Consequences to a high-arched foot

Conway McLEAN, DPM

Know anyone who has sprained their ankle? Do you know anyone who hasn’t? Isn’t that a better question? Because of its weight-bearing function and the construction of this joint, the ankle is the most commonly injured joint among athletes, and a frequent cause of pain and problems in the general population. Some people have problems with recurrent ankle sprains, and feel like they can turn their ankle on a tiny crack in the sidewalk. Why does this happen so easily and so frequently to some? The explanation I hear so often is they have “weak ankles”, when, in actuality, they often have a deformed foot, the dreaded cavus foot!

Everyone is aware of the flattened foot type, which is a common (and often discussed) source for a variety of painful problems. But what about the opposite condition, in which the foot has too high an arch?

Don’t forget the ancient bit of wisdom “Too much of anything is a bad thing”! Indeed, in nature, this is more of a rule than a clichée. Nature is all about balance, in all things, and this holds true for the functioning of the general architecture of the foot.

You may be wondering at this point about the connection between ankle sprains and the high-arched cavus foot. Picture in your mind, if you will, the stability of a flattened foot type, in which much of the bottom of the foot is in contact with the ground.

This provides a much more stable support for the rest of the body. In contrast, a cavus foot is constructed more like a tripod, with the foot perched up in the air, resting on three points of contact, the heel and two metatarsal bones. Think about how much more stable a car is, with its four wheels, compared to a three-wheeled vehicle.

For years, orthopedic literature concerned itself primarily with the association between a high arched foot and certain neurologic diseases. Indeed, there is a strong correlation with a severely raised arch type and conditions which alter the innervation of the muscles to the legs.

A variety of diseases cause muscle control problems, such as Charcot-Marie-Tooth disease and other muscular dystrophies. An imbalance between some of the muscle groups running from the leg down to the foot seems to be the primary factor in the presence of a severe cavus foot.

But arch height varies greatly from person to person in those without a neuromuscular disease, and recent research has examined the effect of the cavus foot type on body mechanics. This foot type often possesses a heel bone which curves inward more than normal.

The effect is that the force of body weight, traveling down the ankle, will land to the outside of the heel’s contact point and tend to cause the foot to turn inward. Voila! The ankle twists, leading to your typical sprain. Of course, this may be very mild, producing no significant pain, but that feeling of instability is so common.

Surprisingly, ankle sprains are not the most common symptom of this foot type. Even a mild form of the cavus foot will alter that delicate muscle balance referred to earlier. As faithful readers know, toes stay in proper position because of a delicate balance of structures. Various muscles, working in opposition to others, are critical to keep the toes straight. With this foot type, that balance is thrown off, resulting in greater power to the muscles on the top of the foot. This leads, over time, to claw toes, where the toes are all rigidly bent down, and pulled up at the ball of the foot. Clawing of the toes can have a variety of consequences. The amount of pressure placed on the ball of the feet is increased with the higher arched foot, but when the toes are raised up, the pressure is even greater. Many people experience this kind of pain whenever they walk or stand more, a result of the architecture of the foot, and the positioning of the toes on top of the metatarsals.

Additional effects of this foot type include the development of that scourge of the modern age, plantar fasciitis. This is the condition generally responsible for heel pain, where the arch ligament running along the bottom of the arch, gets stretched too much and becomes inflamed. The cavus foot is unable to absorb the impact of walking (or running) appropriately, and excessive shock from each step is placed on this structure. Pain may be experienced with every step when someone with a cavus foot develops plantar fasciitis. Standing for longer periods can also be an agonizing experience.

Another manifestation of this foot type is excessive callusing of the ball of the foot, as well as the heel. Callusing is a predictable consequence of excessive pressure to the skin. That is the situation with the high arched foot. Sometimes these people have lived all their lives with thick, painful calluses, and so regard it as normal.

Know anyone with knee pain? Again, this is more of a rhetorical question since it is nearly impossible not to. Naturally, there are many reasons for the occurrence of knee pain, but sometimes it is the lack of shock absorption because of a high arched foot. The foot and knee are the two main shock absorbers in the body. Because the cavus foot cannot accommodate the impact forces of ambulation well, there is greater stress to the knee, and thus it is more likely to develop osteoarthritic changes.

If you or a family member recognize these signs and symptoms of a cavus foot deformity, you may be wondering at this point if there is some treatment. Conservative measures are generally very successful for this condition, with specific options depending on what problems one is having. Preventative care for some of the potential problems includes, most importantly, the use of prescription arch supports, aka foot orthoses (orthotics), to control some of the aberrant mechanical changes. Foot orthotics can also be prescribed to reduce the pressure to the ball of the foot and heel. Properly prescribed supports will also minimize the likelihood for further sprains, and improve ankle stability, by providing a more stable foundation for the musculoskeletal system.

When the deformity is more severe, or surgery is being proposed due to some associated pathology (for example, damage to the ankle ligaments because of another sprain), various procedures are utilized to correct the deformity. The techniques chosen will depend on the sufferer’s foot architecture. One of the more commonly performed involves making a cut in the heel bone to realign it. Additionally, it is often necessary to raise the first metatarsal bone, since it is often too “low” in this foot type. Other techniques exist, and a detailed evaluation is required to determine the appropriate ones (although only after conservative care has been exhausted).

In closing, let me say that it is critical that the presence of a neuro-muscular disease be determined when someone has a cavus foot type. But it is more common that the higher arch is a normal variant, and no neurologic condition exists. Many successful conservative options for care are available, from a great variety of ankle braces to special callus creams. Shoes are also important, although prescription, in-shoe supports, the aforementioned foot orthotics, is probably the most critical, and effective, method of conservatively treating the cavus foot.

There are normal feet out there, but for many people, their foot architecture and lower extremity mechanics benefit from more customized support than can be found in a shoe. Don’t ignore your feet, because you need them. They are homo sapiens’ oldest form of locomotion, even if most other members of the animal kingdom do have “four on the floor”!

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.