Ode to the Popliteus

Remember the popliteus? To recap, it contracts at the initial contact phase of the walking gait cycle, to act as an accessory PCL (look HERE

https://www.thegaitguys.com/search?q=popliteus&f_collectionId=57d4982c91b18610c6ee3e0f

to read about that), then contracts eccentrically to slow the rate of internal rotation of the femur on the tibia until midstance, so as not to macerate the meniscus; It then contracts concentrically to accelerate the external rotation of the femur on the tibial plateau so it rotates faster then the tibia, to protect the meniscus as well. So, internal rotation of the femorotibial complex from initial contact to midstance and external rotation of the complex from midstance to preswing. Got it?

Now look at the video of this gal with L sided medial knee pain and past history of a left tibial plateau fracture in her youth. Do you see it? Hmmmm; doesn’t look like internal rotation does it? Don’t see it? Remember that the whole complex SHOULD be internally rotating until the swing phase leg passes the stance pase leg. See it now? Considering that the popliteus tested weak on the clinical exam, does this surprise you?

Agreed that there are many factors initiating internal rotation (and thus pronation) of the stance phase leg from initial contact to midstance, like plantar flexion, adduction and eversion of the talus, contraction of the lower leg anterior compartment muscles, eccentric contraction of the quads and hamstrings, just to name a few, can you see how (a least theoretically) one bad player can ruin the team?

Yes, popliteus rehab, along with abdominal core and foot core endurance exercises are in her future.

Dr Ivo Waerlop, one of The Gait Guys

#popliteus #kneepain #kneeproblem #thegaitguys #gaitanalysis

The Adductor Magnus; Not just for adduction anymore...

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Yet another paper (1) to support the notion that the adductors (particularly the adductor magnus, in this paper), act as external rotators (especially eccentrically), not internal rotators as is commonly purported in many anatomy texts (2) . Remember that the lower extremity is internally rotating (as a whole) from initial contact to midstance and externally rotating from midstance to pre swing. SOMETHING needs to help attenuate some of that internal rotation (and pronation) that occurs during the 1st part of stance phase and assist in external rotation (and supination); now you can add the adductor magnus to the popliteus, deep six external rotators, anterior and posterior compartments of the lower leg to the hamstrings and quads.

"This study suggests that adductor magnus has at least two functionally unique regions. Differences were most evident during rotation. The different direction-specific actions may imply that each segment performs separate roles in hip stability and movement. These findings may have implications on injury prevention and rehabilitation for adductor-related groin injuries, hamstring strain injury and hip pathology."

 

1. Benn ML, Pizzari T, Rath L, Tucker K, Semciw AI1 . Adductor magnus: An emg investigation into proximal and distal portions and direction specific action. Clin Anat. 2018 Mar 9. doi: 10.1002/ca.23068. [Epub ahead of print]

2. Leighton RD. A functional model to describe the action of the adductor muscles at the hip in the transverse plane.Physiother Theory Pract. 2006 Nov;22(5):251-62.



 

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