Pes cavus, commonly referred to as a high-arched foot, is a structural deformity where the longitudinal arch of the foot is significantly elevated, even when bearing weight. This condition occurs in an estimated 8 to 15 percent of people. Pes cavus alters the way the foot contacts the ground and distributes pressure, often leading to pain and instability over time.
Defining the Pes Cavus Deformity
The pes cavus deformity is characterized by an abnormally high medial arch that does not flatten when the person stands. This configuration limits the contact area between the foot and the ground, concentrating weight onto the heel and the ball of the foot. Key components include a hindfoot varus, where the heel turns inward, and a plantarflexed first ray, meaning the metatarsal bone leading to the big toe points downward excessively. This plantarflexion of the first ray often drives the rest of the foot to tilt and the arch to elevate. The deformity is classified by its flexibility, ranging from a flexible form that corrects when pressure is removed to a rigid, fixed structural deformity.
Underlying Causes and Associated Conditions
The etiology of pes cavus is often linked to the nervous system, as approximately 70 percent of severe cases can be traced back to a neuromuscular disorder. The most frequent neurological cause is Charcot-Marie-Tooth (CMT) disease, a hereditary sensory and motor neuropathy that progressively weakens muscles. Other conditions affecting the spinal cord, such as myelodysplasia, polio residuals, or Friedreich’s ataxia, can also lead to the development of a high arch.
The deformity arises from an imbalance between the opposing muscle groups in the leg and foot. In conditions like CMT, muscles that lift the foot and stabilize the arch, such as the tibialis anterior and peroneus brevis, become weak. This weakness leaves stronger muscles, like the peroneus longus and posterior tibialis, unopposed, allowing them to pull the foot into the characteristic deformed position.
While most pes cavus cases are neurological, some are considered idiopathic (cause unknown) or result from trauma. Idiopathic cases are often milder and non-progressive. Traumatic causes, such as improperly healed fractures of the heel bone or ankle, can disrupt the foot’s alignment, leading to a fixed high-arched foot structure.
Recognizing the Symptoms and Biomechanical Effects
Individuals with a high-arched foot often experience pain localized to the ball of the foot (metatarsalgia) and the heel due to abnormal weight distribution. The limited ground contact area leads to high plantar pressures in these regions, commonly resulting in painful calluses and corns. The combination of hindfoot varus and the elevated arch forces the foot into a supinated position, meaning weight is carried disproportionately on the outer edge.
This faulty alignment compromises the foot’s ability to absorb shock during walking and running. The rigid structure of a cavus foot prevents the natural pronation mechanism required for shock absorption. Poor shock absorption transmits greater forces up the kinetic chain, potentially contributing to discomfort in the knees, hips, and lower back.
The persistent supination and inward-turned heel can strain the ligaments on the outside of the ankle, often leading to recurrent ankle sprains and chronic lateral ankle instability. Structural changes also manifest as difficulty fitting standard footwear due to the high instep and clawing of the toes. Claw toes are a frequent symptom where the toes are hyperextended at the joint closest to the foot. This toe deformity exacerbates pressure points and can lead to ulcers, especially in patients with underlying sensory neuropathy.
Comprehensive Management Strategies
The primary goal of managing pes cavus is to relieve pain, improve function, and establish a stable foot that can rest flat on the ground. Management typically begins with conservative, non-operative measures, which are often effective for flexible or mild deformities. Custom-molded foot orthoses are fundamental, designed to redistribute plantar pressures and provide support under the arch.
These orthotics often incorporate a forefoot valgus post, which helps counteract the downward tilt of the forefoot and reduce the varus of the heel. Physical therapy focuses on stretching tight muscles and soft tissues, particularly the plantar fascia and calf muscles. Bracing, such as an ankle-foot orthosis, may also be prescribed to provide external stability for individuals experiencing significant ankle instability or muscle weakness.
When conservative treatment fails or for cases involving severe, rigid, or progressive deformity, surgical intervention becomes necessary. Surgical procedures are individualized and can include a combination of soft-tissue releases, tendon transfers, and bony corrections. Soft-tissue procedures, such as plantar fascia release or lengthening of contracted tendons, address flexibility issues.
Bony procedures, known as osteotomies, involve cutting and reshaping bones in the foot and ankle to correct the underlying structural malalignment. For the most severe, fixed deformities, a joint fusion procedure (arthrodesis) may be required to permanently stabilize the foot into a functional position.