Sometimes you need to run that valgus post clear back to the heel!

A valgus post assists in pronation. Some fols have modereate to severe internal tibial torsion and need to be able to pronate more to get the knee into the saggital plane for patello femoral conflicts. They usually run from the tail of the 5th metatarsal forward, but sometimes need to run it clear back to the heel to get enough pronation to occur.

Forefoot valgus: A fixed structural defect in which the plantar aspect of the forefoot is everted on the frontal plane relative to the plantar aspect of the rearfoot; the calcaneum is vertical, the mid tarsal joints are locked and fully pronated

Want to know more? Join us Wednesday evening: 5 PST, 6 MST, 7 CST, 8 EST for Biomechanics 309: Focus on the forefoot on onlinece.com.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

Fore foot types: Differences between forefoot varus and forefoot supinatus.

Certainly this can be a contraversial topic. Perhaps this will help clear up some questions.

Supination of the forefoot that develops with adult acquired flatfoot is defined as forefoot supinatus. This deformity is an acquired soft tissue adaptation in which the forefoot is inverted on the rearfoot. Forefoot supinatus is a reducible deformity. Forefoot supinatus can mimic, and often be mistaken for, a forefoot varus. A forefoot varus differs from forefoot supinatus in that a forefoot varus is a congenital osseous deformity that induces subtalar joint pronation, whereas forefoot supinatus is acquired and develops because of subtalar joint pronation (1).

A Forefoot Varus induces STJ pronation whereas a Forefoot Supinatus is created because of STJ pronation (2).

As the foot experiences increased subtalar joint (STJ) pronation moments during weightbearing activities (as in forefoot supinatus) , the medial metatarsal rays will be subjected to increased dorsiflexion moments and the lateral metatarsal rays will be subjected to decreased dorsiflexion moments. Over time, this increase in STJ pronation moments will tend to cause a lengthening of the plantar ligaments and medial fibers of the central component of the plantar aponeurosis and a shortening of the dorsal ligaments in the medial longitudinal arch. As a result, the influence of increased STJ pronation moments occurring over time during weightbearing activities will tend to cause the following (3):

1. An increase in inverted forefoot deformity.
2. A decrease in everted forefoot deformity.
3. A change in everted forefoot deformity to either a perpendicular forefoot to rearfoot relationship or to an inverted forefoot deformity.

More on the forefoot tomorrow evening on onlinece.com: Biomechanics 309. Join us!

1. Clin Podiatr Med Surg. 2014 Jul;31(3):405-13. doi: 10.1016/j.cpm.2014.03.009. Forefoot supinatus. Evans EL1, Catanzariti AR2.

2. https://kenva.wordpress.com/…/…/forefoot-varus-or-supinatus/

3. http://www.podiatry-arena.com/podiatry-forum/showthread.php…

Forefoot Varus or Forefoot Supinatus?

Forefoot varus is a fixed, frontal plane deformity where the forefoot is inverted with respect to the rearfoot. Forefoot varus is normal in early childhood, but should not persist past 6 years of age (i.e. when developmental valgus rotation of forefoot on rearfoot is complete, and plantar aspects of fore- and rearfoot become parallel to, and on same plane as, one another (1)

Forefoot supinatus is the supination of the forefoot that develops with adult acquired flatfoot deformity. This is an acquired soft tissue adaptation in which the forefoot is inverted on the rearfoot. Forefoot supinatus is a reducible deformity. Forefoot supinatus can mimic, and often be mistaken for, a forefoot varus. (2)

A forefoot varus differs from forefoot supinatus in that a forefoot varus is a congenital osseous where a forefoot supinatus is acquired and develops because of subtalar joint pronation.

“Interestingly, only internal rotation of the hip was increased in subjects with FV – no differences were present in hip adduction and knee abduction between subjects with and without FV. The authors nevertheless conclude that FV causes significant changes in mechanics of proximal segments in the lower extremity and speculate that during high-speed weight-bearing tasks such as running, the effects of FV on proximal segments in the kinetic chain might be more pronounced.”

We wonder if the folks in this study had a true forefoot varus, or actually a forefoot supinatus (3).

The Gait Guys

1. Illustrated Dictionary of Podiatry and Foot Science by Jean Mooney © 2009 Elsevier Limited.

2. Evans EL1, Catanzariti AR2. Forefoot supinatus.
Clin Podiatr Med Surg. 2014 Jul;31(3):405-13. doi: 10.1016/j.cpm.2014.03.009.

3. Scattone Silva R1, Maciel CD2, Serrão FV3. The effects of forefoot varus on hip and knee kinematics during single-leg squat. Man Ther. 2015 Feb;20(1):79-83. doi: 10.1016/j.math.2014.07.001. Epub 2014 Jul 12.

Keeping it Objective.

For clinicians and some die hard foot geeks, we often like to keep things objective. What could be more objective than an angular measurement? A few important measurements when examining or radiographing feet can give us information about clinical decision making (not that we suggest radiographs for mensuration purposes unless you are a surgeon, but when they are already available, why not put them to good use ?). When things fall outside the accepted range, or appear to be heading that way, these numbers can help guide us when to intervene. 

Hallux valgus refers to the big toe headed west (or east, depending on the foot and your GPS). In other words, the proximal and distal phalanyx of the great toe (hallux) have an angle with the 1st metatarsal shaft of typically > 15 degrees. This angle, called the Hallux Valgus Angle (HVA above) is used to judge severity, often for surgical intervention purposes but can guide conservative management as well. 

Metatarsus Primus Varus (literally, varus deformity of the 1st metatarsal) often accompanies Hallux Valgus. It describes medial deviation of the 1st metatarsal shaft, greater than 9 degrees. This angle is called the intermetatarsal angle and is measured by the angle formed by lines drawn parallel along the long axis of the 1st and 2nd metatarsal shafts. 

One other measurement is the Distal Metatarsal Articular Angle, which measures the angle between the metatarsal shaft and the base of the distal articular cap (ie, where the cartilage is) of the 1st metatarsal. This typically should be less than 10 degrees, preferably less than 6 degrees. Remember, these are static angles, things can change with movement, engagement, weight bearing strategies and shoes. What you see statically does not always predict dynamic angles and joint relationship.s

Are you doing surgery? Perhaps, as a last resort. Hallux valgus and metatarsus primus varus can be treated conservatively.

How do you do that?

The answer is both simple and complex.

The simple answer is: anchor the head of the 1st ray and normalize foot function. This could be accomplished by:

  • EHB exercises to descend the head of the 1st metatarsal
  • exercise the peroneus longus, to assist in descending the head of the 1st metatarsal
  • short flexor exercises, such as toe waving, to raise the heads of the lesser metatarsals relative to the 1st
  • work the long extensors, particularly of the lesser metatarsals to create balance between the flexors and extensors
  • consider using a product like “Correct Toes” to normalize the pull of the muscles and physically move the proximal and distal phalanyx of the hallux
  • wear shoes with wide toe boxes, to allow the foot to physically splay
  • consider using an orthotic with a 1st ray cut out, to help descend the head of the 1st metatarsal

This is by no means an exhaustive list and you probably have some ideas of your own. 

The complex answer is that in the above example, we have only included conservative interventions for the foot and have not moved further up the kinetic (or neurological chain). Could improving ankle rocker help create more normal mechanics? Would you accomplish this by working the anterior leg muscles, the hip extensors, or both? Could a weak abdominal external oblique be contributing? How about a faulty activation pattern of the gluteus medius? Could a congenital defect or genetic be playing a role? We have not asked “What caused this to occur in the 1st place?”

Examine your patients and clients. Understand the biomechanics of what is happening. Design a rehab program based on your findings. Try new ideas and therapies. it is only through our failures that we can truly learn.

The Gait Guys

references used:

http://www.bjjprocs.boneandjoint.org.uk/content/90-B/SUPP_II/228.3

http://www.slideshare.net/ANALISIS/hallux-valgus-2008-pp-tshare

http://www.orthobullets.com/foot-and-ankle/7008/hallux-valgus

http://www.slideshare.net/bahetisidharth/hallux-valgus-31768699?related=1

When the big guy heads medially….Game Changer

Lately we have been seeing a lot of bunions (hallux valgus). While doing some research on intermetatarsal angles (that’s for another post) we came across the nifty diagram you see above. 

Regardless of the cause, as the 1st metatarsal moves medially, there are biomechanical consequences. Lets look at each in turn. 

  • the EHB (extensor hallucis brevis) axis shifts medially. this muscle, normally an extensor of the proximal phalanyx, now becomes more of an abductor of the hallux. It’s secondary action of assisting the descent of the head of the 1st metatarsal no longer happens and it actually moves the base of the proximal phalanyx posteriorly, altering the axis of centration of the joint, contributing to a lack of dorsiflexion of the joint and a hallux limitus
  • Abductor hallucis becomes more of a flexor, as it moves to the plantar surface of the foot. Remember, a large percentage of people already have this muscle inserting more on the plantar surface of the foot (along with the medial aspect of the flexor hallucis brevis), so in these folks, it moves even more laterally, distorting the proximal phalanx along its long axis (ie medially) see this post here for more info
  • Flexor hallucis brevis moves more laterally. Remember this muscle houses the sesamoid bones before inserting onto the base of the proximal phalannx; the medial blending with the abductor hallucis and the lateral with the adductor hallucis. Because the sesamoid bones have moved laterally, they no longer afford this muscle the mechanical advantage they did previously and the axis of motion of the 1st metatarsal phalangeal joint moves dorsally and posterior, contributing to limited dorsiflexion of that joint and a resultant hallux limitis. The lateral movement of the sesamoids also tips the long axis of the 1st metatarsal and proximal phalanyx into eversion. In addition, the metatarsal head is exposed and is subject to the ground reactive forces normally tranmittted through the sesamoids; often leading to metatarsalgia. 
  • Adductor hallucis: this muscle now has a greater mechanical advantage  and because the head of the 1st ray is not anchored, acts to abduct the hallux to a greater degree. The now everted position of the hallux contributes to this as well

As you can see, there is more to the whole than the sum of the parts. Bunions have many biomechanical consequences, and these are only a small part of the big picture. Take you time, learn your anatomy and examine everything that has a foot!

See you in the shoe isle…

Ivo and Shawn

pictures from: http://www.orthobullets.com/foot-and-ankle/7008/hallux-valgus and http://www.stepbystepfootcare.com/faqs/nakedfeet/

When the big guy heads medially….Game Changer

Lately we have been seeing a lot of bunions (hallux valgus). While doing some research on intermetatarsal angles (that’s for another post) we came across the nifty diagram you see above. 

Regardless of the cause, as the 1st metatarsal moves medially, there are biomechanical consequences. Lets look at each in turn. 

  • the EHB (extensor hallucis brevis) axis shifts medially. this muscle, normally an extensor of the proximal phalanyx, now becomes more of an abductor of the hallux. It’s secondary action of assisting the descent of the head of the 1st metatarsal no longer happens and it actually moves the base of the proximal phalanyx posteriorly, altering the axis of centration of the joint, contributing to a lack of dorsiflexion of the joint and a hallux limitus
  • Abductor hallucis becomes more of a flexor, as it moves to the plantar surface of the foot. Remember, a large percentage of people already have this muscle inserting more on the plantar surface of the foot (along with the medial aspect of the flexor hallucis brevis), so in these folks, it moves even more laterally, distorting the proximal phalanx along its long axis (ie medially) see this post here for more info
  • Flexor hallucis brevis moves more laterally. Remember this muscle houses the sesamoid bones before inserting onto the base of the proximal phalannx; the medial blending with the abductor hallucis and the lateral with the adductor hallucis. Because the sesamoid bones have moved laterally, they no longer afford this muscle the mechanical advantage they did previously and the axis of motion of the 1st metatarsal phalangeal joint moves dorsally and posterior, contributing to limited dorsiflexion of that joint and a resultant hallux limitis. The lateral movement of the sesamoids also tips the long axis of the 1st metatarsal and proximal phalanyx into eversion. In addition, the metatarsal head is exposed and is subject to the ground reactive forces normally tranmittted through the sesamoids; often leading to metatarsalgia. 
  • Adductor hallucis: this muscle now has a greater mechanical advantage  and because the head of the 1st ray is not anchored, acts to abduct the hallux to a greater degree. The now everted position of the hallux contributes to this as well

As you can see, there is more to the whole than the sum of the parts. Bunions have many biomechanical consequences, and these are only a small part of the big picture. Take you time, learn your anatomy and examine everything that has a foot!

See you in the shoe isle…

Ivo and Shawn

pictures from: http://www.orthobullets.com/foot-and-ankle/7008/hallux-valgus and http://www.stepbystepfootcare.com/faqs/nakedfeet/