Overview & Efficacy: No formal studies have examined the effectiveness of biofeedback for this disorder but the technique is used so frequently with such success that it is certainly worth trying when subluxation of the patella does not respond to other conservative interventions and before surgery is done.

This therapy has not been formally rated by a panel but would probably be rated as between possibly and probably efficacious (levels 2 to 3 on a scale of 1 - 5 with 5 being the best).

Why biofeedback would help this problem: The patella (knee cap) needs to move smoothly in a set direction along with the rest of the joint during almost every movement of the knee. Position and motion of the patella is nearly entirely controlled by the vastus lateralis and vastus medialis muscles which run from the patella to attachments in the thigh along the femur. The patella can come off track to one side and ride up onto the rest of the joint (types of subluxation) when there is an imbalance between the pulls exerted by the vastus lateralis and vastus medialis muscles. Patelofemoral pain can result from subluxation of the patella. This imbalance may occur due to an injury which weakens one of the muscles. Muscle tension biofeedback is used to measure the ratio of tensions between the vastus lateralis and medialis muscles in the non-painful leg under various amounts of stress in different positions. The ratios for the good leg are compared to ratios of those recorded in the same positions and stresses for the painful leg. People use the display of the tension patterns to match the signals from the bad knee to those from the good knee. When the patterns of movement are corrected through this process, the pain usually goes away.

Brief summary of evidence supporting the efficacy of biofeedback for subluxation of the patella:

LeVeau and Rogers (1980) found that the vastus medialis could be trained to contract independently of the vastus lateralis using EMG biofeedback. Ingersoll and Knight (1991) found that normal people (thirty college women) could be trained with EMG biofeedback to control the position of the patella sufficiently that "the use of EMG biofeedback training to selectively strengthen the vastus medialis oblique appears to be essential in correcting faulty patellar tracking." Sherman (2004) summarized the data supporting use of this technique and detailed the methodology involved.

Detailed information on biofeedback augmented treatment of subluxation of the patella

A. Citations to the papers summarized in the "brief summary" on subluxation of the patella:

Ingersoll C, Knight K: Patellar location changes following EMG biofeedback or progressive resistive exercises. Medicine and Science in Sports & Exercise 23(10): 122-1127, 1991.

LeVeau B, Rogers C: Selective training of the vastus medialis muscle using EMG biofeedback. Physical Therapy 60(11): 1410-5, 1980.

Sherman R: Pain Assessment and Intervention from a Psychophysiological Perspective. Association for Applied Psychophysiology, Wheat Ridge Colorado, 2004. (Book)