Abductory Twist: Throw the kitchen sink at it

The abductory twist is not a diagnosis or even necessarily a problem, but is an observation that is noted when people are walking or running. An abductory twist is observed as a sudden medial twist of the heel (calcaneus) just as the weight comes off the ground when walking.

What does an abductory twist look like?

This video from Dr Kevin Kirby, DPM does a good job of explaining the abductory twist:

Once you are aware of what an abductory twist looks like and this video does a good job at describing it, it can then be relatively easy to spot.

Don’t confuse an abductory twist with a medial heel whip

There is some confusion surrounding the use of terminology about the ‘abductory twist’. This article is about that observation that occurs with the sudden abduction twist of the heel just as weight comes off the heel and the forefoot is still on the ground (as seen in the above video). If you want to call that observation something else, then that is fine, but this article is still about that observation.

There is another observation that can happen later in the gait cycle that I and others call a medial heel whip. This tends to occur when the foot is off the ground and can be seen as a circumduction type motion of the foot during the swing phase. Some people mix up the terminology and understanding of this medial heel whip and the abductory twist.

What causes the abductory twist?

There are two quite plausible theories that can explain why it occurs, that I first discussed here:

Overpronation theory:
If the foot is in a pronated position beyond about midstance or around 50% of the stance phase, this will cause the foot is to try and internally rotate the tibia at the same time the opposite leg and is in the swing phase and moving forward. This swing phase leg is rotating the pelvis and the leg externally. This means that while the pronated foot is trying to rotate the tibia internally and the other leg and pelvis is trying to rotate it externally. Can you see the conflict that is happening? When an abductory twist occurs, it is assumed that initially the pronated foot causing the internal rotation force wins this conflict and foot does not supinate to accommodate that proximal external rotation moment that is coming from above due to the action of the other leg. However, as soon as some weight comes off the heel, the friction between the ground and foot can no longer resist that external rotation which is coming from above and all the built up energy is released in the form of the abductory twist or that sudden abduction of the rearfoot when friction no longer holds the heel in place.

Sagittal plane block theory:
The second alternative plausible theory is that there is something blocking motion at the first metatarsophalangeal joint (big toe joint). As the heel starts to come off the ground that joint has to start flexing so that the body can move forward over the ground. One of the ways the the body can move around that restriction of motion to move forward is to roll off the medial side of the first metatarsophalangeal joint so the joint does not have to dorsiflex, resulting in the abductory twist at the heel. A number of different entities can block motion at that joint, such as hallux rigidus, a functional hallux limitus, or a very high force to get the windlass mechanism working, or wearing footwear that is very stiff in the forefoot.

Both of the above theoretical mechanisms to explain an abductory twist are plausible.

You do occasionally come across suggestions that dysfunction at the hip or some other proximal problem can cause an abductory twist. I have never seen it. Every abductory twist I have seen can be explained by one of the above possible mechanisms. However, proximal problems can cause the medial heel whip, so when you see or hear about such suggestions, make sure they are talking about a true abductory twist (like described in this article) or confusing it with the medial heel whip.

What can be done to treat and abductory twist

Firstly, as the abductory twist is not a diagnosis, but is just an observation of something that happens during a gait analysis, the question has to be asked is that does it even need treating? What or if needs to be done about it will depend on what the problem is that is being assessed is. What is the cause of the pain? What is the cause of the abnormal gait pattern? And is that gait pattern related to the cause of the pain? A lot of questions need to be asked and answered before a decision can be made.

If you really to need to do something to treat an abductory twist, then you address the cause: Foot orthotics that have design features to make sure the foot is not in a pronated position past 50% of the stance phase are going to help and so will interventions aimed at facilitating the block of sagittal plane motion at the big toe joint of the foot. Which intervention for that will depend on what is causing the block.

Exercises for an abductory twist:
There are generally no exercises that can be done to help an abductory twist unless a muscle weakness is the reason for the foot being in a pronated position past midstance and that is a very uncommon reason or a muscle weakness is a cause of the sagittal plane block and I know of no muscle weakness that can cause that.
However, exercises can help the medial heel whip, so when you see exercises advocated for an abductory twist, make sure that it is being advised for a true abductory twist as described here in this article or if they are confusing it with a true medial heel whip.

Personal opinion on the abductory twist

At the end of the day its not a big issue. The abductory twist is a nice observation to make. It used to be fun showing the students this during them learning how to do a gait analysis and they finally see one and the lights go on. Sadly that did tend to make it a bigger issue than it really is and they focus on that rather on what really matters.

Also, be careful when you see, read and hear about the abductory twist due to the confusion with the abductory twist and medial heel whip. Make sure it is clear which one they are talking about and it they are mixing up the conditions (they are two different things) and the terminology.

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