Pes cavus, also known as a high arch, is a human foot type in which the sole of the foot is distinctly hollow when bearing weight. That is, there is a fixed plantar flexion of the foot. A high arch is the opposite of a flat foot and is somewhat less common.
Pes cavus is an orthopedic condition that manifests in both children and adults. Pes cavus and pes cavovarus are often used interchangeably as the most common manifestation of the cavus foot is the cavovarus presentation. Pes cavus is a deformity that is typically characterized by cavus (elevation of the longitudinal plantar arch of the foot), plantar flexion of the first ray, forefoot pronation, and valgus, hindfoot varus, and forefoot adduction. Pes cavus is frequently a manifestation of an underlying neurological process, but there has been literature that discusses a subset of patients in whom a more subtle form of the cavus foot may present without an underlying disease process.
Types of Pes Cavus
The term pes cavus encompasses a broad spectrum of foot deformities. Three main types of pes cavus are regularly described in the literature: pes cavovarus, pes calcaneocavus, and ‘pure’ pes cavus. The three types of pes cavus can be distinguished by their etiology, clinical signs, and radiological appearance.[rx][rx]
- Pes cavovarus – the most common type of pes cavus, is seen primarily in neuromuscular disorders such as Charcot-Marie-Tooth disease and, in cases of unknown etiology, is conventionally termed ‘idiopathic’.[rx] Pes cavovarus presents with the calcaneus in varus, the first metatarsal plantarflexed, and a claw-toe deformity.[rx] Radiological analysis of pes cavus in Charcot-Marie-Tooth disease shows the forefoot is typically plantarflexed in relation to the rearfoot.[rx]
- In the pes calcaneocavus foot – which is seen primarily following paralysis of the triceps surae due to poliomyelitis, the calcaneus is dorsiflexed and the forefoot is plantarflexed.[rx] Radiological analysis of pes calcaneocavus reveals a large talocalcaneal angle.
- In ‘pure’ pes cavus – the calcaneus is neither dorsiflexed nor in varus and is highly arched due to a plantarflexed position of the forefoot on the rearfoot.[rx] A combination of any or all of these elements can also be seen in a ‘combined’ type of pes cavus that may be further categorized as flexible or rigid.[rx] Despite various presentations and descriptions of pes cavus, not all incarnations are characterized by an abnormally high medial longitudinal arch, gait disturbances, and resultant foot pathology.
Causes of Pes Cavus
Pes cavus is seen in both adult and pediatric populations. When it is found to be bilateral, it is often from a hereditary or congenital source. A unilateral presentation is more typical for post-traumatic conditions.[rx] In the absence of such a cause, a unilateral presentation of pea cavus mandates MRI of the brain and spinal cord, to exclude treatable progressive lesions such as a brain tumor or, during growth, a tethered spinal cord. There are four primary causes of the cavovarus foot.[rx][rx][rx][rx]
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Neurologic conditions – hereditary motor and sensory neuropathies (HMSN), cerebral palsy, post-stroke symptoms, anterior horn disease, spinal cord lesions, poliomyelitis, myelomeningocele, polyneuritis syndromes, Parkinson disease, Huntington chorea, Friedreich ataxia, amyotrophic lateral sclerosis, leprosy, Roussy-Levy syndrome, Stumpell-Lorrain disease, Pierre-Marie hereditary
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Traumatic – compartment syndrome, talar neck malunion, peroneal nerve injury, knee dislocation, scar tissue, burns, vascular lesions, hindfoot instability, tibial fractures (distal), or calcaneal malunion
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Post-traumatic bone deformities or ligamentous imbalance or instability often lead to a deformity in this post-traumatic setting.
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Untreated or undertreated clubfoot
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Idiopathic or other causes include tarsal coalition, rheumatoid arthritis, ankle osteoarthritis, plantar fibromatosis, varus subtalar joint axis, diabetic foot syndrome. The subtle cavus foot is often categorized within the idiopathic group.
Symptoms of Pes Cavus
Cavus foot, even subtle deformity, can cause various problems throughout the foot and ankle. Metatarsalgia due to forefoot overload is related to the combined effect of cavus foot and tight heel cord. When examining a patient with metatarsalgia, cavus foot should be in the list of differential diagnoses along with Morton’s neuroma and long metatarsals. Overload on the 1st metatarsal head can lead to sesamoiditis or sesamoid fractures. Overload on the lateral border can result in a stress fracture of the 5th metatarsal. Stress fracture of the 5th metatarsal is difficult to treat without addressing the underlying cavus deformity.
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Clinical manifestations associated with a cavus foot.
| Forefoot and Midfoot |
| Metatarsalgia |
| Callus under 1st, 5th metatarsal heads |
| Morton’s neuroma |
| Sesamoid problems (sesamoiditis, chondromalacia, avascular necrosis) |
| Stress fracture of metatarsal bones |
| Metatarsus adductus |
| Midfoot arthritis |
| Ankle and hindfoot |
| Plantar fasciitis |
| Achilles tendinitis |
| Chronic lateral ankle instability |
| Subtalar instability |
| Peroneal tendon problems (tear or split, rupture, tendinopathy) |
| Enlarged or posteriorly placed distal fibular |
| Recurrent dislocation of the peroneal tendons |
| Painful os perineum syndrome |
| Painful Haglund deformity |
| Varus ankle arthritis |
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Reduced shock absorption due to rigid hindfoot and tight heel cord can lead to plantar fasciitis or Achilles tendinitis. Haglund deformity can become symptomatic more easily if the heel is in varus because the posterior superior calcaneal tuberosity will become more prominent. Rigid joints can progress to joint destruction and develop arthritis over time.
Chronic lateral ankle instability and recurrent sprain are inevitable in a patient with a cavus foot. Prolonged lateral overload and recurrent sprain can lead to peroneal tendon problems. Any attempt to repair the lateral ligamentous problems will not be successful if the bony structure has remained in varus. If left untreated, prolonged cavus foot will eventually lead to varus ankle osteoarthritis.
Diagnosis of Pes Cavus
The following radiographic features can help in considering the diagnosis of a cavus foot [rx, rx, rx, rx] Increased calcaneal pitch (angle between a line along the undersurface of the calcaneus and the floor; normal is <30°). Increased Memory angle (due to the plantarflexed first metatarsal, the angle between a line drawn along the axis of the first metatarsal and that of the talus is increased. Normal is 0 ± 5°)
Increased Hibbs angle (angle between a line through the axis of the calcaneus and the first metatarsal; normal is <45°; cavus is near 90°). Increased navicular height. Posterior position of the fibula (the fibula appears more posterior to the tibia than normal due to the varus hindfoot position and external rotation of the lower limb.). Subtalar view (Due to the inversion of the hindfoot, the posterior facet of the subtalar joint is clearly visible in a lateral foot radiograph).
In order to correctly measure some of the angles mentioned above, true dorsoplantar and lateral weight-bearing foot radiographs are required. However, when the deformity is severe, the talus and calcaneus tilt into varus, making it impossible to draw a correct axis of the bone. Therefore, the reference values mentioned above are to be used as guidelines rather than definitive diagnostic criteria.
The Coleman block test is a critical portion of the examination as one of the major goals of the physical exam is to determine the rigidity of the deformity.[rx] The test was first described in 1977 and has remained an essential tool for the evaluation of the cavus foot.[rx]
The Coleman block test is performed by placing a roughly 1-inch block (or 2.5 cm) or a book under the lateral side of the forefoot and heel. The first metatarsal head should hang off the edge of the block, thus removing its effects on the tripod. The examiner must then evaluate the hindfoot to determine if removing the first metatarsal’s deforming effects has allowed the hindfoot to correct from varus to valgus. If the hindfoot varus does not correct, the deformity is rigid and fixed, and this has different surgical implications than a flexible deformity. If the block test restores hindfoot valgus, then the deformity is flexible and driven by the forefoot.
Evaluation should include palpation along the lesser metatarsals and fifth metatarsal for signs and symptoms of stress fractures. Examination of the ankle for stability, joint tenderness, and peroneal tendinopathy should also be undertaken. Anterior ankle pain is common due to the impingement of the relatively dorsiflexed talus.
A major clinical sign of the subtle cavus foot is the “peek-a-boo” heel first described by[rx] It has been described as the ability to see the heel pad easily from the front with the patient standing and both feet pointing ahead. In the normal foot, the heel pad should not be visible when viewed from the front due to the natural valgus alignment of the hindfoot.[rx]
Evaluation
Plain film radiographs are the first investigation for the cavus foot. Recommended views include[rx]:
- Weight-bearing views of the foot and ankle
- Calcaneal axial view (others have suggested that the Colby view may be more helpful in the evaluation of hindfoot alignment).[rx]
- A standard evaluation for fractures, dislocations, and degenerative changes should begin any radiographic assessment, other specific lines, geographic measurements, and angles can help the clinician determine the relative position of the foot to its other components. Some of the more commonly used examples are listed below:
- One can determine the presence of cavus by evaluating the relative position of the inferior aspect of the medial cuneiform and the fifth metatarsal base on a lateral x-ray of the foot. When the 5th metatarsal base is closer to the floor, the foot is in cavus.
- Mary’s line (a line measured along the long axis of the talus and first metatarsal) is normally zero, but in the cavus foot, the first metatarsal is plantarflexed, increasing the angle. A mild cavus foot may have Mary’s angle of five to ten degrees, with severe cavus feet having angles greater than twenty degrees.[rx]
- A Hibb angle may also be used. This is a measurement between the longitudinal axis of the calcaneus and the first metatarsal. Values in normal feet are generally less than 45 degrees. In patients in pes cavus deformities, the angle is often greater than 90 degrees.[rx]
- A talocalcaneal angle on the AP radiograph will show a divergent talus and calcaneus in a normal foot with an angle of twenty to forty degrees. When the angle is decreased, this indicates that the talus and calcaneus are more parallel, and the foot is in cavus.[rx]
- The Djian-Annonier angle (the angle of the medial arch) is widely used in France and is found to be less than one-hundred and twenty degrees in the cavus foot.[rx] This angle is measured from where the calcaneus rests against the ground, to the talonavicular joint at the apex and to the medial sesamoid where it contacts the ground again.
Other Imaging
- Computed tomography (CT) scans may also be performed to allow for evaluation of the joints for arthrosis for surgical planning and a complete evaluation of the hindfoot position.[rx]
- Magnetic resonance imaging has been described for the evaluation of the lateral ligamentous complex, peroneal tendon pathology, osteochondral lesions, and evaluation of fifth metatarsal base fractures.[rx]
- In cases of suspected HMSNs, patients may benefit from evaluation by a neurologist for possible electromyogram and/or genetic testing.[rx]
- Unilateral pes cavus without obvious explanation should prompt MRI of the brain and spinal cord.
Treatment of Pes Cavus
Nonsurgical Treatment
Patients with milder symptoms associated with a cavus deformity can benefit from conservative treatment consisting of gastrocnemius muscle stretching exercise and specialized foot orthotics. The aim of applying an orthotic is to realign the hindfoot correctly to offload the lateral border of the foot. Therefore, an ideal orthotic for a subtle cavus foot should support the lateral hindfoot and midfoot with a wedge [rx]. Medial arch support should be minimized since it can further tilt the foot in supination [rx].
Surgical Reconstruction
When considering an operative treatment for a cavus foot, the goal is to obtain a stable plantigrade foot with the preservation of joints if possible. In order to do that, one should recognize the muscle imbalance and understand the structural alterations in the foot. The foot will not be balanced with any uncorrected structural deformity and the deformity will recur if the foot is not balanced. So, for any cavus foot, one has to correct the muscle imbalance and correct any structural deformity.
Since every deformity is unique, there is no such thing as a standard protocol that can be applied universally. Instead, there is a list of many procedures and surgical options that we can choose from to optimally reconstruct each cavus foot.
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List of surgical procedures for cavus foot.
| Correction of the structural deformity |
| Soft tissue procedures |
| Achilles tendon lengthening |
| Plantar fascia release |
| Abductor hallucis fascia release |
| Deltoid ligament release |
| Lateral ankle ligament reconstruction |
| Osteotomies |
| First metatarsal dorsiflexion osteotomy |
| Midtarsal closing wedge osteotomy |
| Calcaneal valgizational osteotomy |
| Arthrodesis |
| Double or Triple fusion |
| First tarsometatarsal fusion |
| Naviculocuneiform arthrodesis |
| Correction of dynamic muscle imbalance |
| Tendon transfers |
| Peroneus longus tendon transfer to peroneus brevis |
| Posterior tibial tendon transfer to dorsum of foot |
| Anterior tibial tendon transfer to the middle of the foot |
| Extensor hallucis longus transfer to 1st metatarsal (Jones procedure) |
| Correction of the structural deformity |
| Correction of claw toes |
| Soft tissue release |
| Resection arthroplasty |
| Proximal interphalangeal joint fusion |
| Girdlestone Taylor transfer |
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Soft Tissue Releases
Prolonged cavovarus deformities are almost always accompanied by tight heel cord and contracted medial and plantar soft tissues. Since it is impossible to correct structural deformity in the presence of contracted soft tissues, the release of tight soft tissues must be preceded to any other procedures.
Tight Achilles tendon can be lengthened by percutaneous triple hemisection, open Z-plasty, or by gastrocnemius recession. Silfverskiold test is useful to determine the components of Achilles tendon that require lengthening. Once the Achilles tendon is lengthened, a more accurate assessment of the residual varus deformity becomes possible.
Plantar fascia should be completely released. It can be performed through a 3 cm long incision over its calcaneal insertion. In severe cavus feet, the abductor hallucis fascia may also require a release, which can be performed through the same incision. Care should be exerted not to injure the medial calcaneal branch of the tibial nerve as well as the nerve branch that inserts to the abductor hallucis muscle.
In severe cavovarus cases, additional release of posteromedial structures including flexor hallucis longus, flexor digitorum longus, the posterior tibialis tendon can also be necessary. Release of the deltoid ligament can be performed if there is a talar tilt in the ankle joint due to deltoid contracture.
Bony Reconstruction
Correction of structural deformity requires either osteotomy or arthrodesis. If the hindfoot is flexible, determined by the positive Coleman block test, an osteotomy can realign the cavovarus without scarifying the joint. Whenever possible, osteotomies are preferred over fusions. However, if the hindfoot varus is rigid, arthrodesis may be inevitable.
A positive Coleman block sign implies that the hindfoot varus is due to the plantarflexed 1st ray and the hindfoot is flexible. Therefore, removing the deforming force by elevating the first ray must be performed. It can be achieved by a dorsiflexion osteotomy at the base of the first metatarsal. A dorsal wedge is removed at a point 10mm distally from the first tarsometatarsal joint. If the apex of the deformity is more proximal, arthrodesis of the 1st tarsometatarsal joint or closing wedge osteotomy at the medial cuneiform can be considered.
If hindfoot varus is fully corrected with 1st metatarsal osteotomy, then calcaneal osteotomy is not necessary. However, if there is residual varus after the dorsiflexion osteotomy, or if the Coleman block did not completely correct the hindfoot varus, a calcaneal osteotomy must be done. For a mild varus, a Dwyer closing wedge osteotomy [rx] may be sufficient. For a greater amount of correction, lateralization osteotomy is necessary. An oblique osteotomy has the advantage of three-dimensional correction as the posterior fragment can be rotated, translated, and elevated. Rotation can be achieved with additional resection of a lateral based wedge. Elevation of the posterior fragment is helpful to decrease the calcaneal pitch. A Z osteotomy [rx] is another powerful tool to correct the heel varus. The osteotomy primarily allows translation, but a little bit of rotation can be added by removing small wedges. Since the center of rotation is more anterior, the Z osteotomy allows a greater degree of correction compared to Dwyer osteotomy.
Salvaging joints wherever possible is beneficial because it allows more flexibility and shock absorption. However, rigid or severe cavus foot can only be reconstructed using arthrodesis. For a triple arthrodesis, the subtalar, talonavicular, and calcaneocuboid joints are denuded and fixed in a mild heel valgus position. The forefoot should be supinated through the Chopart joint [rx]. When performing a triple arthrodesis, the cuboid can slide slightly beneath the calcaneus due to the natural shape of the calcaneocuboid joint. This causes a painful bony bump on weight-bearing. To avoid this, it is useful to flat cut the calcaneocuboid joint with a saw. Excluding the calcaneocuboid joint in a triple fusion is also feasible since the calcaneocuboid joint is rarely arthritic. This is also beneficial because it reduces the potential of problematic nonunion of the calcaneocuboid joint.
Muscle Balancing
If the deformity is originated from or related to any kind of muscle imbalance, a tendon transfer is always necessary. Without well-balanced muscle power, the deformity will recur and the correction will eventually fail
Peroneus longus transfer to brevis is the most commonly performed tendon transfer. Since peroneus longus plantar flexes the 1st metatarsal, removing this deforming force is essential in preventing the recurrence. It is also beneficial because the transferred peroneus longus tendon augments the peroneus brevis, which is frequently weakened or problematic. If the peroneus brevis is severely torn or degenerated, the pathologic portion should be repaired or excised before the transfer.
Posterior tibial tendon produces an unopposed pull in the presence of the peroneus brevis dysfunction. As a result, foot inversion and progressive contracture of the medial soft tissues will develop. Therefore, the goal of the posterior tibial tendon transfer is to weaken the deforming power and to strengthen the deficient function of the foot. The transferred posterior tibial tendon is inserted into one of the cuneiforms, where it functions as an ankle dorsiflexor.
In less severe deformities, the anterior tibial tendon can be transferred laterally to the middle cuneiform. Lateralizing the anterior tibial tendon reduces the supination vector while maintaining the dorsiflexion power. If the strength of the anterior tibial muscle is maintained, an isolated transfer is performed. If the tendon is weak, augmentation with the simultaneous transfer of the extensor digitorum longus can be considered [rx].
Besides tendon transfers, repairing or augmenting the lateral ankle ligaments is frequently performed since lateral ankle instability is almost always accompanied in a cavus foot. Ligament repair with extensor retinaculum augmentation is the procedure of choice. Peroneus transfer to brevis also augments the lateral stability.
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