How To Treat The High Arched Cavus Foot

Author(s): 
Bob Baravarian, DPM

Cavus foot pain can be a difficult and challenging problem. It is far less common to see a high arch patient with foot pain than a low arch patient with foot pain. As a result, high arch feet are less commonly treated or may be less understood than the common flatfoot.

   Furthermore, Charcot Marie Tooth muscular dystrophy has been associated with high arch feet and may lead to muscle imbalance issues that make the high arch foot more difficult to diagnose and treat. Accordingly, let us take a closer look at the workup and treatment options of the high arch foot.

   Patients who present with symptomatic high arch feet often note pain on the lateral column of the foot, instability of the lateral ankle and pain under the ball of the foot, especially under the first metatarsal bone. Problems such as plantar fasciitis can also occur with high arch flexible feet as the arch stretches during the gait cycle, causing stretching of the fascia. Patients usually feel like they are falling over on the outside of the ankle and may even find swelling and pain in the lateral foot and ankle. Severe cases of cavus may even lead to lateral column stress fractures.

What To Consider In Making A Diagnosis

The diagnosis of symptoms occurs through conducting a history and physical in combination with diagnostic testing. A history of familial high arches and any muscular dystrophy type symptoms in the family are important to consider. The type of pain and what causes the pain to begin are also important to consider. For example, patients who have pain with walking in comparison to only having pain when running may need more aggressive treatment than patients who only have pain with high impact exercises.

   Examination of the muscle groups and muscle strength is important. Furthermore, pain along the peroneal tendons may be a sign of a peroneal tendon tear. This may result in a cavus foot much like a posterior tibial tendon dysfunction may result in flatfoot. Instability of the lateral ankle may also lead to a cavus foot position as the talus deviates into a varus position due to the laxity of the lateral ankle ligaments.

   Finally, a plantarflexed first metatarsal or a varus heel may lead to a fixed cavus position due to a structural deformity. It is rare to see a pan-forefoot cavus deformity of all the metatarsals but one must also consider this possibility. In general, the first ray is plantarflexed far more often than all the metatarsals.

   Diagnostic testing often includes magnetic resonance imaging (MRI) if one suspects a peroneal tendon problem or ankle instability. Perform electromyography and nerve conduction velocity testing if you suspect Charcot Marie Tooth. If a high suspicion of muscular dystrophy is present, perform a sural nerve biopsy.

A Guide To Treatment Options For The Cavus High Arch Foot

Conservative care is highly successful in the cavus high arch foot. An orthotic with a high lateral heel flange, a valgus post and a sub-first metatarsal cutout can balance the foot. Often, the first ray is plantarflexed and a cutout of the first metatarsal head is essential for forefoot balancing. In severe ankle instability cases, an over the counter ankle-foot orthotic or a custom ankle-foot orthotic can be beneficial in balancing the foot and ankle. Consideration of a first ray cutout should also be part of the bracing process.

   In severe cases of cavus, surgical intervention is often necessary. The main consideration for surgical planning is the cause of the cavus deformity. Consider whether it is a structural deformity or one caused by an underlying traumatic event such as a peroneal tendon tear or ankle instability. Furthermore, in either a structural or traumatic case, it is important to consider if the cavus is from a plantarflexed first ray only, a calcaneal varus only or a combination of the two deformities together. After considering all the information, one can plan for surgery.

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