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 tiphere).
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.
‘Overpronation’ is a term that has a mixed pedigree with some thinking it the holy grail of the cause of injuries in runners to it being a nonsensical term of no importance. There are so many myths and misundertandings about ‘overpronation’. The problem starts with the very definition of what it is. In lay terms pronation is a rolling inwards of the foot at the ankle joint and a lowering of the arch of the foot, so overpronation is when there is too much of that. The problem here is an agreement of what is too much and what is normal and there is hardly what could be called a consensus. For a long time, overpronation was considered a cause of overuse injuries in runners and hence its importance. Foot orthotics are widely used to treat this and all the outcome studies pretty much show that they work. Running shoes were and still are prescribed based on no, moderate or severe amounts of pronation. The problem arises that many of the risk factor studies in runners were showing the foot overpronation was not a problem. Some studies were showing it was a problem, so the research evidence was getting everyone confused. Even the health professionals and running shoe companies were giving mixed signals about this, so no wonder the running community were getting confused and the myths developing.
Fortunately we are now in the position were a powerful meta-analysis has combined all the data from all the risk factor and overpronation studies and they concluded that there is a small, but still statistically significant, risk of overuse injury from overpronation. Unfortunately the publication of this meta-analysis and systematic review has not put and end to the cherry picking of those who want to make their point one way or the other, though there are somewebsites that do give sound advice.