I recently started teaching a new group of Functional Therapists, and over the first weekend we covered modules 1 and 2: Observing and Predicting Human Motion and Mastering Movement and Muscles of the Lower Limb. Part of this first weekend is to bring everyone to the same understanding of how bones move, how joints feel and how muscles react to those joint motions.

One of the hardest things to get your head around when you start is how to name joint movements, and again there are a few that always trip you up because they are a little counter-intuitive. The one that springs to mind is knee abduction, so we’ll use that as our example.

Throughout Functional Therapy we are trying to gain a greater understanding of gait as a foundation movement, and so at the knee we go through the motions in all three planes as a front leg and a back leg. As a front leg, the knee is flexing, abducting and internally rotating, and it is the abduction at this point that causes so much confusion.

If we are talking about the right leg, then we know that in the frontal plane the tib and fib are tilting left and the femur is still tilting right, which gives you a knee joint motion of abduction through both bones moving in opposite directions. Sounds simple when you write it like that, but the confusion comes when you look at the knee motion in function.

I think this is partly because in anatomy and human movement we are taught that frontal plane motion is measured from the mid-line of the body, with movement towards the mid-line being adduction and movement away from the mid-line being abduction. Makes sense for some motions, but it doesn’t work in the case of knee abduction. In this case the limb moves towards the mid-line of the body, which would suggest the knee is adducting, but we are not talking about where the limb moves to, we want to know what the tibia is doing relative to the femur. So the mid-line of the body is irrelevant, it’s the mid-line of the knee joint that is important.

This is a brilliant insight from John Tran who described the knee motions like this and it makes perfect sense. If you draw a line vertically on the front of the knee, movement that moves the tibia to the outside of this line would be abduction, and movement to the inside would be adduction. Makes understanding adduction/abduction much easier, particularly when you are looking at the knee in function.

So, in future I will be using this thought process in explaining motion at the knee, or any other joint motions that cause confusion. All thanks to John Tran. 🙂

Neil Poulton