Knee pain and the the semitendinosis?

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

The semitendinosus hails from the posterior compartment.

During an ideal gait cycle, the semitendinosus from mid swing through nearly loading response, with a brief firing at toe off.

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.

The semitendinosis is the most superficial of the hamstrings and originates between the biceps femoris, with which it shares a common tendinous attchment, which is anterior and slightly lateral and the semimembranosis which is just beneath it and slightly medial. It is fusiform and the muscle body ends about mid thigh, before becoming a long "piano string" and ultimately inserting most inferiorly of the trio, below the gracilis, on the pes anserine.

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.

Dr Ivo Waerlop, one of The Gait Guys

#gait, #gaitanalysis, #gaitdysfunction, #thegaitguys, #pesanserine, #semitendinosis

Imani F, Rahimzadeh P, Abolhasan Gharehdag F, Faiz SH. Sonoanatomic variation of pes anserine bursa. Korean J Pain. 2013;26(3):249-54. 

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

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

The Sartorius: insertional tendinitis and medial knee pain?

We all see folks with medial knee pain, many times women, with the pain located just below the medial tibial plateau. It often results from running, but sometimes with jumping sports like basketball as well. It has been our experience that these people are often diagnosed with an MCL type injury, but when you examine them further, they do not really fit the bill. All the ligaments are stable and there is no tenderness at the joint line. The is often tenderness at the pes anserine, but who is driving the bus here?

image source: https://commons.wikimedia.org/wiki/File:Muscles_and_tendons_of_the_legs_and_feet;_écorch_́figur_Wellcome_V0008276.jpg

The sartorius originates from the anterior compartment of the thigh. During an ideal gait cycle, the sartorius fires from toe off through nearly terminal swing (1)

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 in closed chain. This is why it is often implicated as the culprit in many cases of pes anserine bursitis (or as we like to say “sartorius insertional tendinitis” (2-3)

Some other things you may find interesting is that it is utilized more in crossing or cutting maneuvers while changing directions while running (4). This makes sense, given its anatomical course and origin/insertion. It can often be overlooked in adductor strains. It can also be avulsed during sprints, particularly in adolescents (5) and because of the course of the lateral femoral cutaneus nerve beneath it, can be the cause of meralgia paresthetica (6). It is proprotionally smaller in females (along with the gracilis and short head of the biceps femoris) (7). And during vertical jumping, is considered an internal rotator, along with the semimembranosis, semitendinosis, gracilis, and popliteus (8).

The sartorius is superficial in the anterior thigh, just under the skin, running from the ASIS, coursing lateral to medial and inserting at the pes anserine at its most superior aspect, just overlying the gracilis. Since it is an external rotator, knee flexor and assists in thigh abduction, you can easliy locate it by placing the patient in a "figure 4" position and having them resist as you pull downward on the leg. Be careful if you are needling this muscle because of the subsartorial canal (ie Hunters canal) lying just beneath it in the middle 1/3 of the thigh, from the apex of the femoral triangle to the adductor hiatus in the adductor magnus. It houses the femoral artery and vein, as well as the saphenous nerve and nerve to the vastus medialis.

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

2. Imani F, Rahimzadeh P, Abolhasan Gharehdag F, Faiz SH. Sonoanatomic variation of pes anserine bursa. Korean J Pain. 2013;26(3):249-54. 

3. 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. 

4. Rand MK, Ohtsuki T. EMG analysis of lower limb muscles in humans during quick change in running directions. Gait Posture. 2000 Oct;12(2):169-83.

5. Manning CJ, Singhai S, Marshall P. Synchronised sartorius avulsions in adolescent sprinter. BMJ Case Rep. 2016 Jul 13;2016.

6. Hsu CY, Wu CM, Lin SW, Cheng KL. Anterior superior iliac spine avulsion fracture presenting as meralgia paraesthetica in an adolescent sprinter. J Rehabil Med. 2014 Feb;46(2):188-90. doi: 10.2340/16501977-1247.

7. Behan FP, Maden-Wilkinson TM, Pain MTG, Folland JP. Sex differences in muscle morphology of the knee flexors and knee extensors. PLoS One. 2018 Jan 23;13(1):e0190903.

8. Cleather DJ. An important role of the biarticular hamstrings is to exert internal/external rotation moments on the tibia during vertical jumping. J Theor Biol. 2018 Oct 14;455:101-108

The Gluteus Medius: Its not just for abduction anymore...

It would logically follow that the gluteus medius is important for generating both forward progression and support, especially during single-limb stance suggesting that walking dynamics are influenced by non-sagittal muscles, such as the gluteus medius, even though walking is primarily a sagittal-plane task. After midstance, but before contralateral preswing, support is generated primarily by gluteus maximus, vasti, and posterior gluteus medius/minimus; these muscles are responsible for the first peak seen in the vertical ground-reaction force. The majority of support in midstance was provided by gluteus medius/minimus (NOT the maximus), with gravity assisting significantly as well. The gluteus medius has also been highlighted as an abductor of the pelvis, working in concert with the contralateral quadratus lumborum (2), involved with keeping the pelvis level and abducting the pelvis on the stance leg side, such as when ascending stairs. 

Seemingly, the gluteals appear important for extension of the thigh during gait. One of the most common scenarios appears to be a loss of ankle rocker and resultant weakness of the gluteals (personal observations). Lets look at an example. 

Have you ever sat at the airport and watched people walk? I travel a great deal and often find myself passing the time by observing others gait. It provides clues to a plethora of biomechanical faults in the lower kinetic chain, like a loss of ankle rocker with people who wear flip flops or any other open backed shoes.

What is ankle rocker, anyway? According to Jaqueline Perry (THE Matriarch of Gait Analysis) during normal gait, the stance phase (weight bearing) foot depends on 3 functional rockers (pivots or fulcrums) for forward progression (3).

• heel rocker: at heel strike, the calacaneus acts as the fulcrum as the foot rolls about the heel into plantar flexion of about 10 degrees . The pretibial muscles must contract eccentrically to slowly lower the foot and help, along with forward momentum, pull the tibia forward
• ankle rocker: next, the ankle acts as at fulcrum and the tibia rolls forward due to forwardmomentum, with a maximum excursion of approximately 15 degrees. The gastroc and soleus should eccentrically contract to decelerate the forward progression of the lower leg.
• forefoot rocker: the metatarso-phalangeal joints act at the finalfulcrum in the stance phase of gait. Note that the 1st metatrso-phalangeal joint must dorsiflex65 degrees for normal forward progression, otherwise the individual will usually roll off he inside of the great toe. Tibial progression continues forward and the gastroc/soleus groups concentrically contract to decelerate the rate of forward limb movement. This, along with passive tension in the posterior compartment muscles, forward momentum , and the windlass effect of the plantar fascia result in heel lift.

Now watch someone walking in flip flops or open back shoes. There is no pivot past 90 degrees at the ankle (i.e. the tibia never goes beyond 90 degrees vertical). At this point the heel comes up (premature heel rise) and the motion must occur at the metatarso-phalalgeal joint. The only problem is that this joint usually has a maximum of 65 degrees extension, with 50 degrees needed for "normal" ambulation. Since more is now needed, the body borrows from an adjacent joints, namely the knee (which increases flexion) and the interphalangeal joints (which should be remaining flat and now must claw to “create” more available extension at the middle joint, as the proximal is nearly fully extended, through overactivity of the flexor digitorum longus. The tibialis posterior, flexor hallicus longus, and gastroc soleus groups also contract in an attempt to help stabilize the foot . Overactivity of these groups causes reciprocal inhibition of the long toe extensors and ankle dorsiflexors (tibialis anterior for example), causing the toes to buckle further and a loss of ankle dorsiflexion; in short, diminished ankle rocker function.

So there you have it. Glutes. They are a beautiful thing! Now get out there and improve their function!

1. Presswood L, Cronin J, Keogh J, Whatman C (2008). Gluteus Medius: Applied Anatomy, Dysfunction, Assessment, and Progressive Strengthening. Strength and Conditioning Journal, 30 (5), 41-53

2. J. Porterfield, C. DeRosa (Eds.) Mechanical low back pain. 2nd ed. WB Saunders, Philadelphia; 1991

3. Perry J, Burnfield JM, eds. Gait Analysis: Normal and Pathological Function. Journal of Sports Science & Medicine. 2010;9(2):353.

Pronation as a shock absorber?

We sometimes (or often) think of pronation as a BAD thing. It's actually a pretty good thing... Along with ankle dorsiflexion, knee flexion, hip flexion and drop of the contralateral pelvis

Check out our quick video on all the shock absorbing mechanisms

The EHB....In all its glory...

The extensor hallucis brevis : An overlooked "miracle worker"

The Extensor Hallicus Brevis, or EHB as we fondly call it is an important muscle for descending the distal aspect of the 1st ray complex (1st metatarsal and medial cunieform) as well as extending the 1st metatarsophalangeal joint. It is in part responsible for affixing the medial tripod of the foot to the ground.  Its motion is generally triplanar, with the position being 45 degrees from the saggital (midline) plane and 45 degrees from the frontal (coronal) plane, angled medially, which places it almost parallel with the transverse plane. With pronation, it is believed to favor adduction (1).

It arises from the anterior calcaneus and inserts on the dorsal aspect of the proximal phalynx. It is that quarter dollar sized fleshy protruding, mass on the lateral aspect of the dorsal foot.  The EHB is the upper part of that mass. It is innervated by the lateral portion of one of the terminal branches of the deep peronel nerve (S1, S2), which happens to be the same as the extensor digitorum brevis (EDB), which is why some sources believe it is actually the medial part of that muscle. It appears to fire from loading response to nearly toe off, just like the EDB; another reason it may phylogenetically represent an extension of the same muscle (2-4).

Because the tendon travels behind the axis of rotation of the 1st metatarsal phalangeal joint, in addition to providing extension of the proximal phalynx of the hallux (as seen in the child above), it can also provide a downward moment on the distal 1st metatarsal (when properly coupled to and temporally sequenced with the flexor hallicus brevis and longus), assisting in formation of the foot tripod we have all come to love (the head of the 1st met, the head of the 5th met and the calcaneus).

Why is this so important?

The central axis of a joint (sometimes called the instantaneous axis of motion) is the center of movement of that articulation. It is the location where the motion will occur around, much like the center of a wheel, where the axle attaches. In an articulation, it usually involves one bone moving around another. Lets look at an example with a door hinge.

A hinge is similar to a joint, in that it has parts with is joining together (the door and the jamb), with a “joint” in between, The axis of rotation of the hinge is at the pivot rod. When the door, hinge and jamb are all aligned, it functions smoothly. Now imagine that the hinge was attached to the jamb 1/4” off center. What would happen? The hinge would bind and the door would not operate smoothly.

Now let’s think about the 1st metatarsal phalangeal joint. It exists between the head of the 1st metatarsal and the proximal part of the proximal part of the proximal phalanyx. Normally, because the head of the 1st metatarsal is larger than the heads of the lesser ones, the center of the joint is higher (actually,almost 2X as high; 8mm as opposed to 15mm). We also remember that the 1st metatarsal is usually shorter then the 2nd, meaning during a gait cycle, it bears the brunt of the weight and hits the ground earlier than the head of the 2nd.

The head of the 1st metatarsal should slide (or should we say glide?) posteriorly on the sesamoids during dorsiflexion of the hallux at pre swing (toe off). It is able to do this because of the descent of the head of the 1st metatarsal, which causes a dorsal posterior shift of the axis of rotation of the joint. We remember that the head of the 1st descends through the conjoined efforts of supination and the coordinated efforts of the peroneus longus, extensor hallucis brevis, extensor hallucis longus, dorsal and plantar interossei and flexor hallucis brevis (which nicely moves the sesamoids and keeps the process going smoothly)(1, 5).

Suffice it to say, if things go awry, the axis does not shift, the sesamoids do not move, and the phalanyx crashes into the 1st metatarsal, causing pain and if it continues, a nice spur you can write home about!

Treating and needling this muscle is easy, as it is very accessible on the dorsum of the foot and due to the decreased receptor density, is not too uncomfortable. We like to needle the peroneus longus and short flexors as well, as they all have the function of lowering the head of the 1st ray. Check it out in this quick how to video.

1. Michaud T: Human Locomotion: The Conservative Management of Gait Related DisordersNewton Biomechanics; First Edition 2011

2. https://www.physio-pedia.com/Extensor_Hallucis_brevis

3. http://www.wheelessonline.com/ortho/extensor_hallucis_brevis

4. Becerro de Bengoa Vallejo R., Losa Iglesias M.E., Jules K.T.  Tendon Insertion at the Base of the Proximal Phalanx of the Hallux: Surgical Implications (2012)  Journal of Foot and Ankle Surgery,  51  (6) , pp. 729-733.

5. Zelik, K.E., La Scaleia, V., Ivanenko, Y.P. et al. Eur J Appl Physiol (2015) 115: 691. https://doi.org/10.1007/s00421-014-3056-x

Ankle Rocker Revisited....

How many times have we talked about ankle rocker and its importance? So how are YOU measuring ankle rocker? Are you looking at it on the table? On the ground? Weight bearing? Knee flexed or extended (or both?). The knee is extended at initial contact, flexes through midstance, extends at terminal stance and pre swing and flexes again during swing phase until extending at the end of terminal swing for initial contact again.

What you see on the table may not (and many times doesn't)  translate to real life. Someone with limited ankle dorsiflexion non weight bearing may have normal amounts during gait and vice versa. With gravity in place and a functioning (or malfunctioning) vestibular system, things can change rapidly. Remember that the vestibular system drives the extensors and if inhibited, you will often have flexor dominance. Talk about a tight gastroc/soleus group!

"These findings indicate that nonweightbearing and weightbearing measurements of ankle DF PROM with knee extension should not be used interchangeably and that weightbearing ankle DF PROM with the knee extended is more appropriate for estimating ankle DF during gait."

Kang MH, Oh JS. Relationship Between Weightbearing Ankle Dorsiflexion Passive Range of Motion and Ankle Kinematics During Gait. J Am Podiatr Med Assoc. 2017 Jan;107(1):39-45. doi: 10.7547/14-112.

"There is no relationship between a static diagnosis of ankle dorsiflexion at 0° with dorsiflexion during gait. On the other hand, those subjects with less than -5° of dorsiflexion during static examination did exhibit reduced ankle range of motion during gait."

Gatt A, De Giorgio S, Chockalingam N, Formosa C. A pilot investigation into the relationship between static diagnosis of ankle equinus and dynamic ankle and foot dorsiflexion during stance phase of gait: Time to revisit theory? Foot (Edinb). 2017 Mar;30:47-52. doi: 10.1016/j.foot.2017.01.002. Epub 2017 Feb 6.

Being a gait geek offers you a unique perspective in many situations.

Perhaps you have been with us for some time now and would like to check your gait acumen. If you are new, or these terms are foreign to you; search here on our blog through hundreds of posts to become more comfortable with some of the vocabulary.

Watch this video a few times (we slowed it down for you) and write down what you see.

Did you see all of these in this brief video?

• bilateral loss of hip extension

• bilateral loss of ankle rocker

• less ankle rocker on right

• bilateral increased progression angle  

• dip in right pelvis at right heel strike

• arm swing increased on R

The Gait Guys. Increasing your gait competency each and every day.

special thanks to NL for allowing us to use this video footage.