The Gracilis: Have you considered it in your medial knee pain patients?

The gracilis is the 3rd, seldom mentioned contributor to the pes anserine when it comes to knee pain. It lives in the medial compartment of the thigh and helps to add stability to the medial stabilizing complex of the knee.

image credit: https://en.wikipedia.org/wiki/File:Slide3rrr.JPG

During an ideal gait cycle, the gracilis tonically contracts throughout stance phase with bursts from terminal swing through initial contact and again from pre swing to initial swing; it is very similar to the adductors in this respect

The gracilis is a superficial muscle on the medial thigh, running from the the pubic symphisis and upper pubic arch to the pes, sandwiched between the sartorius and semitendinosis. The muscle adducts, medially rotates (with hip flexion), laterally rotates, and flexes the hip , and also aids in flexion of the knee. It can be called upon as a thigh flexor (as can the sartorius) when the abs (particularly the external obliques) do not initiate thigh flexion and the TFL, rectus femoris and iliopsoas groups are dysfunctional. Gracilis dysfunction may contribute to medial knee pain when the thigh needs help flexing. We see this particularly on people with excessive mid foot pronation when the foot remains on the ground too long and need some “help” or a “jump start” to initiate thigh flexion.

Think about this “unsung hero” next time you have a recalcitrant medial knee pain patient.

Gupta, Aman & Saraf, Abhinesh & Yadav, Chandrajeet. (2013). ISSN 2347-954X (Print) High-Resolution Ultrasonography in PesAnserinus Bursitis: Case Report and Literature Review. 1. 753-757. 

Gray H:  Anatomy of the Human Body  Lea and Febiger, Phildelphia and New York 1918

 Michaud T: in Foot Orthoses and Other Forms of Conservative Foot Care Williams & Wilkins, 1993 Pp. 50-55

 Michaud T: in Human Locomotion: The Conservative Management of Gait-Related Disorders 2011

Recalcitrant medial knee pain? Have you heard about the "Problematic Pes"...

image source: https://commons.wikimedia.org/wiki/File:Slide2DADE.JPG

Recalcitrant knee pain just below the medial tibial plateau? Worse with sprints, hills and after running a while? It may be the pes anserine insertion(s).

Made up of the tibial insertions, from anterior to posterior, of the sartorius, gracilis and semitendinosis which lie superficial to the distal tibial insertion of the superficial medial collateral ligament. This structure is named from the way it looks, like a goose's foot (anserine pes), rather than its anatomical location. The pes anserine bursa lies below it and between the MCL and hamstring tendons and can be subject to compressive forces if compromised in some way, by injury or pathomechanics

The muscles of the pes anserine arise from three different compartments in the thigh. The sartorius originates from the anterior compartment,  the gracilis from the medial compartment and the semitendinosus, the posterior compartment. Their varied origins, paths, and actions, as these muscles approach their insertion all add stability to the medial aspect of the knee.

During an ideal gait cycle, the sartorius fires from toe off through nearly terminal swing, the semitendinosus from mid swing through nearly loading response, with a brief firing at toe off  and gracilis tonically throughout stance phase with bursts from terminal swing through initial contact and again from pre swing to initial swing.

image source: Tom Michaud, with permission

We remember that the abdominals should initiate thigh flexion with the iliopsoas, rectus femoris, tensor fascia lata and sartorius perpetuating the motion. Sometimes, when the abdominals are insufficient, we will substitute other thigh flexors, often the psoas and/or rectus femoris, but sometimes sartorius, especially in people with excessive midfoot pronation. Think about all of the medial rotation occurring at the knee during excessive midfoot pronation and when overpronation occurs, the extra compensatory external rotation that must occur to try and bring the knee back into the sagittal plane. The sartorius is positioned perfectly for this function, along with the semitendinosus which assists and external rotation and closed chain with the innocent pes anserine bursa directly beneath. This is complemented by the compressive forces of this gracilis firing because of the increased coronal plane motion occurring at the pelvis.

Call it pes anserinus bursitis or pes anserine tendinitis but they both add up to medial knee pain when the thigh needs help flexing.

Look to this troublesome trio the next time you have recalcitrant medial knee pain.

Gupta, Aman & Saraf, Abhinesh & Yadav, Chandrajeet. (2013). ISSN 2347-954X (Print) High-Resolution Ultrasonography in PesAnserinus Bursitis: Case Report and Literature Review. 1. 753-757. 

https://www.anatomy-physiotherapy.com/knee/articles/systems/musculoskeletal/lower-extremity/knee/test-your-knowledge-the-pes-anserinus

 Michaud T: in Foot Orthoses and Other Forms of Conservative Foot Care Williams & Wilkins, 1993 Pp. 50-55

 Michaud T: in Human Locomotion: The Conservative Management of Gait-Related Disorders 2011