The abductory twist is something that we see frequently in clinical practice when doing a gait analysis and is commonly associated with overpronation. This video on You Tube explains it really well (hat tip here).
It is not a diagnosis, but just a sign noted during a gait analysis (interesting confusion regarding a patient thinking it was a ‘diagnosis’ here). There is also plenty advice for dealing with this (see here). It also is called a medial heel whip, a term this is more commonly used by physical therapists.