Pace Setter : September 2018

Morton's Neuroma

by Russ Ebbets, DC

Most people’s feet are very sensitive, especially if you are used to wearing shoes all day long. If you had a small stone or some other piece of grit in your shoe not much larger than this letter “o” there is little doubt you’d feel the obstruction. Even the cloth pill of an old sock may present enough of an irritation that a problem soon follows, like a small blister that left untreated can lead to other, seemingly unrelated problems.

The body reacts to these abnormal stresses by thickening the area under stress forming a callous. Manual laborers develop callouses on their hands as a result of everyday wear and tear. When a broken bone heals it also forms a callous at the fracture site that will be evident on x-rays for months and months after the bone has “healed.”

It may seem odd but one’s nerves can also form callouses at stress sites. Our nervous system is a flexible network that directs the movement of the body. Nerves can range in size from that of your index finger (the sciatic nerve of the leg) to tiny nerves smaller than the hairs on the back of one’s hand.

Morton’s neuroma is a common foot malady affecting runners and non-runners alike. The cause of Morton’s neuroma is mechanical stress, which is usually a combination of rubbing, compression or crush. The diagnosis of Morton’s neuroma is straight forward. There is a sensation of “something,” like stepping on a small stone, when one is in weight bearing. While diagnosis of Morton’s neuroma is straight forward prevention, treatment and resolution of the problem gets a little more complicated.

Together the feet contain 52 bones, representing 25% of all the bones in the body. Of note regarding Morton’s neuroma are the five long bones of the foot called the metatarsals. In between these long bones runs the plantar digital nerves that go all the way to the toes. It is the rubbing of the plantar digital nerves that creates the callous on the nerve that eventually presents as Morton’s neuroma.

While it is possible to develop Morton’s neuroma between toes one and two or toes two and three far and away the most common site it between metatarsals three and four. Figure 1 offers a schematic explanation. Note that between metatarsals three and four two branches of the plantar digital nerve combine. This makes for a slightly larger nerve (diameter wise) that when combined with the collapse of the metatarsal arch predisposes one to Morton’s neuroma. But, as with many healthcare issues this explanation is not a universally accepted explanation.

The controversy centers around the number of arches in the foot. To the lay public the foot has one arch. Some professions note that there are three. Having taught the foot for 20 years, I always taught that there are four. The justification for four will be apparent when we discuss treatment of Morton’s neuroma.

The medial longitudinal arch is on the inside of the foot. This is the arch a lay person would readily identify as their “arch” of the foot. There is also a lateral longitudinal arch that runs along the outside of the foot. The transverse arch runs across the top of the foot. A quick look at Figures 2,3,4 illustrates these three arches. The metatarsal arch or anterior transverse arch is made up of the five metatarsal bones. It is the collapse of this arch that creates the rubbing or crush conditions that lead to Morton’s neuroma.

The largest muscle in one’s foot is about the size of one’s thumb. Running at a moderate pace subjects the foot to ground contact forces 4-7x one’s body weight with each step that is repeated upwards of 1000x per mile. Add to this fact that training shoes can restrict the movement and even promote muscular atrophy of an already overwhelmed musculature of the foot. These circumstances hint why foot problems are so prevalent for runners.

Female runners often compound this problem with questionable shoe fashion choices that squeeze or unevenly load the metatarsals and restrict foot movement even further (i.e.- high heels and pointed toes). In truth, these are controllable precipitating factors. The challenge becomes what to do to correct the condition.

Possible Solutions

Initially there are three goals for resolving Morton’s neuroma; rest, decrease local inflammation and begin to strengthen the foot.

The #1 recommendation in the treatment of Morton’s neuroma is to get some rest. I realize that rest is a 4-letter word but attempts to soldier on with the hopes that Morton’s neuroma will “go away” on its own will just prolong the problem indefinitely, or at least until your altered gait pattern causes a knee, hip, low back or some other foot problem.

Use of a castor oil pack can help decrease the local inflammation caused by irritation to the nerve between the metatarsals. You will need 1) castor oil (check out BaarProducts.com), 2) some white cotton material and 3) some Saran Wrap. Wet the white cloth with the castor oil, wrap it around the metatarsals and then Saran wrap the cloth in place (the oil will stain bed linens). You might want to put a sock or Ace bandage over the Saran Wrap to hold that in place. Leave this castor oil pack on overnight. Repeat for three days, off for three days and repeat cycle.

A third goal is to strengthen the foot. I have no doubt someone is thinking, “I bet barefoot running would help this.” I disagree, especially in the acute stage. It will be too much stress on the foot and only prolong the problem. Don’t do it.

The ability to wiggle the toes is important. Most people have lost control of this function but practiced diligently motor control will return. This in turn will start to reawaken and tone the

small atrophied muscles of the foot. A second exercise that helps strengthen the foot is to lay a towel on the floor and scrunch-up the towel using the toes. In time one can add resistance by putting a book on the towel. See Figure 5 – Seated toe exercises for more suggestions.

A reduced training regime can begin when the pain is gone. I prefer recommending repeat 100m runs on a flat surface. In case the foot starts to hurt again one was only 100m from home. Cross training can also be used but be careful using a bicycle or Stairmaster as they both may exacerbate the foot pain.

There is an over-the-counter device called a “metatarsal pad” one can find at most pharmacies. In theory this metatarsal pad will “lift and separate” the metatarsal bones and help support the fourth arch, the metatarsal arch. While this product works okay with a non-runner the increased activity of a running (repetitive steps and sliding within the shoe) will compromise this pad. Even with adhesives they tend to roll up.

A better choice is to find an orthotic or arch support with a built-in metatarsal pad. Again, these orthotics are available at most pharmacies and also from various healthcare professionals (podiatrists, pedorthists, chiropractors). Prices can vary wildly. You may get relief with a generic support in the $10-20 range or require a more expensive personalized orthotic.

Hopefully one can see that a short-term and long-term goal is to strengthen the muscles of the foot. Once the pain has disappeared with weight bearing the 6 Foot Drills can be added (see “The 6 Foot Drills” 2:42 on YouTube). These drills will further condition the small muscles of the foot which will in turn offer a margin of error in the future. Once again, if one (or several) of the foot drills causes discomfort – stop – this is not a time to try to “gut it out.” Pain = no gain.

If one’s conservative attempts to resolve the problem in two weeks fails it is time to consult with a health care professional. Morton’s neuroma is a bread and butter issue for a podiatrist. More than likely they will recommend a cortisone shot to the troubled area. This should dramatically reduce the local inflammation and hopefully resolve the problem. But it warrants re-mention that the absence of pain does not mean the problem has been resolved. The strengthening suggestions need to become part of one’s “new training normal” or the problem will persist. Additionally, the long-term use of a metatarsal pad should preclude this problem happening again.

The final three recommendations to consider are regarding one’s shoes. Consider buying shoes that have a wider toe box. The toe box is the part of the shoe around the metatarsals and toes. The shoe should comfortably fit around the metatarsals and not be restrictive. Secondly, consider purchasing your shoes in the afternoon or the evening. It has been found that the human foot can expand as much as 4% over the course of the day. That is almost one-half inch for a 12” foot. Finally, consider folding your training shoes at the metatarsal area when you get a new pair. This will stretch the area of the shoe and slightly reduce the stress on the foot with each subsequent step.

Morton’s neuroma is a simple condition that usually resolves with some initial rest and conservative care. Its resolution may require training changes and training adaptations that require some personal discipline to implement. A strong foot is a healthy foot. Strengthening the foot therefore becomes a pre-eminent goal. If symptoms persist longer than two-weeks, it is a good idea to seek professional help.

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Russ Ebbets, DC is a USATF Level 3 Coach and lectures nationally on sport and health related topics. He serves as editor of Track Coach, the technical journal for USATF. He is author of the novel Supernova on the famed running program at Villanova University and the High Peaks STR8 Maps trail guide to the Adirondack 46 High Peaks. Time and Chance, the sequel to Supernova was published in May of 2018. Copies are available from PO Box 229, Union Springs, NY 13160. He can be contacted at spinedoctor229@hotmail.com

Russ Ebbets Archive

The Bijou Mile-Jog Down Memory Lane

Review of his book, Time and Chance

Peaking

Running Economy