Causes of an externally rotated leg?

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Hello I am writing this post to ask for some MSK advice. I graduated 6 months ago and do not have a great knowledge of bio-mechanics but looking to improve that.

Case:

When jogging/running on a treadmill or normal ground I can be seen to pronate. You can observe my foot collapsing and the foot everting. This is very clearly seen in a pair of neutral running trainers. During the swing phase you can see both feet externally rotating (which I believe is often done to prevent the toes catching on the ground).

I can observe that the right leg is significantly (in my opinion) externally rotated during all phases. Slightly rotated during stance phase and significantly during swing phase.

The left leg is neutral (pointing directly forward).

When I go into a good pair of brooks supportive running trainers the foot almost becomes neutral and is fairly "satisfactory".

I am looking for someone to shed some light on:

1. Why do I swing my foot round? I have very good ankle joint ROM (40-45 degrees dorsi) and would not say that I have tight Gastrocs/Soleus which could restrict this movement.
2. What is a common cause for one leg to be externally rotated. What further investigations should I undertake. What are possible solutions to this issue.

I do suffer from mild insertional achilles tendonitis occasionally but nothing severe. I have no major issues but am concerned this could cause issues later in life and as a podiatrist I think its a good learning opportunity!

Thank you in advance for any advice!

 

When you see an externally rotated position you need to figure out if there is a structural cause. When I used to teach the biomechanical evaluation I made sure the students understood which two lines they were using as a reference point to make a measurement. Starting from the top and working down. You could have an externally rotated hip. Specifically, when you externally rotate the hip there is a large available range of motion of the axis of motion of the knee joint relative to the frontal plane position of the pelvis. Then when you attempt internal rotation of the thigh relative to the pelvis (knee joint axis of motion) there is a small amount of internal rotation say less than 15 degrees. So, during gait, when the person "chooses" to function near the middle of the hip range of motion, the knee will be external.

There can also be external rotation in the tibia. Knee axis relative to ankle axis of rotation (measured as line between the malleoli) Also know as external tibial torsion.

If you can get your leg internal, (no external structural deformity), then external rotation during gait is a CNS unconscious choice.

In terms of treating an external deformity it might be a case of the treatment is worse than the disease. What symptoms do you get if you walk with your foot external?

Hope this helps.
Eric

 

Thanks for taking the time to reply efuller.

I do not believe it is tibial torsion as I have looked at the malleolus axis compared to the knee joint.

I can internally rotate the leg but when I do I notice it is greatly limited in comparison to the left leg. When I do internally rotate it I notice a tightness in the glutes. This leads me to believe it is a soft tissue issue.

I have made a self referral to physio as I hope they may be able to release any soft tissues or advise me on increasing my hip internal rotation.


Could you explain how having a LLD would have an effect on this issue. My right leg (the problematic one) is around 1-2 cm shorter.

[Biomechanics is such a hard subject! Its one of those subjects where I dont even know where to begin!]

 

Are you familiar with the tissue stress approach to biomechanics. For me, it makes biomechanics a lot simpler. In the tissue stress approach, you identify the injured structure and then try and reduce stress on that structure. If you don't know where to begin, you should always begin with what hurts. Which leads to the question of why do you care if your foot is external in gait.

There are so many ways that one can "compensate" for a limb length discrepancy that I don't feel that I can explain anything about the limb length difference without examination. 1-2cm is a quite large difference.

Eric