Pes Cavus 

Updated: Nov 14, 2018
Author: Norman S Turner, MD; Chief Editor: Thomas C Dowd, MD 

Overview

Background

Pes cavus is a descriptive term for a foot morphology characterized by high arch of the foot that does not flatten with weightbearing. No specific radiographic definition of pes cavus exists.[1] The deformity can be located in the forefoot, the midfoot, the hindfoot, or a combination of these sites.[2]  Whereas pes cavus is a common finding, occurring in approximately 10% of the general population,[3] it can also be a sign of an underlying neurologic disorder.[4]

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 cockup deformity of the great toe. This can cause increased weightbearing for the metatarsal heads and associated metatarsalgia and calluses.

Etiology

The etiology of pes cavus can be determined approximately 80% of the time. Possible causes include the following:

  • Malunion of calcaneal or talar fractures
  • Burns
  • Sequelae resulting from compartment syndrome
  • Residual clubfoot
  • Neuromuscular disease

The remaining 20% of cases are idiopathic and nonprogressive. Identifying the etiology is essential to determine if the deformity is progressive, which assists in operative planning.

Neuromuscular diseases, such as muscular dystrophy, Charcot-Marie-Tooth (CMT) disease,[5, 6, 7, 8, 9, 10]  spinal dysraphism, polyneuritis, intraspinal tumors, poliomyelitis, syringomyelia, Friedreich ataxia, cerebral palsy, and spinal cord tumors, can cause muscle imbalances that lead to elevated arches.[11] A patient with a new-onset unilateral deformity but without a history of trauma must be evaluated for spinal tumors.

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.

Mann described the pathogenesis of pes cavus in patients with CMT disease.[12] An understanding of the muscles involved and the sequence of the involvement helps in understanding the deformity. An agonist-antagonist model for the muscles determines the deformity. In CMT disease, the anterior tibialis and the peroneus brevis develop weaknesses. Antagonist muscles, the posterior tibialis and the peroneus longus, pull harder than the other muscles, causing deformity.

Specifically, the peroneus longus pulls harder than the weak anterior tibialis, causing plantarflexion of the first ray and forefoot valgus.[13] 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 cockup 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.

In patients with polio, the deformity is in the hindfoot and is caused by weakness of the gastrocnemius-soleus complex. This leads to a marked increase in the calcaneal pitch angle with normal forefoot alignment.

Prognosis

The results of surgical intervention are difficult to compare because of the multiple possible combinations of procedures necessary for successful treatment. Moreover, patients have varying degrees of deformity, disease progression, and underlying etiology, making comparison virtually impossible.

Nevertheless, some positive findings have been reported, such as 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.[14]  They recommended the triple arthrodesis as a salvage procedure.

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.[12]  Five feet were plantigrade, asymptomatic, and united. Three feet were plantigrade and asymptomatic but had nonunions. Four feet were nonplantigrade and symptomatic. The authors stated that positioning is the key to satisfactory results.

Roper and Tibrewal reported the results of soft-tissue procedures combined with osteotomies.[15]  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.

Gould discussed 18 feet in 10 patients with a 3- to 6-year follow-up.[16]  All had satisfactory results with soft-tissue procedures combined with osteotomies, and all patients had plantigrade feet at last follow-up.

Sugathan et al treated lesser-toe clawing in 11 feet (eight patients) with flexible pes cavus using a modified Jones procedure.[17]  At final clinical review, all 11 feet were improved, with minor complications in six. The mean Bristol Foot Score was 27, and the mean modified American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Score was 76, which indicated excellent results. Half of the patients had mild persistent foot pain, but all were satisfied with the outcome.

Naudi et al reported radiologic and clinical results with anterior tarsectomy in 39 cases (33 patients) of pes cavus.[18]  Pain decreased considerably in 75% of cases, and 68% of patients recovered normal activity. The foot was aligned correctly in 67% of cases, but at last follow-up, pes cavus remained undercorrected in 80%. In 74% of feet, adjacent joints showed progressive osteoarthritic degeneration. Subjectively, 70% of patients were very satisfied or satisfied with minor reservations, and objective outcome was excellent or good in 66% of feet.

According to Naudi et al, the overall results of this study showed that outcome in terms of function, motion, complications and satisfaction was good, but pain relief results were poor.[18]  They added that anterior tarsectomy is able to correct initial pes cavus deformity and compensate anomalies of the hindfoot, but its correction capacity is limited, and its efficacy in case of clawfoot is poor.

Limitations to the literature exist. Most of the reported results include reviews of adolescents rather than adults. Multiple variables are included with a small population of patients; however, the current trends are toward soft-tissue procedures combined with osteotomies. Arthrodesis is reserved for salvage procedures.

 

Presentation

History

The presentation for patients with pes cavus is highly variable, depending largely on the extent of the deformity. Patients can present with lateral foot pain from increased weightbearing on the lateral foot.[19]  Metatarsalgia is a frequent symptom, as is symptomatic intractable plantar keratosis. Ankle instability can be a presenting symptom, especially in patients with hindfoot varus and weak peroneus brevis. Weakness and fatigue can be observed in patients with neuromuscular disease. Symptom severity is as variable as the symptoms themselves.

Evaluation of a patient who presents with pes cavus begins with a thorough history and complete examination to determine the etiology. Patients with a unilateral deformity frequently have a history of major trauma. Neuromuscular disorders can be identified on the basis of the family history. A new-onset unilateral deformity is highly suggestive of a spinal cord tumor and necessitates an appropriate workup.

Physical Examination

Examination begins with observation of the gait. Hindfoot positioning is evaluated through gait analysis looking for varus. During swing phase, analysis of foot positioning is carried out, looking for anterior tibialis weakness and foot drop. Cockup toes can be observed with recruitment of the extensor hallucis longus (EHL). The shoe should also be inspected for increased lateral wear.

The range of motion of the ankle, subtalar, midfoot, and forefoot is examined. The deformity is determined to be flexible or rigid. The forefoot is observed for plantarflexion, and the hindfoot is observed for varus. Documenting the strength of the individual muscles is essential for determining surgical options. Agonist and antagonist muscle weakness must be carefully examined, especially in Charcot-Marie-Tooth (CMT) disease.

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

A neurologic examination is required, specifically including detailed muscle strength testing. Sensory examination reveals deficits that can be observed in CMT disease.

 

Workup

Imaging Studies

Weightbearing radiography of the feet and ankles is essential (see the images below). Radiographs should be inspected for evidence of degenerative arthritis, the positioning of the calcaneus, and forefoot alignment. A calcaneal pitch angle can be measured by drawing a line along the plantar aspect of the calcaneus and the ground. An angle greater than 30° is significant for hindfoot varus. The positioning of the first ray compared to the axis of the talus viewed on lateral radiographs determines if the first ray is plantarflexed.

Pes cavus with severe hindfoot involvement. Pes cavus with severe hindfoot involvement.
Pes cavus with plantarflexion of the first ray. Pes cavus with plantarflexion of the first ray.

Magnetic resonance imaging (MRI) of the spine should be performed if unilateral progressive cavus is present in a patient without a history of trauma.

Other Tests

After the initial evaluation, a neurologic consultation is recommended in order to determine the etiology. Electromyography (EMG) and nerve conduction studies are performed to evaluate for Charcot-Marie-Tooth (CMT) disease, polio, and other abnormalities that can cause muscle imbalances that lead to cavus deformities.

 

Treatment

Approach Considerations

The goal of treatment is to produce a plantigrade foot that allows even distribution of weight. Failure to maintain an asymptomatic plantigrade foot is an indication for surgery.

An absolute contraindication for surgery is poor vascularity. Revascularization should be performed before reconstruction if warranted. Ideally, the soft tissues around the ankle and foot should be intact, without excessive swelling or ulceration. If an ulcer is present, the wound should be healed before reconstruction in order to minimize infection risk.

The main controversy in the reconstruction of these deformities is whether to proceed with osteotomies and tendon transfers or arthrodesis. The current trend is to preserve the joints, if possible, and to perform an extensive arthrodesis as a salvage procedure.

Nonoperative Therapy

The goal of treatment is to allow the patient to ambulate without symptoms. The underlying cause must be identified to determine whether the disorder is progressive. The patient must understand the rationale for treatment and realize that surgical reconstruction does not provide a normal foot. 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 significant relief. Physical therapy to stretch tight muscles and strengthen weak muscles may provide early relief. Orthotics with extra-depth shoes to offload bony prominences and prevent rubbing of the toes may alleviate symptoms.[20] 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.[21, 22]

Surgical Therapy

Surgical decision-making requires a careful and complete examination of the foot and ankle, especially for rigidity, strength, and deformities.[23, 24, 25] The goal of surgery is to provide a plantigrade foot.

Surgical procedures can be broadly categorized into soft-tissue and bony procedures. No single procedure is appropriate for all patients; frequently, multiple individual procedures must be performed. Tendon transfers and osteotomies can provide correction of the deformity without requiring an arthrodesis; however, arthrodesis may be warranted if arthritic changes are observed in the joints or if complete muscle paralysis is present.[26] The most common procedures are discussed below.

Plantar fascia release

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. Techniques for stripping the fascia off the calcaneus and complete resection of the plantar fascia have been described.

As described by Mann,[27] plantar fascia release is initiated by placing the patient in a supine position, with external rotation of the leg so that the plantar fascia can be exposed. A thigh tourniquet is usually used; this avoids the external contraction of the leg (extrinsic) muscles associated with calf tourniquet use.

An oblique incision is made just distal to the weightbearing plantar fat pad of the heel and extended over the contracted plantar fascia. This protects against injury to the branches of the calcaneal nerve. The incision is deepened through the fat to the level of the plantar fascia. The plantar fascia and the fascia of the abductor hallucis are exposed.

The fascia is cut while tension is applied to the metatarsophalangeal (MTP) joints by dorsiflexion. A segment of the fascia is removed. If the fascia surrounding the abductor hallucis is tight, it is also released. The area is inspected for any tight bands that should be released.

The wound is sutured closed in the usual fashion. Postoperatively, the patient, with the foot in neutral position, is placed in a compressive dressing with a plaster splint. The cast remains in place for 4 weeks or longer, depending on whether other procedures are combined.

The complications of plantar fascia release include incomplete release and nerve injury.[28, 29]

Great toe Jones procedure

A great toe Jones procedure is performed for a cockup deformity or clawing of the great toe with associated weakness of the anterior tibialis.[30, 17] In this case, the extensor hallucis longus (EHL) has been recruited to assist in ankle dorsiflexion, which causes hyperextension at the MTP joint and hyperflexion at the interphalangeal (IP) joint. This procedure transfers the EHL to the neck of the first metatarsal, with arthrodesis of the IP joint to improve the dorsiflexion of the ankle and remove the deforming force at the MTP joint and hallux.

This procedure is initiated with the patient supine and under general or spinal anesthesia. The lower extremity is exsanguinated, and a thigh tourniquet is inflated.

An incision is started at the medial border of the distal phalanx and extended across the IP joint, curving proximally to the level of the first metatarsal neck. Dissection is carried down to the extensor mechanism. The EHL insertion on the base of the distal phalanx is freed.

The surfaces of the IP joint are prepared by removing the articulating cartilage with a saw and aligned in 5° of plantarflexion. A guide pin is placed from the arthrodesis site distally out the tip of the toe and then retrograde into the proximal phalanx. An incision is made over the guide pin at the tip of the toe. A cannulated 4.0 screw is placed across the arthrodesis site. A Kirschner wire (K-wire) can be used to augment the fixation if needed. The final fixation is usually placed after the tendon transfer has been completed to prevent loss of fixation.

A suture tag is placed in the EHL tendon. The neck of the first metatarsal is identified, and a drill hole large enough to accommodate the tendon is made from the medial side to the lateral side. A Swanson tendon passer is used to bring the tendon from lateral to medial through the drill hole. The tendon is sewn to itself, with the ankle in 15° of dorsiflexion.

The incision wounds are closed in layers, and a compressive dressing with a posterior splint in 10° of dorsiflexion is used. Casting is left in place for a total of 8 weeks, with weightbearing disallowed for the first 4 weeks.

The complication most commonly observed with the great toe Jones procedure is nonunion of the IP joint, which is often asymptomatic.[31]

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 spaces. 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.

Girdlestone-Taylor transfer

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

The patient is positioned supine with a tourniquet. A small transverse incision is made at the proximal flexion crease. Blunt dissection with a curved hemostat is performed down to the flexor tendon sheath.

The sheath is opened with a longitudinal incision, and the long flexor tendon is identified. The tendon is retracted, and a percutaneous flexor tenotomy is performed at the incision site at the base of the distal phalanx. The tendon retracts into the wound.

A dorsal longitudinal incision is made over the proximal phalanx. Dissection is carried down to the extensor hood. A curved hemostat is passed from the dorsal side to the plantar side, next to the bone, to avoid injury to the neurovascular bundle. The medial long flexor tendon is transferred medially, and the lateral tendon is transferred laterally. The tendons are sewn onto the extensor mechanism, with the toe in 20° of plantarflexion. A K-wire can be placed across the MTP joint and kept in place for 3 weeks to protect the repair.

The wounds are closed in the usual fashion, and the foot is placed in a postoperative shoe. The toe is taped in a slight plantarflexed position, which is maintained for 6 weeks. Motion through the MTP joint is allowed after 6 weeks.

Base of first metatarsal osteotomy

In patients with a fixed plantarflexed first ray, a base of the metatarsal closing wedge osteotomy corrects the deformity, which is especially observed in Charcot-Marie-Tooth (CMT) disease. This procedure is usually combined with a plantar fascia release in a mild deformity or a Jones procedure.[30, 32]

The patient is placed in a supine position under either general or regional anesthesia. A dorsal incision is made over the base of the first metatarsal extending proximally to the medial cuneiform. The osteotomy is located 1 cm distal to the first tarsometatarsal (TMT) joint. After determining the amount of bone to be removed with a closing wedge, a 3.5-mm drill hole is made 1 cm distal to the final osteotomy site.

The osteotomy is made parallel to the TMT joint but not through the plantar cortex. The next cut is made, removing the amount of bone needed to correct the deformity, and the wedge of bone is removed. The plantar cortex is cracked with manipulation, and the osteotomy is closed.

To verify the correction, plantar pressure is applied to the base of the fifth and first metatarsal heads. Equal pressure should be found at these points.

The 2.5-mm drill with the centering guide is placed in the previous drill hole and advanced. The drill hole is tapped, and the 3.5 cortical screw is placed.

The wound is closed in the usual fashion, and the patient is placed in a compressive dressing with a plaster splint. The casting is maintained for 8 weeks, with weightbearing disallowed for the first 4 weeks.

Midfoot osteotomy

Tarsal osteotomy has been described for deformities through the midfoot; however, these osteotomies require cutting through multiple joints. They are quite technically complex and are rarely performed.[33, 18, 34] Zhou et al reported good results from performing midfoot osteotomy combined with adjacent joint-sparing internal fixation to treat rigid pes cavus deformity.[35]

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.

Because there are other procedures that are frequently performed along with tenodesis, the patient is positioned supine with a bolster under the ipsilateral hip. An oblique incision is made just posterior to the peroneal tendons, with care taken to avoid damage to the sural nerve. The tendon sheath is identified and entered. The PL and PB tendons are identified, and a tenodesis is performed. The wound is closed in layers and immobilized in a cast.

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 (triplanar osteotomy). This procedure is usually combined with a plantar fascia release and, frequently, tendon transfer(s).

The patient is positioned supine with a bolster under the ipsilateral hip. A thigh tourniquet is used.

An oblique incision is made just posterior to the fibula and posterior to the peroneal tendons. Careful dissection is carried down to the calcaneus to avoid the sural nerve. Subperiosteal dissection is performed on the lateral calcaneus with an elevator. The posterior facet is palpable and verified under image to prevent violation of the subtalar joint.

An oblique cut is made 1 cm posterior to the posterior facet. The cut does not penetrate the medial cortex. A second cut can be made to create a V-type cut, so that the wedge of bone can be removed laterally. The medial cortex is penetrated carefully to avoid injury to the neurovascular bundle. If a closing wedge osteotomy is not needed or is combined with displacement, then the soft tissues are stretched medially with a laminar spreader. The osteotomy can then be displaced laterally or superiorly.

The osteotomy is usually fixed with a cannulated screw placed from the posterior side to the anterior side. Staples or large Steinmann pins can be used.

The wounds are closed in the usual fashion and placed in a compressive dressing with a plaster splint. A cast is placed when the swelling subsides. The patient is nonweightbearing for the first 4 weeks and then limited to partial weightbearing for another 4 weeks.

Beak triple arthrodesis

The Siffert beak triple arthrodesis corrects pes cavus deformities through wedge resection and a triple arthrodesis.[36] 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, cuboid, and cuneiforms to improve forefoot cavus deformities. This procedure is complex and technically demanding.

The patient is positioned supine with a bolster under the ipsilateral hip. A thigh tourniquet is used. An incision is made laterally from the tip of the fibula to the base of the fourth metatarsal.

The extensor digitorum brevis (EDB) is removed from its origin on the sinus tarsi and reflected distally. The subtalar and calcaneocuboid joints are exposed, and the lateral talonavicular joint may be visualized through the lateral wound.

A medial approach is made from the tip of the medial malleolus to the naviculocuneiform joint. The capsule of the talonavicular joint is exposed with care so as to avoid excess dissection dorsally and to preserve blood flow.

The first cut involves the posterior facet of the subtalar joint, with resection of 3-5 mm of bone laterally.

From the medial incision, a segment of the plantar two thirds of the talus is resected to a depth of 1 cm; the dorsal one third of the talus is left intact. The dorsal aspect of the navicular is removed so that the navicular can be placed against the talus.

The calcaneocuboid joint is prepared by removing the joint surfaces with a saw to correct the abduction-adduction alignment in the foot.

The arthrodesis sites are fine-tuned for position and apposition. The sites are then fixed in the following order: (1) subtalar, (2) talonavicular, and (3) calcaneocuboid. They are fixed with cannulated screws, staples, plates, Steinmann pins, or a combination of these.

The wounds are closed in the usual fashion, and a compressive dressing is applied with a posterior plaster splint. Postoperatively, casting is maintained for 6 weeks, during which weightbearing is disallowed; after this period, the patient is limited to partial weightbearing for 4 weeks.

Complications

The complications of these procedures include the following:

  • Nonunion
  • Malunion
  • Infection
  • Undercorrection
  • Overcorrection
  • Recurrence of the deformity
  • Progression of the deformity
  • Nerve injury
  • Continued pain

For progressive disorders, deformities can recur; patients need to be educated about this possibility before the initial surgery.