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Abductory Twist

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Lab Guy, Oct 7, 2013.

  1. Lab Guy

    Lab Guy Well-Known Member

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    I have a question to bring further clarity to my understanding of the abductory twist seen in late midstance at heel-off. Lets say were dealing with a flexible flatfoot:

    From heel contact to midstance, the right foot is pronating and by the time the right foot reaches midstance where the Com is over the stance leg, the STJ has used up all its range of motion and is maximally pronated as is the MTJ. The tibia is internally rotating.

    From heel contact to midstance, the ipsilateral pelvis has moved from an anterior direction in relation to the swing phase/contralateral pelvis and at midstance, the right and left sides of the pelvis are parallel.

    From midstance to heel-off, the right foot is still pronated and the tibia is internally rotated when the STJ should be resupinating and the tibia beginning to externally rotate.

    The pelvis over the right stance foot is moving posterior (externally rotating) as the right hip is extending and the plevis over the left/swing foot is anterior. The right pelvis in relation to the right stance foot just before heel-off is maximally externally rotated.

    The heel now lifts off the ground and friction is now nonexistent allowing the heel to adduct as the forefoot is abducting in reponse to the released stored elastic strain energy within the right externally rotated hip and externally rotates the tibia so that the transverse rotation of the right hip and right leg are no longer mismatched.

    Is that pretty accurate?

    In OCK, the femur is internally rotating on the fixed pelvis. In CKC, does the internal rotation of the tibia transmit through the knee to the femur? I think not, I think that the pelvis is simply externally rotating on the fixed femur head within the acetabulum. Would that be correct?

    I do know that when my right foot is in late midstance and pronated I can feel the stress/tightness in my right hip but when I place an orthotic under my foot, I can no longer feel the tightness.

    I think I understand what is happening during the abductory twist that is frequently seen. Is there anything I am missing?

  2. Craig Payne

    Craig Payne Moderator

    There is also the alternative explanation that it can also occur as a compensation for a functional hallux limitus.

    I blogged about abductory twist here: http://www.runresearchjunkie.com/the-abductory-twist-during-gait/ and we had this previous threads:

    I have also just come to realize that the term 'abductory twist' is something that is unique to Podiatry. Everyone else seems to call it 'heel whip' or 'medial heel whip'.

    I checked a google keyword search tool and according to it, the term 'abductory twist' is searched for so infrequently, it shows that there a no searchs for it on a monthly basis, but 'heel whip' is generally searched for 90 times a month --> looks like the term heel whip is much more commonly used.
  3. Lab Guy

    Lab Guy Well-Known Member

    Thanks Craig, I appreciate your quick reply.

  4. Ian Linane

    Ian Linane Well-Known Member

    Funny, as I have often heard it called heel whip or medial heel whip, long before I understood as abductory twist.
  5. Craig Payne

    Craig Payne Moderator

    I honestly have never come across the term before!!!! The first I learnt of it was when someone tweeted a comment in response to my blog post on it a month or so ago!
  6. Ian Linane

    Ian Linane Well-Known Member

    To be honest Craig I worked far more with physios than pods in my early years and probably picked it up from them. Later I heard it from pods and, if memory serves me right really came across the term Abductory Twist in more recent years and here on pod arena. There again, podiatry wise, I was not brought up properly so that could account for it.
  7. efuller

    efuller MVP

    I think you have the general idea. I'll try my wording and you can see if it simpler than yours, or not.

    In the stance phase, before heel lift, the structures above are applying an eternal rotation moment to the tibia (external rotation of tibia relative to ground) (One of the hard parts of reading the info above is understanding the frame of refernce of the motion.) The friction of the foot on the floor prevents the foot from externally rotating relative to the ground. The external rotation moment applied to the tibia will also try and cause a supination moment at the STJ. If pronation moment from other sources (e.g. cener of pressure lateral to STJ axis) is greater than the supination moment from external rotation of the tibia, then the STJ will stay pronated. When there is a net pronation moment at the STJ, the leg cannot externally roatate relative to the foot.

    So, when the heel lifts off of the ground, there is less friction preventing external roatation of the foot relative to the ground. The fore foot is still on the ground, so extenal rotation moment applied to the tibia will cause the heel to move medially. Thus the abductory twist, or maybe should be called heel whip.

  8. Here's the video I put up on my YouTube site on Abductory Twist about five years ago. See if my explanation makes any better sense.:drinks

    Last edited by a moderator: Sep 22, 2016
  9. Here is another video of the same subject from my Abductory Twist video where the elastic strain energy within the hip is demonstrated. The rapid external rotation of the foot after release of the internally rotated hip shows the potential for external rotation acceleration of the whole limb from stretching the ligaments, tendons, and muscles which cross the hip joint. This external rotation acceleration of the whole limb at the hip joint occurs due to release of stored elastic strain energy within the vertical reference axis of the hip joint and is the most likely cause of the rapid external rotation of the foot that is commonly seen in Abductory Twist.

    By the way, both of these videos were taken in the Gait Lab at the Shriner's Hospital in Sacramento. The subject is one of my patients who, interestingly enough, also has a PhD in Biomechanics.

    Last edited by a moderator: Sep 22, 2016
  10. Lab Guy

    Lab Guy Well-Known Member

    Thanks Eric and Kevin for your replies, I appreciate your responses greatly.

    I get what you are both saying and I appreciate the videos. I also understand the mechanics/physics behind the pronated late midstance foot. I think I know where I was confused.

    In OKC, the pelvis is stable, and the lower limb is internally rotating under the pelvis in your demonstration of elastic strain energy. There is kinematic coupling of the tibia, knee and femur.

    However, in CKC, in your gait video, the tibia is internally rotating but now the kinematic coupling of the tibia, knee and femur does not occur as the femur is not moving under the pelvis but rather the pelvis is moving over the femur/leg. During gait in CKC, the elastic strain energy is built up from the tissues crossing the hip joint from the pelvis externally rotating when the tibia is doing the opposite, internally rotating.

    So, I think I see the light and understand where my confusion was. I was thinking the pelvis was rotating externally while the tibia and the femur was also internally rotating. But there is no kinematic coupling in CKC as there is in OKC and its just the elastic strain on the tissue of the hip from the externally rotated pelvis that is not in sync what is happening with the planted and pronated foot and internally rotated tibia. This is then causing a shorter stride versus the foot that resupinates in terminal stance.

    I believe I got this right if not, please let me know as I can be a bit dense, thanks for the patience and insight.

  11. efuller

    efuller MVP

    Again I think you have it.
    Looking at the stance phase hip, there are three possibilites for the kinetics in the transverse plane. Looking from above with the rigth leg in stance, The hip can be accelerating in a clockwise direction, staying the same speed in the clockwise direction or decelerating in a clock wise direction relative to the femur. If the hip is reaching its end of range of motion in the clock wise rotatation the ligaments will become tight. At this point the pelvis will be applying an external rotation moment to the femur and the femur will be applying a (same view) a counter clockwise moment to the pelvis. (It doesn't necessarily have to be the ligaments, it could be the hip musculature.)

    Whether or not the femur externally rotates depends on the moments at the interfaces below it. Transverse plane motion can occur at the knee (femur relative to the tibia,) at the STJ (talus relative to calcaneus) or foot and the floor.)
    If external rotation of the femur is allowed at any of those locations the femur will externally rotate and allow greater clockwise rotation (right leg in stance viewed from above) of the pelvis, relative to the ground, which, as you stated, will allow for a longer stride.

    Maybe more than you wanted.....
  12. Steve:

    In addition to Eric's excellent comments, I think that in order to explain abductory twist with clarity, we must be careful of our terminology and frames of reference.

    I wrote a four page Precision Intricast Newsletter in July 2003 titled "Biomechanics of Abductory Twist" that is now published in my third book (Kirby KA: Foot and Lower Extremity Biomechanics III: Precision Intricast Newsletters, 2002-2008. Precision Intricast, Inc., Payson, AZ, 2009, pp. 113-116).

    Here is an excerpt from the newsletter which explains abductory twist biomechanics:

    Here is one of the illustratons from my book showing the transverse plane rotations of the pelvis over the planted foot during one step.
  13. Lab Guy

    Lab Guy Well-Known Member

    Thanks Eric and Kevin! I had a good understanding of it but I was making it much more complicated. I get it completely, its very crystal clear and I can move on.

    Thanks for your time and patience in bringing clarity to my understanding and posting your videos and newsletter. Both of you are phenomenal teachers.

  14. Steven:

    You should plan on visiting Zaragoza next February to hear Eric, Simon Spooner, Craig Payne and myself all lecture along with other international and Spanish speakers in beautiful Spain. The Spanish podiatrists really know how to host a great seminar!!

  15. Deka08

    Deka08 Active Member

    Excellent thread. Thanks.
    Kevin, I am in the market for a copy of your intricast newsletter book.
    The link on the advert on pod arena send sme to a page that does not work, and amazon tells me they are out of stock. Where else can i get a copy?
  16. Craig Payne

    Craig Payne Moderator

    I just writing another piece on this .... can someone relate to me the story that I recall hearing a number of years ago about what this got called at CCPM ... something to do with the squeak on the linoleum floor - Kevin? Eric? - do you recall this story?
  17. Lab Guy

    Lab Guy Well-Known Member


    Thanks for the heads up, sounds like a lot of fun. I am going to see what kind of airline and hotel discounts I can get using my CDP points :dizzy:

  18. Derek:

    They have been available at the Precision Intricast website for the last few years: http://www.dpmlab.com/html/bookreview.html
  19. Craig:

    The abductory twist was always called an abductory twist, not a "heel whip" or "medial heel whip" when I was a student at CCPM from 1979 - 1983. In fact, I never heard the term "heel whip" until about 10-15 years after graduating from CCPM.

    I don't know what you mean about "squeak on the linoleum floor" but to demonstrate abductory twist we always had the podiatry students walk barefoot on the lineoleum floor at CCPM, due to the increased linoleum floor-foot friction, versus having them walk on the carpeted hallway. In other words, linoleum floors and bare feet always produced the most dramatic abductory twists.

    The term "abductory twist" was used universally for this gait phenomenon by the Biomechanics Faculty at CCPM including John Weed, Ron Valmassy, Chris Smith, Bill Sanner, John Marczalec, Lester Jones, Jack Morris, Paul Scherer, Rich Blake and Richard Bogdan. In general, Chris Smith took the most time talking about abductory twist and said it was due to "unresolved pronation at the instant of heel off". I believe that this term probably originated back in the 1970s when Mert Root was still teaching biomechanics at CCPM.

    When I was a Biomechanics Fellow in 1984-1985, CCPM had acquired a slow motion black and white video camera and monitor setup, which was hi-tech for that time, that I spent a lot of time with. I used the slow motion video setup to show my podiatry students slow motion videos of abductory twist and other interesting walking and running gait phenomena. Viewing gait in slow motion really helps students to appreciate the more subtle movements in these gait phenomena.

    Hope this helps.
  20. efuller

    efuller MVP

    my recolection is pretty much the same as Kevin's. There were a number of people who had a hard time with the term abductory twist as it's the heel moving medially rather than the distal part of the foot moving laterally.
  21. Trevor Prior

    Trevor Prior Active Member

    Nice thread and explanations. The biomechanical measure for the torsion within the lower limb is termed free moment and the abductory twist / heel whip etc. is the said result. Increased free moments have been linked to stress injuries.

    Kevin, I really liked the video with the demonstration of the resistance of the leg rotation. Out of interest, in your case demonstrated, was as much rotation noted on the other leg. In other words, could the demonstration be a form of test of relative resistive forces?

  22. I believe the transverse plane rotation between the two limbs was about the same. However, if the foot plant angle (i.e. angle of gait) is more adducted than normal in one limb, then this will tend to accentuate the abductory twist, in my experience. This change in angle of gait can actually be variable from one step to the next which may be the reason that the abductory twist is more pronounced in some steps than other steps.

    Have a nice weekend.:drinks
  23. Petcu Daniel

    Petcu Daniel Well-Known Member

    A correlation between the free moment and angle of gait it was made in : Almosnino, Sivan, Tara Kajaks, and Patrick A Costigan. “The Free Moment in Walking and Its Change with Foot Rotation Angle.” Sports Medicine, Arthroscopy, Rehabilitation, Therapy, and Technology : SMARTT 1 (August 13, 2009): 19. doi:10.1186/1758-2555-1-19. http://www.ncbi.nlm.nih.gov/pubmed/19678921

    This investigation characterized the time-history pattern of the free moment (FM) during walking and, additionally, assessed whether walking with either an internally or externally rotated foot position altered the FM's time-history.
    Force plate and foot kinematic data were acquired simultaneously for 11 healthy subjects (6 males, 5 females) while walking at their self-selected comfortable speed in 3 foot rotation conditions (normal, internal and external). The FM was calculated and normalized by the product of each participant's body weight and height prior to extraction of peak FM, occurrence of peak FM in stance and net relative impulse. Differences in these values across foot rotation conditions were assessed using separate one-way, repeated measures analysis of variance and subsequent pair-wise comparisons.
    The average FM pattern during normal walking exhibits a biphasic shape: resisting inward rotation during approximately the first half of stance and outward rotation during the latter part of stance. While no differences in peak FM or net relative impulse were observed between the internal foot rotation condition and normal walking, the external foot rotation condition resulted in significantly greater peak FM and relative net impulse in comparison to normal walking.
    The differences in selected FM variables between normal walking and the external foot rotation condition are attributable to individual subject response to walking with an externally rotated foot. In this condition, some subjects displayed a FM pattern that was similar to that recorded during normal walking, while others displayed markedly larger FM patterns that are comparable in magnitude to those reported for running. The larger FM values in these latter subjects are speculated to be a result of excessive transverse plane body movements. Whilst further investigation is warranted regarding the FM time-history characteristics during walking, our results indicate that the FM may provide useful information in assessment of gait.

  24. HansMassage

    HansMassage Active Member

    I Have no connection to this story but the rhyme is obvious. The resulting twist of an old fashion sneaker toe on a linoleum floor would be a "sneaker squeaker."

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