Understanding and Evaluating Shoes

Key Principles To Evaluating Athletic Footwear

Modern athletic shoes have evolved since the founding of the first sports shoe store in the 1890s. The store was subsequently re-named Reebok in 1958. In 1917, the first popular “sneaker” brand Keds^®and the high top boot Converse All Star^® were introduced. By 1932, the Chuck Taylor name was added and the Converse All Star Chuck Taylor^® became a household name that remains popular today. Reportedly 60 percent of Americans have owned or own these shoes.¹ These key events and developments set the stage for modern athletic shoes.

When it comes to evaluating athletic shoes, it is important to have an understanding of the terminology and technology when communicating with colleagues and patients. Unfortunately, there is no industry standard for any of the current terminology in shoe construction. There is also a lack of standard terminology in regard to placing shoes in their appropriate biomechanical category.

The primary terms and categories of running shoes include motion control, stability and cushioning. Even though these terms are in common use, they have great variation in their application, often no consistency and even contradictory usage among manufacturers. Some companies have even discarded these terms of evaluation in favor of their own “new” terms, like guidance or support.

However, for the purpose of this article, the term motion control shoe will include at least dual density ethylene vinyl acetate (EVA) midsole, midfoot torsion and flexion stability. Stability shoes have these same components but have less torsion and flexion stability than motion control shoes. Cushion shoes have no medial high density EVA, preferably only “mild” midfoot torsion and flexion stability, and therefore are constructed to primarily provide shock absorption.

A Guide To The Four Basic Shoe Components

In addition to understanding basic terminology, one must have both a general and specific knowledge of basic shoe components. Having a strong understanding of the four components of a shoe is critical to evaluate shoes clinically and understand the research that is available. These components are the outsole, midsole, midsole cushioning device(s) and insole.

The different outsoles currently in use are primarily carbon rubber, solid rubber, blown rubber and thermoplastic polyurethane.

• Carbon rubber is used in the plantar lateral heel area to reduce breakdown due to high impact loads at lateral heel strike.

• Solid rubber, either synthetic or natural rubber, is used for a full-length outsole. Solid rubber is very durable and has more shock absorption than carbon rubber.

• Blown rubber is synthetic rubber with tiny air pockets for extra cushioning. Blown rubber is used in the forefoot.

• Thermoplastic polyurethane (TPU) is commonly used in the midfoot of the shoe for structural support.

Midsole materials include ethylene vinyl acetate, polyurethane and combination EVA.

• Ethylene vinyl acetate has good cushioning but less durability than polyurethane.

• Polyurethane, which is often used in the rearfoot with EVA in the forefoot, has high durability but less cushioning than EVA or combination EVA.

• Combination EVA is comprised of EVA and rubber, often around 60 percent EVA and 40 percent rubber. This is often used in higher end shoes to provide greater cushioning, shock absorption and durability in comparison to EVA.

Research has shown the use of stiff midsole materials reduces eversion and eversion excursion.² The technology of integrating higher density EVA in the medial portion of the heel to midfoot remains a hallmark of modern motion control shoes by all manufacturers. This is one of the simple clinical evaluations of shoes a clinician can perform in the office, even if he or she is unfamiliar with specific shoe models. Using this evaluation, the clinician can begin to determine if patients are in the correct shoe for their biomechanics and whether the current shoe is contributing to the injury.

When it comes to midsole cushioning devices, each manufacturer has different technology (air, gel, etc.). When these devices are placed laterally in the shoe’s midsole, they decelerate pronation movements of the rearfoot.³ Clinically, this can reduce injuries, especially in those with excessive pronation, as this deceleration of pronation decreases the force acting upon the soft tissues. These lateral cushioning devices have also played a role in reducing shock-related injuries (such as an uncompensated forefoot valgus or plantarflexed first ray) in the supinated foot.

Finally, there are the inexpensive EVA insoles that are standard within the shoes. However, one can replace even this insole with a custom orthotic or simple over the counter insoles. Research has shown that simple, cushioning, high-quality insoles reduce mean vertical ground reaction force peak, ground reaction force loading rate and peak tibial acceleration.⁴ Therefore, even upgrading the standard insole in shoes can reduce forces on the lower extremity and significantly aid in treating and preventing athletic injuries.

Studies have determined that when these four seemingly simple components are used in motion control shoes, they can control rearfoot motion and attenuate shock in cushioned shoes.⁵ Williams and colleagues found that runners with low arched feet are more likely to sustain soft tissue injuries and those with high arched feet are more likely to have bone injuries such as stress fractures.⁶ We can properly identify these feet and make appropriate shoe recommendations that help reduce or avoid injuries.

In decades of evaluating shoes, I have found consistent features in motion control shoes that can help the clinician evaluate and recommend appropriate shoes. Checking for midfoot torsion stability, midfoot flexion stability and heel counter rigidity, in conjunction with high density EVA medial posting, can help determine the level of motion control that a shoe possesses.

Classically, my clinic divides shoes into four categories: maximum, moderate and mild motion control shoes with the fourth category being neutral/cushion shoes. Even with neutral/cushion shoes, we recommend shoes that have stable midfoot portions as reflected in the torsion and flexion tests. This simple categorization then allows us to assess a patient’s biomechanics and recommend a category of shoe most appropriate for his or her foot. This has consistently allowed us to make accurate recommendations that do in fact reduce injuries. Along the same lines, Knapp and co-workers matched appropriate high arched feet to appropriate shoes to reduce lower extremity and back injuries by 50 percent.⁷

What You Should Know About Lacing And Shoe Uppers

In addition, a look at the upper and lacing of shoes can help in treating and diagnosing foot problems. Running shoe uppers are typically made of mesh with synthetic leather for cosmetics and to reinforce high stress areas. The mesh provides breathability, which dissipates heat and transfers moisture, which can reduce the risk of blisters and fungal infections. The synthetic materials for cosmetics and reinforcements generally do not affect performance. However, the stitching for the reinforcements can cause ridges that irritate the fifth toe or fifth metatarsal head area.

The more common problem is that the reinforced or cosmetic material causes an irritation at the forefoot flex point in the shoe with secondary skin and sometimes joint irritation. We have been known to use a scalpel to cut out a layer of synthetic material to leave only the mesh so there is no irritation. Sometimes this is difficult to do to a $120 running shoe.

Finally, lacing irritation due to the tongue pad being too thin can cause irritation to the dorsal nerves. Changing the lacing by “skipping” this area, generally over the first metatarsocuneiform joint, or adding additional tongue padding will generally cure this nerve irritation.

Pertinent Pointers On Walking Shoes And Cross-Training Shoes

For a small sampling of shoes and brands we commonly recommend for the aforementioned categories we utilize, see “What You Can Recommend For Motion Control And Neutral/Cushion Shoes” below. Our complete list is much more comprehensive and lengthy than this article will allow. We then match the patient’s evaluated foot type to the appropriate shoe category.

Walking shoes. Typically, running shoes are the best recommendation for walking. Running shoes offer specific biomechanical categories, a complete range of shoe widths (AA to EEEE, depending on the brand), last shapes (straight, semi-straight, slightly curved and curved) and are readily available in most markets. One can utilize a more traditional walking shoe with a leather upper. However, there are no biomechanical categories to match different foot types and limited choices in last shapes to match foot shapes.

Cross-trainers. This shoe category has been weak in both its availability in various models and consistency in models from year to year. We almost exclusively recommend that patients use specific “tennis” shoe brands and models as opposed to shoes that are marketed as cross-training shoes. These shoes offer all the needed features of a cross trainer for jumping, side-to-side movement and cushioning that a traditional cross-trainer needs. However, tennis shoes also offer a great deal of consistency year-to-year, excellent durability (some with guarantees for length of wear) and up-to-date technology to meet the demands of amateur and professional tennis players.

Essential Insights On Rocker Bottom Shoes

Rocker bottom. Midfoot and/or forefoot rocker bottom shoes include negative heels or solid ankle cushion heel (SACH) heels. This new category of mass market shoes previously was only available through custom shoe modification.

The MBT^® (Masai Group International) features a SACH heel concept with a midfoot and forefoot rocker bottom. This is the most well known rocker bottom shoe and is credited with starting this new wave of popular shoes.

Shape-ups^® (Skechers) include a SACH heel concept that extends into the midfoot with a midfoot and forefoot rocker bottom. This provides more cushioning but is more unstable in the frontal plane. This shoe is the most heavily marketed and readily available at local stores.

Chung Shi shoes (Foot Solutions) feature a negative heel concept with a midfoot rocker bottom and less rigid forefoot rocker bottom. These are limited in their availability.

Cogent shoes (Cogent Motion) feature a negative heel concept with a midfoot rocker bottom and a less rigid forefoot rocker bottom. These are becoming more readily available but also have the greatest midfoot “flat spot,” which has offered some benefits for prolonged standing but sometimes less comfort with walking.

There are many other upcoming rocker bottom shoes with a new brand available almost monthly, making it difficult to keep up on the brands and availability at this time.

The primary medical indications for these styles of shoes are ankle arthritis, midfoot arthritis, hallux rigidus and chronic forefoot metatarsalgia. Contraindications or at least areas of significant concern are instability, diminished general proprioception (as in elderly patients), equinus or a history of Achilles tendinopathy.

When Patients Have To Stand For Prolonged Periods Of Time

Prolonged standing activities. Dansko^® Professional Clogs (Dansko) have been the mainstay of shoes for prolonged standing. The unique last of this shoe redistributes load off the forefoot, into the arch and heel, with standing. As the patient walks, the stiff forefoot rocker decreases range of motion demands on the metatarsophalangeal joints. These shoes work well with hallux rigidus, midfoot arthritis, metatarsalgia, capsulitis and bunion pain. Contraindications or at least areas of significant concern are instability and diminished general proprioception (as in elderly patients). Patients would utilize these shoes primarily for prolonged standing and they can function better than any other shoe.

In Conclusion

Although podiatrists are experts in the foot and ankle, we cannot truly be experts unless we understand shoes. That understanding must include a basic knowledge of design features, specific technologies that have proven effective and at least a basic familiarity with selecting appropriate shoes to match a patient’s biomechanics and specific foot problem. Anything less than this will cause a partial and at times complete failure in the treatment of patients with foot, ankle and even knee-related problems.

Five Myths About Foot Care

Old wives tales and myths like that example are fun to laugh at. We believed them as children. Step on a crack and youb’ll break your mother’s back.But there are other myths that are no laughing matter, especially when they involve your health.

Myth: Cutting a notch in a toenail will relieve the pain of ingrown toenails.

Reality: When a toenail is ingrown, the nail curves downward and grows into the skin. Cutting a notch in the toenail does not affect its growth. New nail growth will continue to curve downward. Cutting a notch may actually cause more problems and is painful in many cases.

Myth: My foot or ankle can’t be broken if I can walk on it.

Reality: It’s entirely possible to walk on a foot or ankle with a broken bone. It depends on your threshold for pain, as well as the severity of the injury, says Dr. Campitelli. But it’s not a smart idea. Walking with a broken bone can cause further damage.

It is crucial to stay off an injured foot until diagnosis by a foot and ankle surgeon. Until then, apply ice and elevate the foot to reduce pain.

Myth: Shoes cause bunions.

Reality: Bunions are most often caused by an inherited faulty mechanical structure of the foot. It is not the bunion itself that is inherited, but certain foot types make a person prone to developing a bunion. While wearing shoes that crowd the toes together can, over time, make bunions more painful, shoes themselves do not cause bunions.

Although some treatments can ease the pain of bunions, only surgery can correct the deformity.

Myth: A doctor can’t fix a broken toe.

Reality: Nineteen of the 26 bones in the foot are toe bones.

What I tell patients is, there are things we can do to make a broken toe heal better and prevent problems later on, like arthritis or toe deformities, Dr. Campitelli says.

Broken toes that aren’t treated correctly can also make walking and wearing shoes difficult. A foot and ankle surgeon will x-ray the toe to learn more about the fracture. If the broken toe is out of alignment, the surgeon may have to insert a pin, screw or plate to reposition the bone.

Myth: Corns have roots.

Reality: A corn is a small build-up of skin caused by friction. Dr. Campitelli says many corns result from a hammertoe deformity, where the toe knuckle rubs against the shoe. The only way to eliminate these corns is to surgically correct the hammertoe condition.

Unlike a callus, a corn has a central core of hard material. But corns do not have roots. Attempting to cut off a corn or applying medicated corn pads can lead to serious infection or even amputation. A foot and ankle surgeon can safely evaluate and treat corns and the conditions contributing to them

Wearing Flip-Flops? Watch Your Step

August 4, 2010

They're everywhere when the weather turns warm, but a podiatrist warns flip-flops carry more risks than blisters and stubbed toes.

Dr. Rock Positano, the director of the Non-surgical Foot and Ankle Service at the Hospital for Special Surgery in New York City, says the risk is not that people wear flip-flops — it's how they wear them.

"I have no objection when patients say, '... What is the best way to wear these type of shoes?' I always say, 'Look, use your head — if you're hanging out by the swimming pool or hanging out on the beach, they really cause no damage or no problem,'" Positano tells NPR's Michele Norris. "When people develop problems is when they wear them in an unusual situation — such as 5-mile hikes or standing on their feet for 5 to 10 hours on a trip."

Positano says that's when he sees tendinitis, heel problems, Achilles tendon issues, ankle injuries — as well as injuries in other parts of the body.

"Unfortunately, these shoes have no significant orthopedic support for the foot and the ankle. And of course, as Leonardo da Vinci taught us, the foot and ankle is the most important part of the body cause it makes contact with the body first. If the shock is not absorbed appropriately from the ground — it gets transmitted to other parts of the body. So what'll happen — it'll start as a foot issue, and then it will go to the lower leg, the hip, the knee, the back," he says.

Positano also says beware of wearing flip-flops in areas where there might be a higher concentration of pathogens or bacteria.

"We see that particularly in Central Park," he says. "I had a patient a few years ago that developed one of the nastiest, nastiest skin infections I've ever seen — required the person to be on antibiotics for almost two months. And the reason being was that this was a person that was wearing an exposed shoe."

If you're going to wear flip-flips, Positano advises wearing flip-flops with thicker soles.

"I prefer a thicker one, because it's more rigid. And of course the rigidity gives the person a little bit more support, which means they have better capability for shock absorbing. And people also ask this question: 'The cave man used to walk [on] bare feet.' I say, 'Yeah, but the problem is the cave man only lived to 20 years old.' I mean, people are living a lot longer lives these days and you need to be able to protect your feet from an earlier onset. Because clearly the problems you have now are only going to get worse as a person ages."

Melanomas. Stay out of tanning beds....

Melanomas do occur in the foot. The following pictures are patients of mine where melan

omas were diagnosed. The image between the toes was discovered early enough to be treated with primary excision and was considered cured. The second image was obviously too far advanced when they presented to me. If you see moles or discolored lesions on your feet, or any areas of your body, watch them closely. Follow the ABCD's:

A: Asymmetry. If you draw a line through the mole it should look the same on both sides.

B: Borders. The borders should be smooth and regular.

C: Color. The color should be one color and uniform.

D: Diameter. No larger then a pencil eraser.

There is variance in these rules and melanomas can occur in moles that do not fall into this category. If a new mole appears on a non sun exposed area, it is worth having it examined. When in doubt we always biopsy them as early detection is the best and easiest treatment.

See this article published in the USA today regarding a rise in melanomas from tanning beds.

Severs Disease

Well, it's not really a disease, but a condition. Severs disease is the condition that describes pain to the "back part" of the heel that typically occurs in children between the ages of 10 to 14. In this area is a growth plate that can become inflamed with increased activity or from a sudden force, such as jumping off a couch or bed. Many times the ER will refer me a patient with the a diagnosis of a "fractured heel" because this growth plate appears very irregular as it is fusing with the heel bone during development. Sometimes during a "growth spurt" the muscles and tendons can't stretch as fast as the bones are growing and the increased tension will produce this pain. Rest, stretching, and anti-inflammatories usually will improve symptoms, while a cast and crutches will help for those with pain lasting several weeks to months. Yes, you could call this growing pains!!

Blisters

Should I puncture this blister? This question is frequently asked by patients and runners. It is always best to have a physician make the ultimate decision, but a majority of blisters can be released to allow the fluid to drain and lead to a faster and less painful recovery. A blister is secondary to friction which disrupts the layers of skin allowing fluid to accumulate. When access fluid is present and the skin is unable to stretch, this can become very painful. Using a sterile instrument such as manicure scissors, or even a needle (always wipe with alcohol) the blister can be broken allowing the fluid to drain from a gravity dependent area on the blister. Blisters can also result from fractures or even peripheral vascular disease. These are medical emergencies and require immediate attention.

Extra Digits

Extra Digits

Also known as Polydactyly, extra digits are the most common congenital digital anomaly of the hand and foot. It may appear in isolation or in association with other birth defects. Isolated polydactyly is often autosomal dominant or occasionally random, while syndromic polydactyly is commonly autosomal recessive.

The condition is usually asymptomatic, but can sometimes lead to a painful lesion between the toes, or in the below case, a painful deformed nail was the result. After 40 years of discomfort, the patient finally elected to remove the nail. Eventually we will remodel toe to prevent pain from occurring in between the great toe and the 2nd toe. The "Webbed" toes that are seen are non symptomatic and I usually advise not surgically correcting if pain is not present.

Frequently Asked Questions About Bunion Surgery

1. Are bunions hereditary?

Bunions are most often caused by an inherited faulty mechanic structure of the foot. It is not the bunion itself that is inherited, but certain foot types that make a person prone to developing a bunion.

2. Do over-the-counter pads and splints really work?

Pads placed over the area of the bunion may help minimize pain from a bunion. However, padding and splinting cannot reverse a bunion deformity.

3. Will my bunion get worse?

Because bunions are progressive, they don't go away, and will usually get worse over time. But not all cases are alike. Some bunions progress more rapidly than others.

4. Is it better to have it fixed now, or should I wait?

When the pain of a bunion interferes with daily activities, it's time to discuss surgical options with your foot and ankle surgeon. Together you can decide if surgery is best for you.

5. How can I avoid surgery?

Sometimes observation of the bunion is all that's needed. A periodic office evaluation and x-ray examination can determine if your bunion deformity is advancing, thereby reducing your chance of irreversible damage to the joint. In many other cases, however, some type of treatment is needed, such as changes in shoes, padding, activity modifications, pain medications, icing, injection therapy, and orthotic devices.

When the pain of a bunion interferes with daily activities, it's time to discuss surgical options with your foot and ankle surgeon. Together you can decide if surgery is best for you.

6. Will my insurance company pay for the surgery?

In most cases, yes.

7. Is the surgery painful?

The amount of pain experienced after bunion surgery is different from one person to the next. Most patients will experience discomfort for three to five days. If you closely follow your foot and ankle surgeon's instructions, you can help minimize pain and swelling after your bunion surgery.

8. What type of anesthesia is involved?

Most bunion surgeries involve local anesthesia with intravenous sedation. That means your foot will be numb and you will be given medications to relax you during the procedure.

9. If I need surgery, how long will recovery take?

The length of the recovery period will vary, depending on the procedure or procedures performed. Your foot and ankle surgeon will provide you with detailed information about your recovery.

10. Will I be able to walk normally, or even exercise and run, after healing from bunion surgery?

In most cases, yes.

11. How soon can I walk after surgery?

It depends on your bunion and the surgical procedure selected for you.

12. How soon can I go back to work after surgery?

The length of the recovery period will vary, depending on the procedure or procedures performed.

13. How soon can I drive after surgery?

The length of the recovery period will vary, depending on the procedure or procedures performed.

14. Can the bunion come back?

Yes, there is a risk for bunion recurrence in some cases. Patients can help prevent this by following their doctor's instructions to wear arch supports or orthotics in their shoe.

15. If screws or plates are implanted in my foot to correct my bunion, will they set off metal detectors?

Not usually. It can depend on the device chosen for your procedure, as well as how sensitive the metal detectors are.