High Arch (Pes Cavus)
Some people think ”Oh, I have a high arch, that must be a good thing.” Actually the opposite is true. Both high arches and low arches can cause problems. Some of the common problems associated with a high arch are lateral foot overload, foot intrinsic weakness, and increased risk of ankle sprains.
For Medical Professionals:
As to the prevalence of the subtle cavus foot, it is around 25%. That doesn’t mean that all 25% are symptomatic. Also, many of those with subtle cavus cannot be recognized unless measurements are done on weight-bearing xrays of the feet. I look at many metrics, but always pay close attention to Meary’s line, also called the “talus-first metatarsal line.” It should be straight on both the AP and Lateral weight-bearing views.
Even though it is subtle, the constellation of symptoms and history is fairly consistent. I usually see any and often all of the following:
Mulitple Ankle Sprains:
History of multiple inversion sprains/twisted ankles as a teenager or continuously throughout life. If the patient is still having trouble with sprains or symptoms are worse with passive (forced) inversion and they likely have recurrent ankle instability, I recommend the Bauerfind Malleoloc brace to be used any time the patient is doing higher-risk activities or as needed to manage symptoms. The Malleoloc is great for coronal plane control, especially to prevent inversion, while still allowing plantarflexion/dorsiflexion at the ankle. Lace-up braces seem to be equally ineffective at stabilization in all planes. Same with the Aircast “stirrup” brace.
Peroneal Tendon Injuries:
Lateral ankle pain from tension-side injury to lateral ankle ligaments and peroneal tendons. Sometimes laxity and attenuation, sometimes even frank tears. Peroneus brevis usually injured, peroneus longus spared. Remember peroneus longus crosses under the foot to attach to the underside of the base of the 1st metatarsal and plantarflex it: which is perhaps the main problem with subtle cavus feet (the forefoot-driven hindfoot varus type).
Lateral foot pain:
From lateral overload, usually at or near the base of the 5th metatarsal. The weight-bearing axis no longer passes through the center of the foot “tripod.” Instead, it is centered over the lateral bones, which are not suited for such high loads. This may also be from inability of the subtalar joint to evert at all and thus allow physiologic flattening of the arch which brings the weight over the medial forefoot. (Pronation and supination are imprecise terms, so I will avoid them.)
Medial ankle joint pain:
As the ankle joint has a varus force or even a varus subluxation, the medial talar dome and/or the medial tibial plafond articular surfaces are overstressed, while the lateral aspects of both are understressed. This can lead to, or exacerbate, a talar dome osteochondral lesion.
Distal 1st metatarsal pain (ball of the foot, medially):
From the 1st met trying to drill through the ground to get out of the way and let the foot come down to where it should. You’ll often see excessive calluses of the skin there. Diffuse forefoot pain from overload if the condition is paired with a tight heel cord (95% of the time it is the gastrocnemius ONLY). This can only be tested with the knee straight and the person completely relaxed. Tight gastrocs are an under-recognized cause of a TON of foot and ankle problems. Also, stretching the gastroc is not as simple as doing the “runner’s stretch” with your hands on the wall and the foot out behind you. That allows the foot and ankle to “cheat.” Problems in the extremity more proximally and even all the way up the body.
The subtalar joint is locked all the way over into max inversion and stuck there because the joint capsule has contracted into the new shortened position. That leaves the person with usually zero eversion and therefore no ability to compensate for uneven ground. It also does not allow the foot/ankle to progress through the normal intricate movements of locomotion. The arch is dynamic! It goes up and down with every step/stride. The cavus foot is stuck in one position and can’t do all the normal movements and also can’t compensate for different surfaces. This can cause excessive impact forces. Just an increased impact loading RATE is enough to lead to chronic injury such as stress fractures and tendinitis. These eventually lead to acute injury when the body’s repair mechanisms can’t keep up with the re-injury rate.
Foot Scientific Type 3 Shoe Insert:
There is NO other device that you can put in a shoe that does what the Type 3 cavus-specific insert does. There are other brands that try to address the problem, but they are bad for various reasons that I won’t go into here. The Type 3 allows the distal 1st met and great toe to drop down in to a lower position and the entire lateral foot from front to back is posted (raised up). This allows the foot to do what it has been trying to do all along and can, hopefully, allow the subtalar joint to unlock and start to stretch out the joint capsule. Then, the exercises and drills about can begin to take effect and hopefully start building a more normal foot that is more flexible, strong, and mobile. I always tell patients to put the Type 3 into a shoe that is as flat as possible. One that has the least amount of “technology” as possible. That lets the Type 3 be the only thing that’s doing something. See my recommended shoe list. They have what I like to call a “human shape” and most of them have soft, forgiving uppers that are kinder to the dorsal prominence on the top of the subtle cavus foot (at the apex of the plantar-flexed 1st TMT joint). Lastly, don’t let anyone ever put an arch “support” in your shoe! That will make the problem worse!
Click here to see my physical therapy protocol for nonoperative treatment of High Arches (Cavus foot)
Click here to learn more about high arches from the American Orthopedic Foot and Ankle Society