unsuccessful in reducing pain. Further, interventions consisting of exercise therapy have not been effective for all patients with PFP, and other pain-reduction techniques, such as direct electrical stimulation of the motor cortex, have failed to produce improved motor function or long-lasting pain relief. The researchers of this study hypothesize that this is due to the failure to appropriately challenge the full sensorimotor network involved in processing sensory and cognitive stimuli for motor control. To effectively treat pain and manage this condition, the neural correlates of pain and sensorimotor knee control in those with PFP is needed.

To appropriately assess the pain network for those with PFP, replicating knee and hip motion while neural function is measured is needed. The research team has successfully developed a combined knee and hip extension and flexion task that can be used safely with functional magnetic resonance imaging (fMRI). The researchers hypothesize that those with PFP will display depressed sensorimotor activity and increased pain network activity during the knee and hip flexion and extension task relative to previously collected data.

The study visit will consist of one magnetic resonance imaging (MRI) session using a GE SIGNA™ Premier 3.0 Tesla MR scanner. The MRI portion of the study visit will be completed in 75 minutes or less, and the entire visit will last up to 3 hours.