OverviewPes cavus is an umbrella term describing a spectrum of foot shapes with a high arch. Pure Pes cavus occurs when the metatarsal bones are plantarflexed relative to the hindfoot described as ?forefoot plantaris? which increases the height and curvature of the medial longitudinal arch. When the patient weight-bears, the hindfoot is pushed into dorsiflexion by the plantarflexed forefoot.
CausesCavus foot commonly occurs as a result of an underlying medical or neurological condition, such as polio, muscular dystrophy or cerebral palsy. Cavus foot may also occur as a result of congenital defects. They may be inherited from a parent, or they may result from an orthopedic condition or a disease of the nerves or muscles.
SymptomsPatients often complain of pain, instability, difficulty walking or running and also problems with footwear. There is often a range of other foot deformities also present eg, claw toes, increased calcaneal angle, 'cocked-up' big toe.
DiagnosisThe key in examining the foot is to determine to what extent deformities are fixed or flexible. This guides orthotic and surgical treatment. Gait is inspected; in HSMN the typical gait is high-stepping because of foot-drop, with the toe striking the ground before or with the heel. Foot shape is best assessed with the patient standing. The soles are inspected for calluses and the shoes for differential wear (indicating sites of excessive pressure). Tender areas, such as the metatarsal heads or base of the fifth metatarsal, are palpated. Passive movements should be assessed, looking for joint contractures. Testing active movements detects muscle weakness. The Coleman block test is one way to determine whether the hindfoot is flexible. With the patient standing, the heel and fifth ray are placed on a wooden block, permitting the forefoot to pronate. If the hindfoot also pronates, it is flexible; if not, it is in fixed varus.
Non Surgical TreatmentNon-surgical treatment of cavus foot may include one or more of the following options. Orthotic devices. Custom orthotic devices that fit into the shoe can be beneficial because they provide stability and cushioning to the foot. Shoe modifications. High-topped shoes support the ankle, and shoes with heels a little wider on the bottom add stability. Bracing. The surgeon may recommend a brace to help keep the foot and ankle stable. Bracing is also useful in managing foot drop.
Surgical TreatmentSoft-tissue surgery. Cavus foot is caused in part by an over-pull of one of the lateral ankle muscles. A release of this tendon can be performed on the outside of the ankle. Additionally, a transfer of this tendon can be performed to help in correcting deformity of the ankle joint. Often patients will have a tightness of their gastrocnemius muscle, one of the main muscles in the calf. This can increase the deformity or prevent a correction from working. It is addressed with a lengthening of a part of the calf muscle or
How do I stretch my Achilles tendon? tendon. This is often performed through one or more small cuts in the back of the leg/ankle. Finally, the plantar fascia may be tight. The plantar fascia is a cord-like structure that runs from the heel to the front part of the foot. Partial or complete plantar fascia release may be done. Tendon transfers. Too much pull of certain muscles and tendons is often the cause of the deformity related with a cavus foot. Moving one of these muscles or tendons may help the foot work better. In addition, patients with a cavus foot may have weakness in moving the foot up, which is sometimes called a foot drop. In these cases, a tendon from the back of the ankle may be moved to the top of the foot to help improve strength. Bony surgery. Correcting the deformity of the foot may not be possible with soft tissue procedures alone. In these instances, one or more bone cuts (osteotomies) may be needed. Instead of a bone cut, a fusion (arthrodesis) procedure may be used. A fusion removes the joint between two bones so they grow together over time. During a fusion the bones may be held in place with plates or screws. Dorsiflexion osteotomy of the first metatarsal. This procedure flattens out the arch. Calcaneal osteotomy. This procedure is performed to bring the heel bone back under the leg. This is needed if correction of the deformity in the front of the foot does not also correct the back of the foot or ankle. A calcaneal osteotomy can be performed several ways and is often held in place with one or more screws. Fusion. Sometimes patients have a deformity that has caused damage to the joints. In these cases, soft tissue procedures or bone cuts may not be enough, and it may be necessary to eliminate the joint. Toe surgery. Clawed toes are a common problem with cavus foot deformity. This can be treated with tendon surgery, fusion or removal of part of the toe bones. Following surgery the toes are often temporarily held in place with pins.