Patello femoral pain? Thinking weak VMO? Think again…

“Atrophy of all portions of the quadriceps muscles is present in the affected limb of people with unilateral PFP. There wasn’t any atrophy of the quadriceps in individuals with PFP compared to those without pathology. Selective atrophy of the VMO relative to the vastus lateralis wasn’t identified in persons with PFP.”

Can the VMO be selectively activated?

They have a common nerve innervation, so many studies say no. Perhaps altering internal/external orientation of the lower extremity (1) or joint angles (2) may play a role. Of course, it also depends on how you are measuring (3). Intramuscular seems to be most accurate!

In the Link Below, section 4, is a nice, brief review of the literature. Thanks to Daithi Grey for the inspiration to put this up!

1. J Strength Cond Res. 2014 Sep;28(9):2536-45. doi: 10.1519/JSC.0000000000000582.
Range of motion and leg rotation affect electromyography activation levels of the superficial quadriceps muscles during leg extension.Signorile JF1, Lew KM, Stoutenberg M, Pluchino A, Lewis JE, Gao J.

2. Phys Ther Sport. 2013 Feb;14(1):44-9. doi: 10.1016/j.ptsp.2012.02.006. Epub 2012 Jun 26.
Muscle activation of vastus medialis obliquus and vastus lateralis during a dynamic leg press exercise with and without isometric hip adduction. Peng HT1, Kernozek TW, Song CY.

3. J Electromyogr Kinesiol. 2013 Apr;23(2):443-7. doi: 10.1016/j.jelekin.2012.10.003. Epub 2012 Nov 8.
The VMO:VL activation ratio while squatting with hip adduction is influenced by the choice of recording electrode. Wong YM1, Straub RK, Powers CM.

10 Principles of Patellofemoral Rehabilitation – Mike Reinold

“Emphasize the QuadricepsThe next principle of patellofemoral rehabilitation is to strengthen the knee extensor musculature. Some authors have recommended emphasis on enhancing the activation of the VMO in patellofemoral patients based on reports of isolated VMO insufficiency and asynchronous neuromuscular timing between the VMO and VL.While the literature offers conflicted reports on selective recruitment and neuromuscular timing of the vasti musculature, the VMO may have a greater biomechanical effect on medial stabilization of the patella than knee extension due to the angle of pull of the muscle fibers at approximately 50-55 degrees.  Wilk et al(JOSPT 1998) suggest that the VMO should only be emphasized if the angle of insertion of the VMO on the patella is in a position in which it may offer a certain degree of dynamic or active lateral stabilization.  As you can see by the figure, if the fibers are not aligned in a position to assist with patellar stabilization, VMO training will likely not be effective.  This orientation of the muscle fibers will differ from patient to patient and can be visualized.Several interventions and exercise modifications have been advocated to effectively increase the VMO:VL ratio, based mostly on anecdotal observations. These include hip adduction, internal tibial rotation, and patellar taping and bracing. Powers(JOSPT 1998) reports that isolation of VMO activation may not be possible during exercise, stating that several studies have shown that selective VMO function was not found during quadriceps strengthening exercises, exercises incorporating hip adduction, or exercises incorporating internal tibial rotation. Powers also states that although the literature offers varying support for VMO strengthening, successful clinical results have been found while utilizing this treatment approach.My belief is that quadriceps strengthening exercises should be incorporated into patellofemoral rehabilitation programs. Strength deficits of the quadriceps may lead to altered biomechanical properties of the patellofemoral and tibiofemoral joints. Any change in quadriceps force on the patella may modify the resultant force vector produced by the synergistic pull of the quadriceps and patellar tendons, thus altering contact location and pressure distribution of joint forces. Furthermore, the quadriceps musculature serves as a shock absorber during weightbearing and joint compression, any abnormal deviations in quadriceps strength may result in further strain on the patellofemoral and/or tibiofemoral joint.In reality, I believe that quadriceps strengthening is very important for patellofemoral rehabilitation, but many exercises designed to “enhance VMO” strength or activation may actually be disadvantageous to the joint.  Take for example the classic squeezing of the ball during closed kinetic chain exercises such as squatting and leg press.  This creates an IR and adduction moment at the hip that is now known to be detrimental to patellofemoral patients.  I would actually propose that we work on quadriceps strengthening without an adduction component and rather emphasize hip adbuction and external rotation.  This can be performed with the use of a piece of exercise band around the patient’s knees during these exercises. “

Do you kick or scrape the inside of your ankle with the other foot ?

We are moving into the final throws of cross country season now and we are seeing the pathologies creep in and the miles go up. Some of you who have been with us for 3 years  have seen this picture but we realized we did not have a blog post on the problem represented by this photo.  This young runner had these scuff marks on the inside of the right lower leg and ankle after a cross country meet.  So what is going on here and what does it tell you ?

Some runners notice that they repeatedly will scuff in the inside ankle or inner calf with the opposite shoe when running. This can happen on both sides but it is more often present unilaterally than bilaterally. 

This problem, typically, but not always represents one of two things:

1- cross over gait (if you are new to our blog in the SEARCH box type in “cross over” and “cross over gait” and be sure to see our 3 part video on the cross over on our youtube channel found here).

2- negative foot progression angle which may or may not be combined with a degree of internal tibial torsion.  Said easier, the runner is “in-toed” or “pigeon toed” but if you have been here with us awhile on The Gait Guys we expect a diagnosis of a higher order so use the former terms, please.

Lets discuss both.

1- Cross over.  When the runner is standing on the right leg, right stance phase of gait, the frontal plane is not properly engaged and the pelvis can drift further over the right foot. This drift to the right will drop the pelvis on the left side. This will alter the pendulum movement of the left leg. Since the global pelvis is moving to the right the left swing leg pendulum moves to the right as well and as it swings past the stance leg it strikes a glancing blow to the inside of the right ankle or calf. This is simple biomechanics and physics. To fix this problem, which is clearly inefficient, one has to determine what is causing the right pelvis drift (there are many causes, the most often thought of cause is a weak gluteus medius on the right but if you have been here with us awhile you will know there are other causes) and then fix the drift. Do not assume it is the gluteus medius all the time, for if it is not, and you employ more glute medius exercises you could be ignoring the source and building a deeper compensation pattern.  Fix the problem, not what you see.

2- Negative foot progression angle and/or internal tibial torsion.  In order to fix this you have to know first if you are dealing with a fixed/rigid anatomic tibial or femoral torsion issue which cannot be fixed or if you are dealing with a flexible progression angle issue. Often, “in-toeing” is accompanied with internal tibial torsion, this is because the knee has to progress forward to keep its tracking mechanics clean, if you correct someone’s foot progression back to neutral and they have internal tibial torsion then you have dragged the patellar tracking outside the normal sagittal progression angle, knee pain will ensue. In fact, the foot progression on the ankle is normal, but the tibia or femur are merely torsioned in a manner that drags the foot inwards with the long bone orientation, again, this is driven by a higher order/demand, to normally track the patella sagittally (forward).  However, if this is a pre-puberty individual you have time because the long bone derotation process is still occuring. Give homework to encourage a good foot tripod and work to strengthen the external hip rotators and encourage sagittal knee tracking mechanics. This is a delicate balancing act, but it can be done, but it is a monster of a project for a blog post because each case is different, variable and always changing depending on the client progress. Remember, you can only encourage more appropriate mechanics and hope that the body will embrace some of the change and encourage some of the de-rotation process to occur from the long bone growth plates. 

The “inside scuff”, to identify its solution you have to know the cause. After all, if it was as easy a fix as “stop doing that” no one would be doing it and we would be out of a job.

Shawn and Ivo …… The Gait Guys