Pes planus/cavus

Author(s): David Berbrayer, MD

Originally published:09/15/2015

Last updated:09/15/2015

1. DISEASE/DISORDER

Definition

Pes planus, also know as “flat foot” may be acquired or congenital. With Pes Planus, the patient initially complains of pain and swelling in the medial ankle and midfoot during weight bearing. Loss of push-off strength during gait occurs, and the patient may develop a limp. As the patient’s heel displaces into valgus and the forefoot abducts, pressure between the calcaneus and fibula may develop, causing painful impingement between the lateral ankle and calcaneus. Abnormal wear of the medial heel and inner border of shoe wear may also be noted. Contraction of the posterior tibial tendon causes inversion of the midfoot and elevation of the medial longitudinal arch through its broad insertion on the navicular, cuneiforms, medial 3 metatarsal bases, and cuboid. Loss of posterior tibial function due to stretching or rupture of the tendon removes the primary inverter of the foot and leaves the primary and secondary everters of the foot, the peroneus brevis and longus, relatively unopposed. Therefore, posterior tibial dysfunction leads to flattening of the medial longitudinal arch, forefoot abduction, and hindfoot valgus.10-19

Pes cavus is a high arch of the foot that does not flatten with weight bearing. The deformity can be located in the forefoot, the midfoot, the hindfoot, or a combination of these sites. 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. (2)

Etiology

Acquired pes planus may be caused by dysfunction of the posterior tibial tendon (PTT) and also involves the spring-ligament complex, the talocalcaneal interosseous ligament and the deltoid ligament or loss of the medical longitudinal arch. Younger patients who present with rigid flatfoot should be screened for tarsal coalition, congenital vertical talus, or other forms of congenital hindfoot pathology (10-15)

80% pes cavus is caused by malunion of calcaneal or talar fractures, burns, sequalae resulting from compartment syndrome, residual clubfoot or neuromuscular disease (e.g. muscular dystrophy, Charcot-Marie-Tooth (CMT) disease, spinal dysraphism, polyneuritis, intraspinal tumors, poliomyelitis, syringomyelia, Friedreich ataxia, cerebral palsy, and spinal cord tumors). (2,3,6)

Epidemiology and Risk factors for Prevention

Clinical entities that have been found to contribute to the development of PTT dysfunction include diabetes mellitus, hypertension, steroid exposure, or previous trauma or surgery in the medial foot region. (10-19)

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

  1. Malunion of calcaneal or talar fractures
  2. Burns
  3. Sequelae resulting from compartment syndrome
  4. Residual clubfoot
  5. 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, 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. Duchenne described intrinsic muscle imbalances causing an elevated arch.(3-9)

Ferciot estimated a 5% incidence of flatfoot in all children and adults.(18) Harris and Beath studied 3,619 Royal Canadian Army recruits and found that 15% had a simple hypermobile flatfoot, 6% had simple hypermobile flatfoot with a tight heel cord, and 2% had a tarsal coalition. (19)

Significant History

Patho-anatomy and Physiology:

Arthritides, both inflammatory and degenerative, must also be examined as a possible underlying cause of pes planus. Degenerative arthritides typically have signs and symptoms in and around the midfoot region with accompanying pain and exostosis. Fracture-dislocation that involves the medial column (navicular and first metatarsal), Lisfranc joints, and calcaneal fractures have been noted to cause pes planus, usually because of malunion or chronic joint subluxation. Ruptures of either the spring ligament or the plantar fascia (traumatic and iatrogenic) have been reported to lead to progressive collapse of the medial longitudinal arch. Midfoot collapse secondary to Charcot neuroarthropathy with a resultant rockerbottom foot may necessitate a completely different route of intervention and treatment from those that are used for patients with Pes Planus. Ruptures of the PTT tendon occur especially around the medial malleolus. This region corresponds to a relatively avascular area of the PTT, between the navicular bone and the medial malleolus. Non-traumatic tears usually occur in this hypovascular location, suggesting a possible etiology of ischemia and subsequent tendinosis. Pes cavus caused by Charcot Marie Toothe disease occurs because antagonist muscles, the posterior tibialis and peroneus longus, pull harder than the other muscles, resulting in deformity. Specifically, the peroneus longus pulls harder than the weak anterior tibialis, causing plantarflexion 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.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time):

  1. New onset, acute. Initial onset of pes planus may be asymptomatic aside from cosmetic appearance of pronation. Initial stage 1 findings include mild tenderness along the inframalleolar course of the PTT, with minimal (if any) loss in tendon strength as assessed by the single-limb heel-rise test. Pes cavus presents with pain on lateral weight bearing. 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.
  2. In pes planus, pain is felt medially in midfoot and hindfoot around the medial malleolus and navicular. In sub-acute disease, there is a dynamic deformity, typically hindfoot valgus with forefoot abduction.

Palpation along the course of the PTT demonstrates pain and possibly hypertrophy or defects. Observing the patient’s stance from behind reveals increased visualization of the lateral toes (too-many-toes sign) on the affected extremity secondary to weakness.

In pes cavus, metatarsalgia with painful callus over 2nd and 3rd metatatarsals is present as well as lateral foot pain.

  1. Chronic/stable. Patients with pes planus are unable to lock the transverse tarsal joints, thus preventing the formation of a rigid lever arm and transforming the foot into a “bag of bones.” Clinical manifestations that ensue include the inability to perform a single-leg heel rise. This inability to invert the heel results in chronic heel valgus and subsequent Achilles contracture. Excessive forefoot abduction further stresses the static stabilizers of the midfoot. As the static and dynamic stabilizers of the arch are overloaded, more foot pain occurs. In order to achieve a plantigrade foot in the setting of a fixed hindfoot valgus, the forefoot typically compensates into a fixed supination position. Patients often present with lateral pain secondary to subfibular impingement as the calcaneus subluxes and the flatfoot deformity progresses. Long-standing hindfoot valgus places increasing stress on the deltoid complex, with eventual loss of competence. The resultant valgus tilt of the talus leads to eccentric loading of the ankle with subsequent tibiotalar arthrosis. In pes cavus, 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. Cock-up toes can be observed with recruitment of the extensor hallucis longus (EHL). The shoe should also be inspected for increased lateral wear. The forefoot is observed for plantarflexion, and the hindfoot is observed for varus.
  2. Pre-terminal. In pes planus, chronic painful callus (tyloma) develops medially and over the lateral heel and medial aspect of first ray. In pes cavus, chronic painful callus (tyloma) develops over metatarsals especially 2nd and 3rd head and over medial aspect of heel.

Specific secondary or associated conditions and complications:

Untreated, both conditions lead to abnormalities in gait, painful callus, progressive toe deformities, difficulty finding comfortable shoes, and degenerative changes in the foot. If left untreated, both conditions will affect the kinetic chain resulting in an antalgic gait and pain involving the ipsilateral knee, hip and low back pain.

2. ESSENTIALS OF ASSESSMENT

History

Pes planus may present with pain and an abducted forefoot and valgus hindfoot. Pes cavus presents with forefoot plantarflexion and hindfoot varus.

Physical Examination

The most frequently affected dynamic stabilizer in pes planus is the posterior tibial tendon (PTT), and it is the most powerful invertor of the foot and serves as an important dynamic arch stabilizer. Originating from the posterior aspect of the tibia, intraosseous membrane, and fibula, the posterior tibial muscle and tendon pass posteromedially behind the medial malleolus and then insert via multiple bands into the navicular, cuneiforms, metatarsal bases (second through fourth), and the sustentaculum tali. Ankle plantarflexion and forefoot adduction-supination with resultant subtalar inversion are key functions of the PTT because of its posteromedial position. Important clinical signs of PTT dysfunction, the too-many-toes sign and the single-limb, heel-rise test, were discussed by Johnson in 1983.21

In pes cavus, 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. Cock-up toes can be observed with recruitment of the extensor hallucis longus (EHL). A neurologic examination is required, specifically including detailed muscle strength testing.

Functional Assessment

The gait cycle assists in differentiating the two conditions. In pes planus, the foot must transition from a flexible construct at heel strike (to accommodate irregular surfaces) to a rigid construct at pushoff (to maintain a rigid lever for ambulation. At heel rise, PTT initiation of transverse tarsal joint adduction with resultant subtalar inversion causes the talonavicular and calcaneocuboid joint axes to be perpendicular and therefore locked. This process converts the foot into a rigid lever arm against which the powerful gastrocsoleus complex acts to propel the body forward. In pes cavus, the range of motion of the ankle, subtalar, midfoot, and forefoot is examined. The deformity is determined to be flexible or rigid. Motor strength and sensory testing is important.

Laboratory Studies

In Pes Planus, a painless, atraumatic flatfoot deformity in an insensate foot is most likely due to neuroarthropathy (Charcot foot). The most common cause of neuroarthropathy in the United States is diabetes. If diabetes mellitus is not already diagnosed, a fasting blood glucose test is indicated.

If the patient has pain in multiple joints, consider a workup for rheumatoid arthritis or seronegative spondyloarthropathy with rheumatoid factor, erythrocyte sedimentation rate, and HLA-B27

Imaging

In Pes Planus, protocol includes three weightbearing views for the foot (anteroposterior [AP], oblique, and lateral) and three weightbearing views for the ankle (AP, mortise, and lateral).

Evaluation of longitudinal arch collapse is largely dependent upon weight-bearing lateral radiographs. The axis of the talar-first metatarsal angle on the lateral weight-bearing foot radiograph is the most discriminating radiographic parameter in patients with symptomatic flatfoot. Alternatively, the distance between the medial cuneiform and the floor is a strong reflection of medial arch collapse and flatfoot. Additional features of flatfoot deformity that are noted on the lateral view include talar plantar flexion and decreased calcaneal pitch.

An AP standing foot projection is primarily used for evaluating talar head uncoverage secondary to lateral deviation of the navicular. As peritalar lateral subluxation increases, the talonavicular coverage angle—created by two reference lines through the centers of the talar head and navicular bone, respectively—reveals increased angles. Alternatively, using the talonavicular incongruency angle to measure forefoot abduction results in improved interrater reliability.

Standing AP radiographs of the ankle are evaluated for evidence of valgus talar tilt with resultant subluxation, arthrosis, or both. The ankle view is particularly important in patients who have fixed hindfoot valgus

In Pes Cavus, standing x-rays of ankle and foot AP (Lateral and oblique) should be inspected for evidence of degenerative arthritis, as well as for 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. Magnetic resonance imaging (MRI) of the spine should be performed if unilateral progressive cavus is present in a patient without a history of trauma.

If warranted, Additional studies include: CT, MRI, bone scan, gait analysis and ultrasound to assess tendon function.

MRI is helpful in diagnosing posterior tibial tendon dysfunction, but it is not required to make the diagnosis. Although it is sensitive, MRI can cause overestimation of the degree of tendon degeneration based on surgical findings, with a mere 40% correlation between MRI and surgical findings. This MRI classification is useful in predicting the outcome of tendon transfer, with higher grades of tendon degeneration faring worse than mild grades of degeneration.

Supplemental assessment tools

The Coleman block test determines if the subtalar joint is flexible. 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. If the hindfoot does not correct, the deformity is rigid.

With pes cavus and associated Charcot Marie Toothe Disease, EMG and nerve conduction study and genetic studies may help classify sub-group.

Early predictions of outcomes

Reduction of pain and improved gait is best predictor of outcome.

Johnson and Strom described 4 stages of posterior tibial tendon dysfunction.22 These stages are used to dictate treatment.

Stage 1 is characterized by peritendinitis and tendon degeneration, but the tendon length remains normal. This stage presents clinically as pain and swelling along the posterior tibial tendon sheath.

In Stage 2, the posterior tibial tendon elongates, and a supple flat foot deformity develops. Although deformed on weight bearing, the hindfoot and midfoot deformities are passively correctable to neutral.

Stage 3 occurs over time as the hindfoot becomes rigid in a valgus position, and the patient develops a rigid flatfoot deformity.

Stage 4 develops as the deltoid ligament becomes incompetent and the talus tilts into valgus within the ankle mortise.

Environmental

A hard floor surface with safety shoes will increase pain in both conditions. Uneven ground without proper foot wear will increase pain in both conditions.

Social role and social support system

In both conditions, the employer must be willing to make accommodations to decrease pain. This may involve shoe modifications, NSAIDS or orthotics. The family should be supportive to allow eventual return to function.

Professional Issues

Depending on the site of employment, an employee may be required to continue to wear safety shoes. In those circumstances modifications may be required to allow continued employment.

3. REHABILITATION MANAGEMENT AND TREATMENTS

Available or current treatment guidelines

For pes planus, there are established clinical guidelines for diagnosis and treatment. The guidelines assist in establishing the diagnosis and rendering treatment.(1)

There are patient education guidelines for treatment of pes cavus established by the United Kingdom (Royal National Orthopedic Hospital) (24)

At different disease stages

new onset/acute includes
Initial treatment of pes planus consists of activity modifications, weight loss, orthotic management (foot orthosis or ankle foot orthosis), NSAID (topical or oral), physical therapy and shoe modifications. Patient education is considered if asymptomatic. For varus deformities, a lateral wedge sole modification can improve function.

The following is a summary of conservative treatments for acquired flatfoot( Pes Planus):

Stage 1 – NSAIDs and short-leg walking cast or walker boot for 6-8 weeks; full-length semirigid custom molded orthosis, physical therapy

Stage 2 – UCBL orthosis or short articulated ankle orthosis

Steroid injection into the posterior tibial tendon sheath is not recommended due to the possibility of causing a tendon rupture.

In pes cavus, the goal of treatment is to allow the patient to ambulate without symptoms. Non-operative 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 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.

Sub-acute care
With Pes Panus, consider molded AFO, double-upright brace, or patellar tendon–bearing brace should be considered.

Patient education would involve activity modification and stretching of gastrosoleus and plantar fascia. Patients need to be informed about foot protection – with sensory changes with the use of extradepth orthopedic footwear and early treatment of any cuts or callus.

With Pes Cavus, consider AFO (Ankle Foot Orthosis with plastazote linings) and frequent inspection of the skin for potential ulceration. The use of the AFO depends on the degree of weakness of the ankle and foot. If weakness is not present then a lateral wedge on the sole with foot orthotics may be sufficient. (3-9)

chronic/stable care includes:
With pes planus, consider molded AFO, double-upright brace, or patellar tendon–bearing brace. Orthotic management is successful in older low-demand patients and surgical treatment can be reserved for those patients who fail non-operative treatment.

Orthopedic referral with surgical consideration when appropriate may include: Osteotomy, arthrodesis, fusion, tendon transfers, plantar fascia release, and great toe Jones procedure are often considered. An absolute contraindication for surgery is poor vascularity. Revascularization should be performed before reconstruction. 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. Outcomes of surgery may not totally eliminate pain but may improve function. The goal of surgery is to produce a pain-free plantigrade balanced foot.

In pes cavus, surgical decision-making requires a careful and complete examination of the foot and ankle, especially for rigidity, strength, and deformities. The goal of surgery is to provide a plantigrade foot.

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. A great toe Jones procedure is performed for a cock-up deformity of the great toe with associated weakness of the anterior tibialis. 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 Girdlestone-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. 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 disease. Tarsal osteotomy has been described for deformities through the midfoot; however, these osteotomies require cutting through multiple joints. 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. 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, a tendon transfer. 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.(3-9)

Pre-terminal or end of life care
N/A

Coordination of care

Parallel practice: Patients may be rehabilitating but still working or competing.
Coordinated: Employers, coaches and family may need to be involved to promote a successful outcome
Multidisciplinary: Athletic trainers, physical therapists, orthotists may be involved.
Interdisciplinary: Foot-ankle trained orthopedic surgeons or podiatrists can be consulted in refractory cases
Integrated: n/a

Patient & family education

Educate on the importance of foot and ankle stretching, appropriate training volume and intensity, appropriate shoe (and orthotic) wear. Different athletic shoes should be worn every 6 months and can be rotated for longer wear.

Emerging/unique Interventions

Impairment-based measurement
Occasionally, pes planus and pes cavus can lead to work time loss if the injured worker has a job that requires running or long-distance walking. In sports, careful return to activity needs to be monitored by the team physician and this requires patient education.

Measurement of patient outcomes

The Foot Function Index (FFI) is a 0-10 scale of pain and foot function over time in standing, walking, etc. The Foot Health Status Questionnaire (FHSQ) is a 42-item questionnaire assessing quality of foot health. The Foot and Ankle Ability Measure (FAAM) is an activities-of-daily-living scale of foot health.) These measures can be used to assess pain severity and to monitor response to treatment.

4. GAPS IN THE EVIDENCE-BASED KNOWLEDGE

New techniques of pain management include different types of foot orthotics and ankle bracing. The role of PRP, prolotherapy, botulinum toxin, percutaneous needle tenotomy, stem cells need to be evaluated. Considerable controversy remains about the appropriate treatment of all stages of PTT dysfunction. Comparison-outcome trials are needed to provide better data to evaluate the treatment options. The current controversy in the reconstruction of these deformities is whether to proceed with osteotomies and tendon transfers or arthrodesis.

5. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE

New treatment techniques include extracorporeal shockwave therapy (ESWT), ultrasound guided corticosteroid injection, percutaneous needle tenotomy, platelet rich plasma (PRP), prolotherapy, and potentially in the future, stem cell therapies to promote healing.

Newer materials for orthotics and knowledge of different shoes for different activities are important. Minimal invasive surgical techniques are emerging.

REFERENCES

  1. Clinical Practice Guideline Adult Flatfoot Panel: Michael S. Lee, DPM,John V. Vanore, DPM,James L. Thomas, DPM,Alan R. Catanzariti, DPM,Geza Kogler, PhD, Steven R. Kravitz, DPM,6 Stephen J. Miller, DPM,andSusan Couture Gassen Diagnosis and Treatment of Adult Flatfoot The Journal of Foot and Ankle Surgery VOLUME 44, NUMBER 2:79-113 MARCH/APRIL 2005
  2. Wapner KL, Myerson MS. Pes cavus. In: Myerson MS, ed. Foot and Ankle Disorders. Philadelphia, Pa: WB Saunders; 2000:919-941

Other Resources

Wapner KL, Myerson MS. Pes cavus. In: Myerson MS, ed. Foot and Ankle Disorders. Philadelphia, Pa: WB Saunders; 2000:919-941.

Gallardo E, García A, Combarros O, Berciano J. Charcot-Marie-Tooth disease type 1A duplication: spectrum of clinical and magnetic resonance imaging features in leg and foot muscles. Brain. Feb 2006;129(Pt 2):426-37. [Medline].

Berciano J, Gallardo E, García A, Pelayo-Negro AL, Infante J, Combarros O. New insights into the pathophysiology of pes cavus in Charcot-Marie-Tooth disease type 1A duplication. J Neurol. Sep 2011;258(9):1594-602. [Medline].

Burns J, Crosbie J, Hunt A, Ouvrier R. The effect of pes cavus on foot pain and plantar pressure. Clin Biomech (Bristol, Avon). Nov 2005;20(9):877-82. [Medline]

Author Disclosure

David Berbrayer, MD
Nothing to Disclose

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