This article will focus on the distinct, immediate and in some cases ongoing injuries of the much less understood Articularis Genu muscle.
All of us have patient with them…chronic knees. These people have been everywhere, seen everyone, had everything pretty much done to them, yet for some unexplained reason they still come in complaining of “chronic knees” that someone has told them they’ll just have to live with.
There are an amazing amount of therapies that when performed by skilled therapists, can have great positive effects in a patients quality of life. Then there are those patients in which these techniques simply are missing something. This something is most commonly the Articularis Genu muscle.
This muscle is a very commonly overlooked and forgotten structure that contributes to knee dysfunctions. I also have found it a major component in Osgood-Schlatters complaints. It is affected by valgus and varus positions of the knees
Where is it again…?
This muscle is a separate and distinct muscle from the quadriceps. It has a discrete origin beginning at the distal end of anterior femoral shaft ending at the proximal extension of the joint capsule of the knee. It is a part of the sliding subsystem that exists within the knee.
It attaches on to the supra-patellar bursa or pouch. When contracted it elevates the capsule and the synovial membrane of the knee joint and prevents them from being pinched during extension of the leg. It plays a very important role in maintaining proper gait and erect posture.
Injuries
Below are examples of injuries that can have an effect on the Artiularis genu muscle:
Blows to the lateral or medial aspect of the knee
Plant and twist rotational injuries
Inversion sprains of the ankle
Hamstring strains, leg length changes due to dysfunctional alignment of the pelvis
Lumbar injuries to L2-4
Achilles tendon issues
Repetitive impact activities
MVA’s where the patient braces their feet against the floor during impact
Since this muscle is innervated by branches of the femoral nerve at L2-L4 I would suggest looking to your patients’ that complain of discomfort for injury at this level and see if they also are having dysfunctions in their knees.
It’s when this muscle becomes dysfunctional that it really gets interesting. It’s also when therapists get confused. They’ve been told that what they are doing is supposed to “fix” the knee, yet the patient returns regularly.
What can happen?
When watching your patient during gait, look to see if they have terminal extension with heel strike. Most likely they maintain some flexion at the knee and impact with their foot somewhat externally rotated landing in mid-stance. This situation now has the ability not only to continue the dysfunction of the muscle but also places unnecessary strain and torque on the other structures not only in the knee, but also in the ankle, pelvis and spine.
Pain is usually described as a sharp local pain just above the patella. Many times you may find chronic inflammation in the supra-patellar region accompanied by some hypertonicity in the quadriceps. Patient will complain of pain at night when lying supine with knees fully extended. Many sleep with a pillow under their knees to prevent terminal extension. Hamstring shortening can now set in and next we have pelvic mis-alignments.
At the ankle, the calcaneous, talus, and navicular bones, all connected via the Deltoid ligament are all under strain from the loss of heel strike. As the medial structures are pushed medially, the calcaneous now pronates, pushing its lateral body superiorly up into the distal fibula. The fibula has the potential to not only glide anteriorly and posteriorly, but also superiorly and inferiorly. This contact with the lateral calcaneous, pushes the fibula superiorly jamming the proximal head up into the Tibia.
Due to the dysfunctional gait, there is a rotational dysfunction that is occurring at the knee along with the proximal Tib/Fib joint lack of movement. The menisci are prevented from moving effectively placing additional strain on their posterior and anterior soft tissue attachments.
This is a basic look at what can be a very detailed never-ending pain/tension cycle. You can see why therapists and patients become frustrated and confused. They end up chasing the pain from one structure to the next.
The muscle is “kranky!”
It needs to be decompressed, freed from the overlapping quadriceps and allowed to slide and glide efficiently. When it’s dysfunctional, no sliding or gliding occurs as it maintains a constant contracted state elevating the capsule into a position where it gets pinched with every knees extension. When the capsule is irritated, we will see an increase in fluid production and a decrease in fluid re-absorption. If left over a long period of time, the cartilage suffers and increased ware and tear occurs. The menisci are very rich in mechanoreceptors and provide kinesthetic and proprioceptive information to the CNS allowing you to know how and where to place your leg during active movements. This information now becomes less and we see more potential for re-injury to occur.
Treatment
So what do we do? The goal should be to change the environment in which the tissues are attempting to be functional within. There is usually a negative pressure within the knee. When dysfunction is present, this pressure changes to more of a positive pressure. The goal is to assist in returning the pressure back to a more negative state.
To find the articularis genu, palpate the quadriceps at its distal attachment on to the patella, gently investigate medially, with your index and 3rd finger under vastus medialis, and laterally with thumbs under vastus lateralis. Attempt to pinch or connect your fingers and thumbs together. This is where you will find a tight, tense tissue that has very little side-to-side and superior to inferior movements. This can be quite tender for the patient especially if this muscle has never been touched before.
Once you have discovered the muscle, assess what its mobility is, assessing the side-to-side and superior to inferior movements. We can have the patient be active in this process by having them slowly and slightly flex the knee. Does the tissue change somewhat?
Once you have determined which actions need some attention, have the patient continue to ever so slightly flex and extend their knee while you co-operate with the tissues, encouraging mobility in the areas where it is lacking. Repeat 3-4 times and reassess.
Assess the patients gait once again and reassess their standing posture. If you were specific and precise with your treatment, they should be more comfortable in heel striking and standing with their knees in a more neutral position. Inflammation should start to decrease and in the next few days the fluid production, re-absorption process should return to a more functional state. Now you are free to continue treating the compensatory issues.
Conclusion
Armed with good clinical knowledge of anatomy and an understanding of common lower extremity injuries, manual therapists can successfully manage many chronic knee complaints.
As always, I hope that I have been able to serve you in some way with this information, be it a completely new perspective into your patients, be it some new thoughts about how to approach a treatment or provide you with a review and acknowledgement that what you are doing, as far as I’m concerned, is having an amazingly positive impact in improving the quality of life for your patients.