Pronation Part VII – How to Address Pronation II – Casting for Orthotics

As mentioned in our last post, many pairs of orthotics are made incorrectly and don’t address the main issue with pronation. Properly made orthotics must have support for the ball of the foot in order to properly address one’s pronation and the issues caused by it. If you haven’t already, go check out our previous pronation posts to get the relevant background information for this post!

Most issues with incorrectly-made orthotics can be traced back to the casting method—i.e., the method used to create the molds of the feet (which are then used to make orthotics). Many methods involve someone stepping into impression molds or onto pressure plates. The problem with this is that the individual is in a weight bearing position, which completely misses the reason behind pronation.

We cannot stress enough that pronation occurs because the ball of the foot must come down to the ground when weight bearing. Therefore, methods requiring someone to be in a weight bearing position will not result in accurate molds of the feet, as they won’t be in a subtalar neutral position. Proper casting methods require people to be in non-weight bearing positions in order to make orthotics properly. That said, many methods involving sitting positions also tend not to result in accurate foot molds: they often rely on active/passive dorsiflexion of the foot to hold the “neutral position” without accounting for the side-to-side rotation that occurs with pronation.

In our clinic, casting is done in a prone (lying face down) position. That way, the feet aren’t loaded and can be properly set (and held) in subtalar neutral while the casts are made. As seen in the video below, strips of plaster are used to encase the feet, which are held in subtalar neutral as the plaster sets. Based off of these molds, the orthotics will then be made with the proper amount of support to keep the ankle in subtalar neutral.

Pronation Part VII – How to address pronation – casting

One last, but very important, thing to remember about orthotics: since pronation is important for shock absorption, orthotics should still allow for some pronation to help with shock absorption, but not so much that the foot is constantly thrown out of neutral alignment.

Pronation Part VI – How to Address Pronation I – Orthotics

When people pronate, they’re often told to strengthen the foot muscles to “build an arch” that sets the foot in a neutral position. However, this assumes that pronation is the same as flat feet, which it is NOT. If you haven’t already, check out our previous pronation posts to get up to speed!

Remember, the issue with pronation is not with the arch, but with forefoot varus when the ankle is in subtalar neutral and the ball of the foot coming down to the ground when weight bearing. Therefore, training the muscles to create an arch helps minimally, as someone with forefoot varus will still pronate when the ball of the foot comes down. Even if the foot muscles can build an arch approximating subtalar neutral and are trained, they cannot maintain it 24-7: muscles eventually fatigue, causing the foot to pronate and the arch to collapse again—when dynamic movement is incorporated, that arch is even more likely to be lost.

So what corrects for pronation? The answer is orthotics: custom insoles made to keep the foot in a subtalar neutral position. This is achieved by supporting both the arch and the ball of the foot, such that it no longer drops when weight bearing—something that cannot be compensated for with foot musculature OR an arch support alone (pronation is a structural issue).

Many orthoses are actually just arch supports, but these don’t help much and may actually make the problem worse! Without support underneath the ball of the foot to maintain the forefoot varus position, pronation still occurs when weight bearing: the foot rolls over the arch support, which can further exacerbate one’s problems. Imagine shoving a rock underneath your foot and walking on it all day!

As seen in the photo, a pronated foot [1] still pronates on an orthotic that’s just arch support [2] because the ball of the foot is unsupported. However, with the properly made orthotics [3], the ball of the foot is supported so the foot no longer pronates and can maintain a subtalar neutral position. That said, there are some (rare) cases of calcaneal or midfoot instability (WITHOUT forefoot varus) that do benefit from arch supports alone. It all depends on the foot structure!

Pronation Part V – How Pronation Affects Low Extremity Movement II – Knee Flexion

Pronation 5_how pronation affects lower extremity movement_knee flexion

When the foot pronates and knee is rotated internally, any movement that requires flexion (bending) will occur at an oblique angle, as seen in the video above (the pronated foot is shown on the left, while the corrected foot is shown on the right). In other words, the knee does not move directly over the ankle, but rather off to the medial side (towards the midline of the body). Due to this oblique angle, people who pronate tend to excessively torque the knee—the degree of which depends on the degree of pronation. This puts additional strain on the anterior (front) and medial aspects of the knee, which may not be a significant issue when it comes to everyday activities such as walking, but it plays a huge factor in exercise and athletic performance.

Due to the additional torque on the knee caused by pronation, athletes in sports that involve explosive, rotational, and lateral movements—on top of rapid changes in direction—may be more prone to injuries. Since some individuals (particularly the young and/or fit crowd) may be able to compensate for their pronation, not necessarily everyone who pronates will experience symptoms of pain. However, regardless of injuries and/or pain, pronation can certainly affect athletic performance.

Having a “corrected” foot placed as close to subtalar neutral allows the knee and ankle to track properly, which translates to the optimal movement mechanics, as no energy is wasted in generating power. This significantly affects athletic performance, even in absence of injuries. When the knee doesn’t tract properly, more force is required to generate the same power and control the movement. This further exacerbates any issues caused by one’s pronation and can contribute to hip and knee stability. When the ankle and knee are properly aligned, the body is able to properly stabilize these structures and move more efficiently.

Pronation Part IV – How Pronation Affects Lower Extremity Movement I – Gait

In our first post regarding pronation, we discussed how pronation affects static posture. Today we’ll discuss how pronation affects dynamic movement, particularly the lower extremities. As the foot pronates and the midfoot rotates medially (inward), the knee also rotates internally. This alone may not seem like a big deal when dealing strictly with posture, but the real damage is occurs during movement.

When people pronate they tend to stand with their feet pointed outwards due to their internally rotated knees. In order to stand in a way that takes stress off the knees, the feet must point outward: if the feet are parallel, the knees will be at an oblique angle towards the midline, which is uncomfortable for most people. Therefore, to keep the knees pointing straight forward, the toes must turn out.

Pronation 4_how pronation affects lower extremity movement_gait

As a result, people who pronate tend to roll around the ball of the foot instead of rolling through it when they walk. As seen in the video, the pronated foot begins to roll inward (during the mid-stance phase of the gait cycle) before the heel leaves the ground, whereas the corrected foot remains stable. As the foot remains stable at the ankle and midfoot, it can then move through the ball of the foot instead of rolling around it (during the heel-off phase of the gait cycle). Due to this change in gait a person can develop any combination of the following issues: bunions, plantar fasciitis, neuromas, Achilles tendonitis, lateral ankle pain, knee pain, IT band or piriformis syndrome, low back or neck pain and poor posture and balance.

Pronation Part III – Pronation is not the same as flat feet

In our previous post, we discussed what subtalar neutral and forefoot varus are and how they play a key role in determining whether someone pronates—go check it out if you haven’t seen it yet! This post will elaborate on that and focus on the difference between pronation and flat feet.

In the previous post, there is a visible (albeit relatively low) arch when the foot is placed in subtalar neutral. However, that arch disappears when the ball of the foot comes down to the ground and the foot relaxes. Similarly, one could have an arch when the foot is non-weight bearing but becomes flat when weight bearing. In the video below, the foot has a visible arch when lifted off the ground, but again, disappears as soon as it’s lowered and the ball of the foot comes down. Notice how in both anterior and medial views, the lateral (outer) side of the foot hits the ground first—this is indicative of forefoot varus!

Pronation 3_Pronation is not flat feet II

 

Looking at the arch in non-weight bearing positions and weight bearing positions can sometimes offer some insight as to whether you pronate or truly have flat feet. If you have an arch (regardless of how high or low it is) when non-weight bearing but your foot flattens out when weight bearing, then you pronate. And if your foot is flat in both scenarios, then you truly have flat feet. However, the only way to truly tell whether you pronate or flat feet is to put the ankle in subtalar neutral and assess whether there is forefoot varus.

For example, if the ankle is in subtalar neutral and an arch (regardless of height) forms but the person has forefoot varus, then they do not have actually flat feet—they simply pronate. However, if the foot does not exhibit forefoot varus in subtalar neutral and does not create an arch, then the person doesn’t pronated and truly does have flat feet.

 

Key takeaways:

Since the position of the feet in subtalar neutral determines the degree of pronation, the arch collapsing is not the real reason why people pronate. It’s simply an effect due to forefoot varus and therefore, an arch support is not the key to fixing your pronation issues!