What causes plantar fasciitis, bunions and Morton’s neuroma?

The most common foot injuries physical therapist see at their clinic is plantar fasciitis, bunions and Morton’s neuroma. In today’s blog we will learn more about them and how they are all connected by one cause. But first let’s have a look to the anatomy of the foot.

The plantar fascia:

The Plantar aponeurosis is the modification of Deep fascia, which covers the sole. It is a thick connective tissue. It is thick centrally, known as aponeurosis and is thin along the sides. It consists of three parts, medial, lateral and the central part, respectively. It is designed to provide support like a shock absorber for the main arch of the foot (called the medial longitudinal arch) when weight bearing.

The plantar fasciitis is similar to a rubber band. When resting the band Is loose and the foot mobile. When you put your foot and the ground, when you walk, run or whatever else, this band is suddenly pulled in both directions and a stiffness effect is created directly.

This stiffness effect is crucial for two main reasons.

• helps the foot maintaining its arch, which in its turn control the degree and the timing of movement from supination into pronation during the stance phase of walking and running.
• transform the foot into a rigid platform that allows the body to push and to propel itself forward.

The majority of people who are diagnosed with plantar fasciitis have pain on the bottom of their foot. That is especially aggravating when taking their first few steps in the morning. The most common description we hear from our patients is, “A knife stabbing the bottom of the foot with each step.”

While these symptoms may lesson briefly during the day, they are often made worse with loading. This means the longer you stand, walk, run, the worse the pain becomes.

For decades, the first step to treating plantar fasciitis was focusing on decreasing inflammation by applying ice, taking pills and complete rest. When this didn’t work, orthotics was prescribed to help support the arch of the foot and by so limiting the excessive pronation along with physical therapy which usually consist of stretching and strengthening exercises for the foot muscles.

Again, when all these are unsuccessful corticosteroids would be injected and rarely surgery may become recommended.

Sadly saying, these methods don’t work for a lot of people where around 50% of those diagnosed with plantar fasciitis still have pain 15 years later.

Fortunately, our understanding for this injury changed in 2003 due to DR. Harvey Lemont. He did an experiment where he took fifty of his patients with severe plantar fasciitis and didn’t improve with the mentioned treatment at the time, and performed a biopsy of the plantar fascial ligament. What he found shocked the medical word.

He didn’t find inflammation in all fifty biopsies!!

He actually found dead cells, called necrotic tissue. For many years therapist assume that this was a plantar fasciitis. Dr. Lemont recommend to change its name from “it is” to “osis”

Plantar fasciosis, characterized by microtears and necrosis of plantar fascia.

 “How does a relatively healthy person get a piece of dead tissue in their foot?” 

Yes, it’s confusing, a person who develop heel pain do not show any circulation problem in their feet first. Usually, the skin appears healthy and intact.

Dr. Ray McClanahan who is trained by Dr Lemont explained the fact that placing our healthy foot into a narrow toe box shoe is the beginning of the problem.

When your big toe is pulled inward, or in adduction motion, a small muscle called abductor hallucis is put in a stretch position which will lead over the time to a pinching of a nearby artery that goes underneath called the lateral plantar artery and will cause blood flow restriction in a very specific part in the bottom of the foot in most of cases.

A group of researchers documented this phenomenon in 2019 in a study, where they positioned their participant’s big toe into a narrow toe box and they measured the blood flow into the foot.

The blood flow was dropped by 60% through the lateral plantar artery, and some people were able to make up for the initial decrease in circulation and return to normal level. which will lead to poor recovery from the stress put.

If we look specifically at the foot, the plantar fascia is placed under stress anytime you are weight bearing simply by walking or running… so remaining bearfoot will maintain healthy feet and will decrease the risk of having plantar fasciosis.

However, those who restrict the blood flow by wearing a narrow toe box shoe are unable to replenish and regenerate this tissue. These tissues on the inside of the heal that are supplied by the plantar artery will begin to degrade and the pain will begin to set in.

Therefore, the bunions and the plantar fascia pain are related.

Next comes the pain in the forefront of the foot, the Morton’s neuroma.

A Morton’s neuroma is a painful enlargement of a small nerve in your foot that runs between the third and fourth toes. Usually, it appears in female over the age of 30 and directly related to footwear.

Many problems feature of modern shoes and contribute to nerve irritation.

Elevated heel: will force the toes into an extended position, which increases exposure to the nerve and therefore the amount of load on the nerve a you stand and walk.

Toe spring: lifting the toes increases the load on the exposed nerve to an even greater degree and adds additional stretch.

Narrow toe box: pushes the bones of the foot together leading to a pinching of the small nerve that runs between the third and fourth toes.

The all above mentioned problem are perfect combination for nerve irritation.

So next time you walk into a shopping mall to buy a brand-new shoe, keep what you have just read in mind.

Here is another link about morton’s neurona:

https://www.mayoclinic.org/diseases-conditions/mortons-neuroma/symptoms-causes/syc-20351935#:~:text=Morton’s%20neuroma%20involves%20a%20thickening,numbness%20in%20the%20affected%20toes.

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