The VMO Dilemma with Patellofemoral Pain

Patellofemoral pain is a broad term used to describe pain on the front of the knee. The diagnosis by itself gives a vague clinical picture because there are many things can cause pain on the front of the knee. A patellar tracking issue is another term typically used interchangeably with patellofemoral pain, which gives a better idea of what the problem is. This blog post will discuss the cause of patellar tracking issues and the current methods for treating it. 

The Old VMO Dilemma

Once upon a time, the quadriceps were the muscle blamed for patellofemoral pain syndromes. This made sense because the quadriceps blend together to form the patellar tendon, which was a structure where the pain was located. The idea was there was a muscle imbalance between the quadricep muscles, the inside muscle (vastus medialis) was too weak compared to the outer muscle (vastus lateralis), causing the patella to rub against the outside of the patellar groove leading to pain. 

The vastus medialis obliquus (VMO) muscle, specifically, was thought to be the muscle too weak to maintain the patella in the middle of the patellar groove. To target the VMO, terminal knee extensions were used to build isolated strength. However, the use of terminal knee extension exercises for the treatment of patellar tracking issues has generally yielded poor outcomes. There is also debate whether the VMO muscle is actually a separate muscle from the vastus medialis. This lead to a new search to find the cause of patellar tracking issues. 

The Issue Isn’t Always Where the Pain Is

It appears that patellar tracking issues may actually be an issue with hip strength and/or endurance. The gluteals and other small muscles in the hip control the rotation of the femur. A strength or endurance weakness in these muscles will lead to uncontrolled internal rotation of the femur. The problem with uncontrolled internal rotation is it will lead the patella to rub against the outside portion of the patellar groove causing irritation and pain. While the biomechanics of the patellar rubbing against the outside of the patellar groove are the same in the above scenario, the target of rehabilitation is different (quadriceps versus gluteals). Research also supports the emphasis on the hip musculature compared to the quadriceps. While both programs showed some benefit, the rehabilitation program focused on the hips showed superior outcomes. 

Treatment Strategy

The presence of pain can alter movement strategies, therefore, pain should be addressed first with patellar tracking issues. Manual therapy and Graston to the tissues around the patella, the quadriceps, and gluteals can help reduce the pain. It is also important to address the biomechanics of the joints which could be causing compensation. If joints are restricted, they won’t be able to function properly. 

The next step in treating patellar tracking issues is to make sure the muscles involved have adequate strength and endurance for the task at hand. The emphasis should be on the gluteals, but strengthening the quadriceps can also be beneficial. Basic exercises include monster walks, hip abduction holds, and clam shells for glutes. Using squats and lunges to target the quads (along with the rest of the lower extremity) can be incorporated once basic strength is adequate. 

While isolated strength and endurance of various muscles is important, it is vital that these muscles are integrated back into movement. You can have the strongest glutes in the world but if they aren’t integrated into the running motor pattern, they will be of little use. These motor control drills will be activity specific; for example, unilateral weighted lunges or various marching drills could be used for running activities. These types of drills will help engrain the proper movement patterns needed to complete the activity. 

 

Suffering from patellofemoral pain or patellar tracking issues? Schedule a free consultation with us to see how we can help!