Knee pain is a very common complaint of people in the United States. The Center for Disease Control and Prevention (February 2010) found that lifetime risk of knee osteoarthritis may be nearly one in two, or 46%. Nearly half of Americans may develop arthritis in one knee by age 85.
As a licensed physical therapist, I have found knee pain to be one of the most common diagnoses that I evaluate and treat. Common diagnoses that I see in the knee, are osteoarthritis, patellofemoral syndrome (also categorized as “runner’s knee”), chondromalacia, knee ligament sprains, meniscal injuries, total knee replacements and surgically repaired ligaments.
When I evaluate a patient with knee pathology, one of the major problems and biomechanical issues I see is the deactivation/inhibition of the vastus medialis obliques muscle (VMO). The VMO muscle is one of the components that make up the four muscles of the quadriceps and is found on the medial aspect of the knee.
The VMO muscle is important because it is the main dynamic stabilizer of the patella (knee cap). It controls the tracking of the patella when you bend and straighten your knee, especially in activities like stair climbing, running, jumping, and walking. If the VMO does not activate properly, and/or is weak, the patella may track poorly causing pain under/around the patella. This is common in diagnoses like patellofemoral syndrome or chondromalcia. Improved stability and strength of the VMO will return the knee to ideal biomechanics, decrease pain, and prevent future injury.
There are various ways to strengthen the VMO. In my experience I have found that biofeedback is one of the best ways for patients to strengthen and re-educate the VMO. Biofeedback can be performed by visual, auditory, and tactile cueing. I have had great success with the rehab process of knee injuries using a biofeedback machine that I call the “purple box”. The idea of the biofeedback machine is to re-educate the VMO by reconnecting it to the brain. The biofeedback machine has an attached wire with a sensor at one end. When used on a patient, a sensor is placed on the skin at the site of the VMO. When the patient contracts the VMO, the sensor will pick up conduction of the contracted muscle. A baseline number is then set on the machine. The idea is to have the patient contract the VMO above the set baseline number. With practice, re-education, and strength gains, the patient will see the number on the machine increase, improving the activation and control of the VMO by the patient.
There are many ways to re-train and strengthen the VMO in order to return the knee to ideal biomechanics. The biofeedback machine is one form of treatment that allows patients to have control and understanding of their body through the rehab process. I have had good success with the “purple box” to help patients improve strength, stability, and function of the knee.
If you have any questions or comments, please contact Jaime Herrmann, MPT, CSCS at jaime@jointventurespt.com