Category Archives: Biomechanics

The Abductory Twist

The abductory twist is an observation which is found during an observation of the walking. Just as the heel starts to unweight or raise up the ground there’s a fast sudden abduction or twist seen of the heel. This is a commonplace finding during a gait evaluation, but its clinical value is of some discussion.

There are a number of reasons for an abductory twist. The first is that because rearfoot is pronating (rolling medially at the rearfoot) this is attempting to internally rotate the leg. Simultaneously the other leg is in the swing period moving forward and is wanting to externally turn the lower limb. The lower limb is ‘battling’ with these two opposite motions. Friction between the floor and the heel holds the heel from moving. The instant weight starts to come off the heel, the external rotation force from above can now abduct the rearfoot and it does so easily. A second explanation is that there is a condition at the great toe joint in which it fails to enable dorsiflexion correctly. This might be a hallux rigidus, a functional hallux limitus or a issue with the windlass mechanism that affects movement at the great toe joint. As this dorsiflexion is difficult to start, the body abducts the heel to maneuver sideways around that joint. Another reason which is often only found in the physical therapy literature is that the problem is as a result of control of motion around the hip joint. In that literature this is described as a medial heel whip.

The cause of debate about the clinical significance of an abductory twist is that it is merely an observation observed when doing a gait assessment that is the result of another thing (for example, the loss of friction with the ground, an issue at the big toe or hallux joint or the hip joint). If it is a problem, then therapy is directed at what is triggering the abductory twist or medial heel whip rather than aimed at the abductory twist itself. The treatment choices to do away with it is going to be very diverse dependent on what is the preferred treatment decision for what’s causing it.