ETT and Hip Extension
Not Extra Terrestrial Tricks, but rather External Tibial Torsion. How it effects hip extension.
We received this question from Matthew P on our Facebook post from 8/1 (original post from here) which was based on this article, and thought it would make an excellent opportunity to teach.
“I looked at this yesterday and had actually first come across it a year or more ago when I was trying to find some resources for femoral torsion. You guys are about the only ones discussing at length the impact and implication of adult femoral torsion.
Re: tibial torsion and your post yesterday saying that > 30deg external torsion can affect both knee and hip extension, what I still don’t understand is the mechanism behind the hip limitation. How would that torsion translate through the leg to the hip?”
There are a few things we need to remember to make sense of this:
- tibial torsion is the angular difference between the tibial plateau and distal tibial malleoli and refers only to the tibia, not the entire lower extremity (see top photo)
- pronation can occur in the rear foot, mid foot, and fore foot
- pronation causes internal spin of the leg and thigh, due to plantar flexion, eversion and abduction of the talus (see middle photo)
- internal spin of the hip causes posterior translation of the femoral head via the “glide and roll” phenomenon
- these are appropriate mechanics during the 1st ½ of the gait cycle (initial contact to mid stance)
- pronation is one of the 4 shock absorbing mechanisms (pronation, ankle dorsiflexion, knee flexion, hip flexion) of the lower extremity
now try this (yes, at home!)
- flex your knee
- internally rotate you leg
- allow your arch to flatten
- try and extend your hip
Remember these facts about supination
- supination is initiated by the swing phase leg as it starts in early swing and continues to terminal swing (see third picture)
- supination (from full pronation), should occur from midstance to pre swing
- supination makes the foot into a “rigid lever” to transpose forces from above the foot into the foot and allow for propulsion (see third picture)
- supination involves external rotation of the lower leg and thigh (see pictures 3 and 4)
- external rotation of the hip is accompanied by anterior glide of the femoral head via the “glide and roll” phenomenon
- this position puts the gluteal muscles (max and posterior fibers of the gluteus medius) at a mechanical advantage
now try this:
- extend your knee
- externally rotate your leg
- you should have a full arch at this point
- try and extend your hip
What did you (hopefully) learn?
- When the hip is in an externally rotated position it is easier to extend; the femur head moves anteriorly, the femoral joint capsule becomes tighter and stability is created
- when the hip is internally rotated, it is more difficult to extend
- the femur head glides posteriorly, changing the axis of rotation of the joint
- the gluteus maximus and posterior fibers of the gluteus medius are at a mechanical disadvantage
OK. Got it? We sure hope so! Excellent question, Matthew. Thanks for the opportunity to teach this concept.
The Gait Guys. Taking you closer to mastering the gait cycle with each post.
