What is it?
The abductory twist is a sudden medial snap of the heel just has it comes off the ground (not to be confused with a medial heel whip which is something that happens later in the gait cycle when the rest of the foot comes of the ground). It is a reasonable common observation made during a gait analysis.
What does it look like?
Is it of any significance?
Not really. It is an observation and not a diagnosis. It typically occurs in an overpronated foot that may or may not need to be treated.
What causes it?
there are two hypotheses as to what might be causing an abductory twist:
1. As the foot ‘overprontes’ it rotates the tibia internally an excessive amount at the same time that motion at the hip above is trying to externally rotate the limb. As the heel comes off the ground, that lack of friction between the ground and the foot suddenly allows that external rotation to happen. This could explain the abductory twist.
2. A functional limitation of dorsiflexion at the first metatarso-phalangeal joint will limit dorsiflexion at the joint as the heel comes off the ground, so the foot has to suddenly abduct to roll around that joint to move forward.
Many like to claim that this is due to functional problems around the hip, but those that do that are generally confusing the abductory twist with the medial heel whip that occurs later in the gait cycle and could be due to issues around the hip.