By Gavin Buehler
In the previous two articles of this series, we touched upon two factors that might influence tibial rotation and have an impact on knee alignment resulting in knee discomfort. We looked at what roll the hamstrings could play, as well as the glutes. In this article we’ll wrap up with the core. Please remember that these highlighted factors are just a few possibilities that could affect knee discomfort and may not apply to your individual case. It is always recommended that you consult with your healthcare professional for a proper assessment.
In the last post, an external tibial rotation or appearance of could have been the result of the femur (thigh bone) sitting internally rotated on the tibia (shin bone) giving the appearance of the tibia being in external rotation. This presentation may come from a glute or hip imbalance as we discussed. But sometimes we find the femur sitting in a good neutral position, yet the tibia presents with an external rotation and the hamstrings don’t appear to be the main contributing factor. In this scenario we explore some other possibilities that could be a root cause.
In my practice I have found the abdominal obliques to commonly have an imbalance or dysfunction affecting many things including tibial rotation.
How can an imbalance in the core affect the shin?
To understand the relationship between the core and shin, we must consider the fascial system and how it connects everything in our bodies as a unit. I’ve previously posted two articles that go into more detail if you would like to reference those for a more complete perspective. The video included below in this article may also help, but for this post I’ll highlight the Spiral Fascial Line as it has the most influence on what we’re discussing since the abdominal oblique muscles function within it.
The Spiral Line
The Spiral Line is a continuous fascial sling that loops around the body from head to foot resembling a helix or “spiral” crossing from one side of the body and then back to the other. The body has two of these slings, one for each side. These tension bands wrap the body to assist in maintaining structural balance across all planes. Due to its connections between the pelvis and foot arches, the integrity of these bands plays a role in effective knee-tracking, among other things, when performing basic daily activities such as walking. An imbalance between these lines can cause rotational and lateral support issues causing the body to lapse into an offset postural pattern feeding into compensatory patterns increasing the risk of injury.
Contributing to the stability of these tracts are the muscles that lie throughout them. Beginning at the occipital ridge/mastoid process of the skull, these bands travel down the back of the neck through the splenius capitis and cervices muscles, crossing over to the opposite side rhomboids, wrapping around the ribcage through the serratus anterior, knitting into the external abdominal obliques, travelling down diagonally across the abdomen to the internal obliques, continuing through the tensor fascia latae and iliotibial tract (IT Band) along the lateral thigh. For our discussion a key attachment point occurs here at the lateral condyle of the tibia, and into the tibialis anterior crossing over the front of the shin to the inside of the foot before looping underneath it helping to support the longitudinal arches. It then travels back up the outside of the leg along the fibularis longus where it moves into the biceps femoris (lateral hamstring) going up the back of the thigh towards the sacrum into the sacrotuberous ligament and sacrolumbar fascia connecting into the erector spinae muscles returning up to the occipital ridge again.
The connection and effect
Having mapped out this line, we can see a clearer picture of how the core connects to the shin. Keep in mind that an imbalance or dysfunction anywhere within this chain could potentially affect tibial alignment. The reason why I’m focusing on the abdominal obliques is because that is the most common area that I find a weakness or imbalance between sides in these lines.
With the visual of these lines we can see that if there is an imbalance between the tensions of these two slings a rotation and lateral shifting can easily occur causing a favoring to one side. If the portion of the sling containing the abdominal obliques is weak or slack, other sections of the line need to take up that slack since it is a continuous loop. If we think of a rubber band looping around something, the areas that generally hold the most tension are the points where there is a sharp change in direction. Looking at our bodies, when there is a slack through the internal obliques near the hip, besides that causing a pelvic rotation and/or lateral hip glide that will directly affect knee alignment, the tension areas in the sling that become tighter are the muscles before and after one of the farthest points of the loop around the foot. The tibialis anterior and fibularis longus. These muscles are almost always hypertonic (tight) and tender on patients presenting with this pattern. As a result, the excessive tension cradling the shin and foot can rotate the tibia along with the help of unbalanced weight bearing due to the compensations occurring at the hip.
The external obliques on the opposite side of the body may also be weak, but I find that if they are the focal point of the slack in the chain, shoulder and neck discomforts tend to be the prevalent complaint. That is a whole other can of worms that we won’t dive into here.
How can we balance/strengthen the abdominal obliques?
There are many different exercises that can be performed to aid in the balancing and strengthening of these muscles. Here is a link to one of my favourite movements to help curb this issue. It addresses the both the internal and external obliques and the spiral line as a unit.
As always, I hope that you found this article helpful. Please consult a health professional before attempting new suggestions or exercises as each individual presents their own unique case.
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