Pes Cavus .... 38163s

PES CAVUS

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Pes cavus is a high arch of the foot that does not flatten with weight bearing. No specific radiographic definition of pes cavus exists. The deformity can be located in the forefoot, midfoot, hindfoot, or a combination of these sites.

PROBLEM 

The spectrum of associated deformities observed with pes cavus includes clawing of the toes, posterior hindfoot deformity (described as an increased calcaneal angle), contracture of the plantar fascia, and cock-up deformity of the great toe. This can cause increased weight bearing for the metatarsal heads and associated Metatarsalgia and calluses.

ETIOLOGY 

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The etiology of pes cavus can be identified approximately 80% of the time. The causes include malunion of calcaneal or talar fractures, burns, sequelae resulting from compartment syndrome, residual clubfoot, and neuromuscular disease. The remaining 20% of cases are idiopathic and nonprogressive. Neuromuscular diseases, such as muscular dystrophy, CharcotMarie-Tooth (CMT) disease, spinal dysraphism, polyneuritis, Intraspinal tumors, poliomyelitis, syringomyelia, Friedreich ataxia, cerebral palsy, and spinal cord tumors, can cause muscle imbalances that lead to elevated arches. A patient with a new-onset unilateral deformity but without a history of trauma must be evaluated for spinal tumors.

PATHOGENESIS 

Multiple theories have been proposed for the pathogenesis of pes cavus. Duchenne described intrinsic muscle imbalances causing an elevated arch. Other theories include the extrinsic muscle and a combination of the intrinsic and extrinsic muscles being causes of the imbalance

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(1992, Mann) described the pathogenesis of pes cavus in patients with CMT disease. An agonist and antagonist model for the muscles determines the deformity. In CMT, the anterior tibialis muscle and the peroneus muscle develop weaknesses. Antagonist muscles, posterior tibialis and peroneus longus, pull harder than the other muscles, causing deformity. Specifically, the peroneus longus pulls harder than the weak anterior tibialis, causing plantar flexion of the first ray and forefoot valgus. The posterior tibialis pulls harder than the weak peroneus brevis, causing forefoot adduction. Intrinsic muscle develops contractures while the long extensor to the toes, recruited to assist in ankle dorsiflexion, causes cock-up or claw toe deformity. With the forefoot valgus and the hindfoot varus, increased stress is placed on the lateral ankle ligaments and instability can occur.

CLINICAL PRESENTATION   

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Patients can present with lateral foot pain from increased weight bearing on the lateral foot. Metatarsalgia keratosis Ankle instability hindfoot varus The forefoot plantar flexion hindfoot varus

CLINICAL TEST 

The Coleman block test determines if the subtalar t is flexible. The test is performed by having a patient stand with a 1inch wood block under the heel and lateral foot. This allows the first ray to be plantar-flexed off the block. If the hindfoot corrects to a neutral position, the deformity is flexible. If the hindfoot does not correct, the deformity is rigid.

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Increased calcaneal angle

TREATMENT Medical therapy  The goal of treatment is to allow the patient to ambulate without symptoms. The underlying cause must be identified in order to determine if the disorder is progressive. The goal of surgery is to produce a plantigrade foot and pain relief. Repeat surgical procedures may be necessary, especially if the deformity is progressive. Preoperative patient education is essential for patient satisfaction.  Nonoperative treatment may provide patients with significant relief. Physical therapy to stretch tight muscles and strengthen weak muscles may provide early relief.  Orthotic with extra-depth shoes to offload bony prominences and prevent rubbing of the toes may improve symptoms. For varus deformities, a lateral wedge sole modification can improve function. Bracing for supple deformities or foot drop may allow patients to ambulate; however, in patients with sensation deficits, Plastazote linings in the brace are required and frequent inspection of the skin for ulceration is warranted.

SURGICAL THERAPY Correcting a cavovarus foot  Most of the corrections involve tendon transfers and capsular and facial releases  Correction of plantar flexion of the first ray by performing a dorsiflexion 1ST tarsometatarsal arthrodesis.  Reduction of hindfoot varus by performing a lateralizing calcaneal osteotomy. 

Arthrodesis 1st TMT t, lateral calcaneal osteotomy for hind foot varus

Lateral view showing both.

PLANTAR FASCIA RELEASE(MANN 1993) 

In pes cavus, the plantar fascia may become contracted. Plantar fascia release is usually combined with a tendon transfer, an osteotomy, or both. This is frequently the first step in improving the deformity

GREAT TOE JONES PROCEDURE 

A great toe Jones procedure is performed for a cock-up deformity of the great toe with associated weakness of the anterior tibialis muscle. In this case, the EHL has been recruited to assist in ankle dorsiflexion, which causes hyperextension at the MTP t and hyperflexion at the interphalangeal (IP) t. This procedure transfers the EHL to the neck of the first metatarsal, with arthrodesis of the IP t to improve the dorsiflexion of the ankle and remove the deforming force at the MTP t

EXTENSOR SHIFT PROCEDURE 

The extensor shift procedure involves transferring the EHL and the extensor digitorum longus (EDL) to the first, third, and fifth metatarsals. The technique includes completion of the Jones procedure, with incisions in the second and fourth web space. The tendons are harvested. The second and third tendons are transferred through a drill hole on the third metatarsal, and the fourth and fifth tendons are transferred to the fifth metatarsal.

GIRDLE STONE TAYLOR TRANSFER 

The Girdle stone-Taylor transfer procedure is used for flexible claw toe deformities. The deforming force of the flexor digitorum longus tendon is transferred to the extensors to correct the deformity.

Base of the first metatarsal osteotomy 

In patients with a fixed plantar-flexed first ray, a base of the metatarsal closing wedge osteotomy corrects the deformity, which is especially observed in CMT disease. This procedure is usually combined with a plantar fascia release in a mild deformity or a Jones procedure

Midfoot osteotomy 

Tarsal osteotomy has been described for deformities through the Midfoot; however, these osteotomies require cutting through multiple ts. They are quite technically complex and are rarely performed

Peroneus longus to peroneus brevis tenodesis 

In patients with CMT disease who have a weak peroneus brevis (PB) and a preserved peroneus longus (PL), a tenodesis can be performed to help stabilize the ankle. This is frequently combined with a calcaneal osteotomy

Calcaneal osteotomy 

Patients with hindfoot involvement usually require a calcaneal osteotomy to correct the deformity. The osteotomy can include a closing wedge, a vertical displacement, or a combination (triplaner osteotomy). This procedure is usually combined with a plantar fascia release and, frequently, a tendon transfer.

Beak triple arthrodesis 

The Siffert beak triple arthrodesis corrects pes cavus deformities through wedge resection and a triple arthrodesis. This procedure is used for treatment of rigid fixed deformities in adults. The technique involves mortising the navicular into the head of the talus and depressing the navicular, cuboids, and cuneiforms to improve forefoot cavus deformities. This procedure is complex and technically demanding

OUTCOMES AND PROGNOSIS The results of surgical intervention are difficult to compare because of the multiple possible combinations of procedures necessary for successful treatment  Also, patients have varying degrees of deformity, disease progression, and underlying etiology, making comparison virtually impossible; however, some positive findings have been reported. 

RESEARCHES 

Wetmore and Drennan's report that 24% of patients with CMT disease who underwent a triple arthrodesis had satisfactory results at an average of 21 years of follow-up. They recommended the triple arthrodesis as a salvage procedure.

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Mann and Hsu reported on 12 feet in patients with CMT disease that underwent triple arthrodesis, with a follow-up that averaged 7.5 years. Five feet were plantigrade, asymptomatic, and united. Three feet were plantigrade and asymptomatic but had nonunion. Four feet were nonplantigrade and symptomatic. The authors stated that positioning is the key to satisfactory results.

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Roper and Tibrewal reported the results of soft-tissue procedures combined with osteotomies. Ten cases of CMT disease were reviewed 14 years after surgery. Two patients required repeat surgery secondary to recurrent deformity. At last follow-up, all patients had plantigrade feet, without requiring a triple arthrodesis.

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Gould discussed 18 feet in 10 patients with a 3- to 6-year follow-up. All had satisfactory results with soft-tissue procedures combined with osteotomies, and all patients had plantigrade feet at last follow-up

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