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Cavus Foot

Pes cavus, cavovarus, or high-arch foot are all descriptive terms used to describe a foot in which the arch is higher than typical population norms. It is the opposite of pes planus, or flatfoot, in which the foot has little or no arch. Sometimes a cavus foot, just like a flatfoot, can be problematic. However, the problems seen with cavus feet are generally different, and in some ways, opposite of the problems seen with flat feet.

Severely cavus feet may not fit into shoes very well because of their shape. They can seemingly toe-in when walking. They may appear to have a humpback deformity with 'bossing' on top of the foot that can become painful from shoe pressure where the laces tie across the foot.

A cavus foot is less flexible than a flatfoot. For this reason, during walking, cavus feet do not absorb shock as well. Due to this stiffness and rigidity, a cavus foot is more prone to arthritic changes in the midfoot and hindfoot. These arthritic changes may cause the bone to remodel and grow spurs (osteophytes), which can exacerbate the painful pressure and bossing on top of the foot. The arthritic changes may also cause achiness in the arch and the midfoot after a long day of standing or walking. This lack of flexibility and shock absorption may also predispose to other foot conditions such as plantar fasciitis related heel pain (see section on plantar fasciitis).

Patients with cavus feet can also present with symptoms of lateral ankle instability (see section on ankle sprains). Ankle instability is a diagnosis in which patients have recurrent ankle sprains, or the feeling that their ankle is unstable or will give way. The causes of ankle instability are variable but may be influenced by foot shape. Patients with cavus feet tend to walk on the outer border of the sole (lateral column) or the side of the foot. Based on laws of physics, walking on the outside of the foot puts tension on the lateral soft tissue restraints and renders these individuals more prone to 'rolling' the ankle, and experience an ankle sprain. Severe ankle sprains can lead to permanent damage of the lateral ligaments and tendons, which leads to even more sprains or further instability. This can become a cycle leading to increased sprain frequency and increased ankle damage such as anterior talofibular ligament (ATFL) tears, peroneal tendon tears, and cartilage damage (osteochondral defects).

Even in patients with cavus feet who don’t experience severe sprains or instability, the peroneal tendons (see section on peroneal tendons), which serve to stabilize the ankle, may become overworked or injured. As the patient walks on the outer sole of the foot, the peroneal tendons work to stabilize the foot and keep it from rolling in and preventing sprains. This can lead to soreness, tendonitis, or painful spasm of the tendons and sometimes peroneal tendon tears. Often times, in order to successfully repair peroneal tendon damage, the cavus shape of the foot must be addressed simultaneously.

After Surgery

The recovery from surgical correction of a cavus foot is variable, but generally, a non-weight bearing period of 6 weeks is required. This usually involves a splint immediately after surgery and stitch removal at 2-3 weeks. Sometimes a cast may be subsequently used for a few weeks. Bone healing at the fusion or osteotomy site is the rate-limiting step.  Around 6 weeks weight bearing in a boot is allowed and physical therapy is commenced. Transition into a standard shoe generally occurs around 12 weeks postoperatively.
Before Surgery
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After Surgery
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Surgical Intervention

Surgical correction of a cavus foot may require multiple procedures to decrease or flatten the high arch to a more normal level. The descriptive term cavus foot includes a number of multiplanar deformities ranging from the hindfoot (heel) to the forefoot (toes). Sometimes this is referred to as hindfoot varus, midfoot adduction, and forefoot valgus position. To effectively flatten the arch, it may require a combination of multiple osteotomies (cutting and shifting the bone) of the heel, midfoot, and forefoot. Sometimes tendons may be released or transferred as part of the correction to further balance out the foot and help maintain the corrected position. Cavus foot balancing procedures may also be necessary with surgeries primarily  addressing other pathologic conditions such as ankle instability, peroneal tendon tears, midfoot arthritis, or ankle arthritis. It is common in patients with high arches and ankle arthritis to necessitate correction of their cavus foot either prior to, or simultaneous to, their ankle replacement procedure.
Common procedures include a 'gastrocnemius recession' which may be necessary to release tight contracted heel cords. The heel is generally shifted to the outside of the sole and away from the midline with a 'lateral calcaneal slide osteotomy' or a 'subtalar fusion'. 'Posterior tibial tendon release or transfer' may remove the inversion deforming force and the tendon may be transferred elsewhere to help pull the foot in the opposite direction. In addition to releasing the posterior tibial tendon, 'midfoot capsular and ligament releases' of contracted tissue may be necessary to move the foot to a better position. 'Peroneal tendon repair or longus to brevis transfer' may be used to further balance the deforming forces. Lastly, a '1st metatarsal dorsiflexion osteotomy' or a 'dorsal closing wedge midfoot fusion' can be used to collapse the high arch humpback deformity. Often times, the most effective use of these procedures may require intraoperative decision making once the patient is sedated and relaxed. There are a multitude of other procedures that may be used solely or in combination to help address a cavus foot. 
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