Highly Flexible & Severe Over-Pronators

The Ultimate Support Challenge

Functional foot types, like any biological phenomenon, follows a roughly bell-shaped curve pattern: the vast majority of people will be in flexible, moderately over-pronating middle; those with highly flexible and severely over-pronating feet will be towards one end of the spectrum; very rigid feet at the other end. Orthotic support is potentially helpful to all but the most rigid feet, because some degree of flexibility is necessary to change foot posture and function with an orthotic.

While those in the deep blue, left-most part of the curve stand to gain the most from Sole Supports, the more extreme cases will often need additional design elements to prevent progressive shell collapse or the tendency for very flexible feet to slide away from support. They are, in order of aggressiveness:

1) Using a deep heel cup
2) Checking the “Heavy Duty Use” box in section three of the Design Form
3) Specifying a High Medial Flange
4) Specifying an additional increase in shell thickness

A deep heel cup provides more surface area around the heel for better control of calcaneal inversion. It also adds more plastic to the medial transition from heel to arch which bolsters at least proximal arch stability. This is the area where most patients are aware of the control pressure from the orthotic from underneath the sustentaculum tali

Colored shell area approximates the extra plastic wall provided by a high, medial flange.

Over and above the first three design reinforcements Highly Flexible & Severe Over-Pronators The Ultimate Support Challenge Calf stretching is an important adjunct routine to orthotic intervention. Highly FlexibleSevere Over-PronationBluer Areas = More Likely To Benefit From Sole SupportsIncidence in PopulationHighly RigidSevere Over-Supinationor Over-PronationNormal Colored shell area approximates the extra plastic wall provided by a high, medial flange. 2 is the option to specify a certain additional thickness in the shell. This can be an effective option for the “ultimate” flexible over-pronator, especially when that patient has a history of flattening less robust shells. For the experienced Sole Supports practitioner who has successfully used this modification with past cases, this option can be ordered for first-time patients with some confidence. After all, the worst case scenario is that the shell is too rigid and needs some grinding for more flex. If you have not had experience with ordering extra shell thickness, we advise you to consult about your case with our tech support department.


Calf stretching is an important adjunct routine to orthotic intervention.

“Heavy Duty Use” adds a percentage increase to shell thickness based primarily on routine activities such as long distance running, heavy lifting and prolonged standing.

A “High Medial Flange” is an extra lip of plastic off the medial side of a deep heel cup extending into the medial proximal arch (see the pages on “Assessing Flexibility” for more details). This does not appear as a standard option on our design forms because we advise our practitioners to consult with our tech support to insure the applicability to a particular case. This further enhances proximal arch stability while also providing some laterally directed force against the highly flexible foot with medial splay.

On occasion we have had inquiries concerning cases where the hyper-flexibility extends into the ankle joint. In such cases the patient may be observed to be literally walking on the medial sides of their feet due to the excessive laxity at the talocrural joint. This is a situation that transcends mere foot collapse. Our most common recommendation is to utilize a slim profile ankle brace that will fit into the patient’s shoes and support against excessive ankle motion medial or lateral. With that stabilized, the patient should be able to use Sole Supports for control of the foot.

It should be noted that the most accurate possible cast, which does not flatten the medial or longitudinal arches during casting and captures a well-supinated posture of the foot, is the primary factor in controlling the hyper-flexible foot. Such a cast captures the most custom contour possible for a maximum surface area, nested control of the foot posture that will help prevent lateral sliding of the foot off the support.
The type of shoe used is also important. A very flexible foot will benefit from a firm heel counter and midshank. The lateral side of the shoe should be firm as well as this is where the foot will tend to slide into to get off the orthotic support. A good test of overall shoe support is to grab by the heel with one hand and the toebox with the other. Try to twist the shoe to get a sense on how stiffly the shoe resists deformation. To give an example of a shoe with very good stiffness and motion control, try this test on a Brooks Beast running shoe.