Foot Progression Angle Exaggeration: External Tibial Torsion
Take a look at the tibial tuberosity and then where you think the 2nd metatarsal head would be. What do you see? The 2nd metatarsal is lateral to the tibial tuberosity. You are looking at external tibial torsion.
Lets see how this external tibail torsion behaves during a knee bending. Observe the medial drift of the knee during weight bearing knee flexion. Many folks would say that the problem here is the increased foot prontation, but that is not where the problem lies, that is where many of the forces are funneling though. The client is pronating more because the external tibial torsion that is creating this appearance has put the knee inside the foot tripods region of stability.
In external tibial torsion there is an external torsion or a “twist” along the length of the tibia (diaphysis or long section). This occurs in this example to the degree that the ankle joint (mortise joint) can no longer cooperate with sagittal knee joint. When taking a client with external tibial torsion and pre-postioning their foot in a relatively acceptable/normal foot progression angle there is a conflict at the knee, meaning that the knee cannot hinge forward in its usual sagittal plane. In this case with the foot progression angle smaller than what this client would posture the foot, the knee the knee will be forced to drift medially.
Are you looking for torsions of the lower limb in your clients ?
Are you forcing them into foot postures that look better to you but that which are conflicting to your clients given body mechanics ? Would you correct this client’s foot turn out (increased progression angle) ? IF you did you would likely cause them knee pain in time. Would you put them into a stability shoe to try and control the pronation ? Again, you are likely to draw their knee outside the saggital knee hinge that is presently pain free. There is more to shoe fit that just looking at the foot. First do no harm is our mantra !
Remember, telling someone to turn their foot in or out because it doesn’t appear correct to your eyes can significantly impair either local or global joints , and often both. Torsions can occur in the talus, the tibia and the femur.
Furthermore, torsions can have an impact on foot posturing at foot strike and affect the limbs loading response, from foot to core and even arm swing can be altered. Letting your foot fall naturally beneath your body does not mean that you have the clean anatomy to do so without a short term or long term cost.
This is some of the toughest stuff you will deal with clinically. The fence is narrow, if you do to little correction you fall off the fence into the wrong yard and create problems. If you do to much correction you get the same result. These torsional issues are a delicate balancing act many times. You first have to know what you have, then you have to know where the fix is, and then how much is safe. Tricky stuff. This is exactly why in some folks a stability shoe can be magic or tragic and in others dropping into zero drop minimalism can be magic or tragic.
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Shawn and Ivo, The Gait Guys