Pediatric Annals

Special Issue Article 

Evaluating the Cavus Foot

Ananth S. Eleswarapu, MD; Bakhtiar Yamini, MD; Robert J. Bielski, MD

Abstract

The cavus foot is a deformity characterized by abnormal elevation of the medial arch of the foot. Unique among foot deformities, cavus typically occurs secondary to a spinal cord or neuromuscular pathology, with two-thirds of patients having an underlying neurologic diagnosis. Thus, recognition of cavus foot and appropriate evaluation are essential in the primary care setting. Patients may present with unstable gait, frequent ankle sprains, or pain along the metatarsal heads or the lateral border of the foot. The diagnosis can be confirmed with a lateral weight-bearing radiograph, with several key measurements defining a pes cavus alignment. A thorough history and physical examination should be performed to look for possible secondary causes. The first step in the treatment of cavus deformity is to address the underlying cause. After that, a variety of treatment options are available to alleviate the pain and dysfunction caused by this deformity. [Pediatr Ann. 2016;45(6):e218–e222.]

Abstract

The cavus foot is a deformity characterized by abnormal elevation of the medial arch of the foot. Unique among foot deformities, cavus typically occurs secondary to a spinal cord or neuromuscular pathology, with two-thirds of patients having an underlying neurologic diagnosis. Thus, recognition of cavus foot and appropriate evaluation are essential in the primary care setting. Patients may present with unstable gait, frequent ankle sprains, or pain along the metatarsal heads or the lateral border of the foot. The diagnosis can be confirmed with a lateral weight-bearing radiograph, with several key measurements defining a pes cavus alignment. A thorough history and physical examination should be performed to look for possible secondary causes. The first step in the treatment of cavus deformity is to address the underlying cause. After that, a variety of treatment options are available to alleviate the pain and dysfunction caused by this deformity. [Pediatr Ann. 2016;45(6):e218–e222.]

Flat foot is a common problem encountered in the pediatrician's office, but the vast majority of flat feet are not associated with any serious medical issues. In contrast, the high arched or cavus foot is frequently associated with neuromuscular problems. Thus, recognition of cavus foot and appropriate evaluation are essential in the primary care setting.

Illustrative Case

A 14-year-old girl presented with a high-arched left foot and weakness of the left leg, both of which had been slowly growing worse for months. In addition, she had developed low back pain in the past few weeks prior to presentation but denied upper extremity symptoms or bowel/bladder dysfunction. On examination she was noted to have a cavovarus deformity of the left foot, with a high arch, plantar-flexed first ray, and varus alignment of the hindfoot (Figure 1). She was also noted to have atrophy of the left calf muscles. X-rays of the left foot showed pes cavus alignment of the foot, with no arthritis (Figure 2). X-rays of the spine showed scoliosis, with a 33-degree left lumbar curve. Given the unilateral high arch, muscle atrophy, and scoliosis, the patient was referred for a magnetic resonance imaging (MRI) scan of the spine, showing an intramedullary mass at the T12 level (Figure 3). The patient was referred to neurosurgery for open biopsy, which showed a low-grade pilocytic astrocytoma. Given the location of the lesion, the decision was made not to pursue surgical resection, as the risk of paraplegia or loss of bowel/bladder control would be high. The patient was instead treated with decompressive laminectomy and proton-beam therapy. Her flexible foot deformity was managed with a plantar fascia release, with the knowledge that further procedures may be needed in the future if her deformity persisted or worsened.


            Clinical image of a cavus foot.

Figure 1.

Clinical image of a cavus foot.


            Lateral weight-bearing radiograph showing cavus foot alignment.

Figure 2.

Lateral weight-bearing radiograph showing cavus foot alignment.


            Sagittal magnetic resonance image showing intramedullary lesion of the spine at T12 level.

Figure 3.

Sagittal magnetic resonance image showing intramedullary lesion of the spine at T12 level.

Cavus Foot

Cavus foot describes a set of foot deformities characterized by an abnormal elevation of the medial arch of the foot.1,2 Although most foot deformities, such as flat foot or bunion, result from intrinsic foot pathology, cavus deformity is unique in that it commonly occurs secondary to a spinal cord or neuromuscular pathology1,3 (Table 1). Up to two-thirds of patients with symptomatic cavus foot have an underlying neurologic disorder, the most common of which is Charcot-Marie-Tooth (CMT) disease.1–4


            Differential Diagnosis of Cavus Foot Deformity

Table 1:

Differential Diagnosis of Cavus Foot Deformity

Mechanics of the Cavus Foot

Cavus foot typically results from an imbalance between the muscle forces acting upon the foot.3 The most common form of cavus deformity is pes cavovarus. In the cavovarus foot, the first metatarsal is plantarflexed, resulting in elevation of the medial arch of the foot.3 Muscles that dorsiflex the first metatarsal, such as tibialis anterior, are weak and overwhelmed by plantarflexors, such as posterior tibialis, peroneus longus, and the intrinsic muscles of the foot. An abnormally high arch results in inversion of the heel into a varus position and shifts weightbearing to the lateral surface of the foot. Patients may present with unstable gait, frequent ankle sprains, and calluses along the metatarsal heads and lateral surface of foot.1 With time, the plantar fascia tightens, locking the arch in an elevated position.3

In patients with cavovarus foot, the plantar fascia is tight and the foot is in a rigidly locked position throughout the gait cycle, which prevents stress distribution and predisposes the patient to foot pain and early arthrosis.2,3 Particularly affected are runners with cavovarus foot, who may present with pain over the metatarsal heads, plantar fasciitis, arch pain, and iliotibial band syndrome.3

Clinical Presentation

The patient with a cavus foot may be asymptomatic, with the parents bringing the patient in simply for evaluation of a high arch; however, foot pain is a common complaint. Patients may initially complain of pain in the arch, but as the deformity progresses pain will be seen over the metatarsal heads (or “ball” of the foot) and the heel because more pressure is placed on these areas in the cavus foot. The patient may have calluses over the heel and the metatarsal heads because of unequal weight distribution. As the heel goes into more varus, the patient may experience recurrent ankle sprains. It must be noted that the absence of pain does not rule out serious underlying pathology.

History

The goal of taking a patient history in the evaluation of patients with cavus foot is to look for possible secondary causes of the deformity. A birth and developmental history should be taken to look for signs of cerebral palsy. In addition, patients and family should be questioned about a history of clubfoot, as residual clubfoot can present as a cavus deformity. A family history should be taken to screen for history of CMT. The physician should ask if the mother or father have high arches.

Patients should also be asked about sensory changes, proximal muscle weakness, and bowel/bladder symptoms, as these may point to a spinal cord etiology.3 A unilateral cavus foot or progressively worsening elevation of the arch is particularly concerning for spinal cord pathology and merits evaluation with MRI. Patients should be questioned about a history of trauma to the extremity, as the chronic sequelae of compartment syndrome and peroneal nerve injury can all present with a cavus deformity to the foot, although this is probably less likely in the pediatric population.5 Cases in which no underlying cause of cavus deformity are found are termed as idiopathic; this, however, should remain a diagnosis of exclusion, made only after a thorough search for secondary causes has been performed.5

Physical Examination

A thorough physical examination is essential in the evaluation of cavus foot, both to identify secondary causes as well as to guide management of the deformity. Visual inspection of the back should be performed, looking for scoliosis, a hairy patch, or sacral dimpling, any of which may point to a spinal etiology of the cavus deformity.3 In addition, patients with CMT may present with toe clawing, hand muscle atrophy, sensory loss, scoliosis, hyporeflexia, or painful hip dysplasia.3,4 The common pattern in CMT is for symptoms to begin distally and progress proximally as the disease becomes more advanced.4

It can be helpful to examine the feet of both parents. It is not unusual to find that one of the parents has a cavus foot as well. This may be a sign that this is a “benign” idiopathic cavus. However, we have cared for children with CMT with at least one parent who had lived with a cavus foot for most of his or her life, unaware of the effects of CMT. Although the most common inheritance pattern in CMT is autosomal dominant, X-linked or autosomal recessive inheritance can also be seen in certain variants.4

Often times, a cavovarus alignment may be subtle and not immediately obvious on inspection of the foot. If a cavovarus deformity is still suspected (on the basis of clues from patient history, such as frequent ankle sprains, lateral foot pain/callosities, unstable gait, or ill-fitting shoes), patients can be evaluated for the presence of a “peek-a-boo” heel (Figure 4). The patient first faces the examiner and stands with feet parallel and 6 inches apart. In a normal foot, the medial aspect of the heel should not be visible when the foot is viewed from the front. When there is a varus alignment, the heel sits medial to the ankle and the medial aspect of the heel is visible from the front. This is described as a “peek-a-boo” heel and can be a sign of a subtle cavus deformity.5 Care should be taken to ensure that the foot is not externally rotated at the time of examination, as this may cause a false-positive “peek-a-boo” sign.


            Clinical image showing a “peek-a-boo heel” (medial aspect of the heel is visible when the foot is viewed from the front).

Figure 4.

Clinical image showing a “peek-a-boo heel” (medial aspect of the heel is visible when the foot is viewed from the front).

The natural history of the cavus foot in CMT is to begin as a flexible deformity during childhood and gradually progress to a rigid fixed deformity.6 Flexible deformities are more likely to respond to conservative treatments such as orthotics, and, if surgery is required, can often be treated with soft tissue releases or tendon transfers. Rigid deformities, on the other hand, will often require osteotomies or arthrodesis to realign the foot. A useful test to determine if the hindfoot is flexible is the Coleman block test (Figure 5). A 1-inch block is placed under the heel and lateral forefoot, with the medial two toes allowed to fall off the block. The examiner stands behind the patient and observes the alignment of the heel. If the heel corrects to neutral, a flexible deformity is present. If the heel remains in varus, the hindfoot deformity is rigid.5


            (A) Clinical image of cavus foot showing varus deformity of heel (the weight-bearing surface of the heel is angled inward relative to the axis of the tibia). (B) Clinical image of the Coleman block test (varus deformity of the heel reduces when the lateral surface of the foot is elevated on a block, showing that the deformity is flexible).

Figure 5.

(A) Clinical image of cavus foot showing varus deformity of heel (the weight-bearing surface of the heel is angled inward relative to the axis of the tibia). (B) Clinical image of the Coleman block test (varus deformity of the heel reduces when the lateral surface of the foot is elevated on a block, showing that the deformity is flexible).

The toes should also be examined in patients with cavus deformity. Weakness of foot intrinsic muscles can result in claw-toe deformities3 (Figure 6).


            Clinical image showing clawing of the lesser toes.

Figure 6.

Clinical image showing clawing of the lesser toes.

Finally, the patient's gait should be observed. Patients with underlying neurologic disorder may present with a foot drop and “marionette” gait, in which they elevate the pelvis on the affected side to lift the dropped foot through the swing phase.3,5 These patients would benefit from an ankle-foot orthosis to assist with ambulation. Patients with hip pathology as a result of CMT may also present with a Trendelenburg gait, which should prompt clinical and radiographic evaluation of the hips and pelvis.3

Radiographic Evaluation

The primary care physician may prefer to have the orthopedist order radiographs, but we will briefly describe the radiographic examination of a patient with a cavus foot. Radiographs should be taken with the patient bearing weight on the foot. There are several key radiographic measurements made on the lateral view that help define the cavovarus deformity. Meary's angle is the angle formed between the long axis of the talus and the long axis of the first metatarsal (Figure 7A). This angle should be 0 degrees in a normal foot; angles >5 degrees indicate cavus alignment.3 Calcaneal pitch is the angle between a line drawn along the undersurface of the calcaneus and the floor (Figure 7B). Calcaneal pitch >30 degrees is also associated with cavus foot. A weight-bearing lateral radiograph of a normal foot (Figure 8) is provided for comparison.


            (A) Lateral weight-bearing radiograph of the foot showing Meary's angle. (B) Lateral weight-bearing radiograph of the foot showing calcaneal pitch.

Figure 7.

(A) Lateral weight-bearing radiograph of the foot showing Meary's angle. (B) Lateral weight-bearing radiograph of the foot showing calcaneal pitch.


            Lateral weight-bearing radiograph showing a normal foot.

Figure 8.

Lateral weight-bearing radiograph showing a normal foot.

Further Diagnostics

CMT disease is the most common neurologic condition found in patients with bilateral cavus foot, but these patients may not show obvious neurologic deficits at the time of initial presentation.3 For this reason, it may be necessary to obtain nerve conduction and electromyography studies in patients presenting with cavus foot without a known etiology. Referral to a pediatric neurologist is often needed to definitively make the diagnosis. DNA testing can be done to help make the diagnosis, but because so many genes are now linked to CMT, a single laboratory testing cannot typically screen for all the possible genetic combinations.4

Patients presenting with unilateral or asymmetric cavus, with rapidly progressing deformity, or with neurologic deficits should have radiographic evaluation of the spine. Initial evaluation can begin with radiographs, which may show evidence of scoliosis, dysraphism, or erosive changes due to tumor. Plain radiographs often do not demonstrate the tumor. Therefore, there should be a low threshold to order a spinal MRI in these patients, as cavus foot can be caused by spinal cord lesions or intramedullary tumors that may not be seen on plain radiographs. MRI of the whole spine should be performed, and done with and without gadolinium contrast.7 Again, in these situations, prompt referral to an orthopedist or neurologist is recommended.

The most common presenting symptom in children with a spinal cord tumor is neck and back pain, but its absence does not rule out the presence of a tumor.7 Back pain that wakes children at night should be carefully evaluated.7 In younger children who cannot verbalize pain, motor delay, early handedness, head tilt, or abdominal complaints may be presenting symptoms.7 The patient should be questioned about bowel and bladder dysfunction as well. Pediatric spinal cord tumors are often associated with spinal deformities such as kyphosis or scoliosis. Astrocytomas are the most common tumor of the pediatric spine, comprising 35% of intramedullary tumors.7

Management

Again, we stress that the first principle in the management of cavus foot deformity is to identify and treat the underlying cause.3 Once that has been done, there are several options available to alleviate symptoms. Patients with mild and flexible deformity can be treated initially with nonoperative measures. Custom orthotics can help relieve pain. Plantar fascia stretching can help to loosen the medial arch. Patients can also be cautioned to avoid high-impact exercises that put excess stress on the foot.

Patients with symptoms that persist despite nonoperative management, or those with rigid symptomatic deformities, are appropriate for surgical management. There are a myriad of surgical treatments available, and the treatment plan must be tailored to the individual patient. The key considerations for the clinician are the age and functional status of the patient, whether the deformity is flexible or rigid, and whether the underlying condition is progressive or nonprogressive. In general, flexible deformities can be treated with soft tissue procedures, whereas fixed deformities require osteotomy. If there is severe deformity or arthrosis present, an arthrodesis (fusion) may be needed to restore alignment and alleviate pain.3 This should typically not be performed until patients have reached skeletal maturity.3 As with all joint fusions, patients are at risk of developing degeneration of adjacent joints over time.

The initial surgical treatment in young patients with flexible deformity is often a plantar fascia release, followed by postoperative serial casting to help correct the cavus deformity. Tendon transfers can also be done to help rebalance the foot. Patients with progressive underlying conditions who have soft tissue procedures performed early in the disease course should be cautioned that further procedures may be required as the deformity progresses.

Conclusion

Cavus foot is a deformity characterized by abnormal elevation of the medial arch of the foot. Patients may present with unstable gait, frequent ankle sprains, and callosities on the metatarsal heads and lateral border of the foot. An underlying neuromuscular pathology is present in two-thirds of patients with cavus foot, and a comprehensive history and physical examination should be performed to search for an underlying etiology. The first principle of treatment is to address the underlying cause. A variety of treatments are available to alleviate symptoms, ranging from conservative (orthotics, shoe modification) to surgical management.

In the patient discussed in the illustrative case, unilateral presentation and rapid worsening of the deformity, along with muscle atrophy, all pointed to a neuromuscular problem that required prompt evaluation and treatment.

References

  1. Mosca VS. The cavus foot. J Pediatr Orthop. 2001;21(4):423–424. doi:10.1097/01241398-200107000-00001 [CrossRef]
  2. Aminian A, Sangeorzan BJ. The anatomy of cavus foot deformity. Foot Ankle Clin North Am. 2008;13:191–198. doi:10.1016/j.fcl.2008.01.004 [CrossRef]
  3. Schwend RM, Drennan JC. Cavus foot deformity in children. J Am Acad Orthop Surg. 2003;11(3):201–211. doi:10.5435/00124635-200305000-00007 [CrossRef]
  4. Pareyson D, Marchesi C. Diagnosis, natural history, and management of Charcot-Marie-Tooth disease. Lancet Neurol. 2009;8:654–667. doi:10.1016/S1474-4422(09)70110-3 [CrossRef]
  5. Rosenbaum AJ, Lisella J, Patel N, et al. The cavus foot. Med Clin North Am. 2014;98:301–312. doi:10.1016/j.mcna.2013.10.008 [CrossRef]
  6. Ward CM, Dolan LA, Bennett DL, et al. Long-term results of reconstruction for treatment of a flexible cavovarus foot in Charcot-Marie-Tooth disease. J Bone Joint Surg. 2008;90:2631–2642. doi:10.2106/JBJS.G.01356 [CrossRef]
  7. Amene C, Levy M, Crawford J. Tumors of the Central Nervous System. New York, NY: Springer; 2014:197–212. doi:10.1007/978-94-007-7037-9_18 [CrossRef]

Differential Diagnosis of Cavus Foot Deformity

Congenital

Clubfoot

Peripheral nervous system

Charcot-Marie-Tooth disease

Peripheral neuropathy

Guillain-Barre syndrome

Central nervous system

Cerebral palsy

Spinal cord tumor

Stroke

Amyotrophic lateral sclerosis

Poliomyelitis

Huntington's chorea

Friedreich's ataxia

Traumatic brain injury

Spina bifida

Syringomyelia

Filum terminale lipoma

Tethered cord syndrome

Traumatic

Compartment syndrome

Crush injury

Postburn contracture

Talar neck fracture malunion

Peroneal nerve injury

No underlying cause

Idiopathic cavus foot

Authors

Ananth S. Eleswarapu, MD, is a Resident, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center. Bakhtiar Yamini, MD, is an Associate Professor of Surgery, Department of Surgery, Section of Neurosurgery, The University of Chicago Medical Center; and an Attending Neurosurgeon, The University of Chicago Hospitals. Robert J. Bielski, MD, is an Associate Professor, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center; and an Attending Pediatric Orthopedic Surgeon, The University of Chicago Medicine Comer Children's Hospital.

Address correspondence to Ananth S. Eleswarapu, MD, Department of Orthopedic Surgery, The University of Chicago Medical Center, 5841 South Maryland Avenue, MC 3079, Chicago, IL 60637; email: ananth.eleswarapu@uchospitals.edu.

Disclosure: The authors have no relevant financial relationships to disclose.

10.3928/00904481-20160426-01

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