• Clinical science

Foot deformities

Abstract

Foot deformities are a heterogeneous group of congenital and acquired conditions involving structural abnormalities or muscular imbalances that affect the function of the foot. The deformities are classified according to clinical appearance. The most recognizable congenital foot deformity is the clubfoot deformity, which is characterized by plantar flexion of the ankle, inversion of the foot, and adduction of the forefoot. Manipulative treatment of congenital foot deformities, which requires manual repositioning and serial casting, should be initiated immediately after birth. The outcome depends primarily on whether the deformity responds well to manual repositioning (flexible deformities). Resistant deformities often require surgical correction.

Overview

Foot deformity Etiology Characteristics Therapy
Club foot
  • Congenital (common) or acquired (rare)
  • Differential diagnosis: postural clubfoot
  • Bilateral in 30–50% of cases
  • Mechanism
  • Deformity: foot points downwards and inwards
    • Hindfoot equinus and varus
    • Midfoot cavus
    • Forefoot varus
    • Limited dorsiflexion and subsequent plantar flexion of ankle
  • Diagnosis
    • Clinical diagnosis (prenatal detection via ultrasound possible)
    • X-ray (can confirm clinical diagnosis): long axis of talus and calcaneus are parallel
  • Manual repositioning and serial casting immediately after birth
  • If manual repositioning is unsuccessful: surgical release of contractures and correction of bone alignment

Equinus deformity

  • Congenital
  • Acquired
  • Toe walking
  • Unilateral equinus → leg length discrepancy
  • bilateral equinus → impaired stability
  • Attempt manipulative therapy
  • Surgical correction
Pes cavus
  • Congenital or acquired
  • High longitudinal arch
  • Hindfoot varus
  • Physiotherapy, orthotics
  • If conservative measures are unsuccessful: surgical correction
Metatarsus adductus
  • Most common cause of in-toeing in children < 1 year of age (the most common cause of in-toeing in children up to the age of 3 years is tibial torsion and > 3 years is femoral torsion)
  • Idiopathic but associated with hip dysplasia
  • Differential diagnosis of in-toeing: internal tibial torsion, femoral antetorsion
  • In-toeing
  • The deformity may be flexible or rigid
  • X-ray: increased angle between the 1st and 2nd metatarsal bones
  • Rarely requires treatment and resolves spontaneously in > 95% of cases within the first 18 months of life
  • For severe cases (rigid deformity, passive correction impossible): casting

Congenital flat foot

  • Congenital
  • Convex plantar surface
  • X-ray: vertical position of the talus
  • Manipulative treatment immediately after birth
  • Surgery is usually required.
Acquired flat foot
  • Acquired
  • Flat or convex flat surface
  • Orthotics
  • Surgery
Splay foot
  • Acquired
  • Shoe inserts that support the ball of the foot
Calcaneal spur
  • Idiopathic
  • Risk factors: abnormal strain, obesity, foot deformities

References:[1][2][3][4][5][6][7][8][9]

Diagnosis and treatment of foot deformities

Diagnosis

  • Complete evaluation of feet, knee joints, hip joints, and spine
  • Flexible vs. resistant foot deformities
    • Evaluation of foot deformities, according to whether the deformity may be corrected with active (muscular contraction) or passive (manual correction by examining physician) manipulation.
      • Resistant deformity: difficult or impossible to correct → indicates a structural abnormality
      • Flexible deformity: may be easily corrected → indicates a muscular imbalance
  • X-ray: evaluate skeletal deformities

Basic principles of treatment

  • Correctable foot deformities: foot orthotics and manipulative treatment with casting and splinting are usually successful
  • Resistant foot deformities: surgical correction is usually required to reposition structures or relieve muscle contractures

Prompt treatment of congenital foot deformities is vital! Surgery may often be avoided if the manipulative treatment is implemented correctly and consistently! If muscular imbalances are not corrected at an early age, they may result in structural deformities and often require surgery!

References:[10]

Clubfoot (talipes equinovarus)

  • Definition: Clubfoot is a complex foot deformity that is comprised of five fixed deformities.
    • Hindfoot
      • Equinus foot position: short Achilles tendon fixes the foot in plantar flexion
      • Varus position = supination of the calcaneus
    • Forefoot
      • Adductus; (Pigeon toe, false clubfoot, metatarsus adductus): medial deviation of the toes (adduction of the forefoot)
      • Supinatus: inversion of the forefoot
    • Cavus (high arch): distinct arching of the foot
  • Epidemiology
    • One of the most common congenital anomalies (∼ 1/1000 births)
    • Bilateral involvement in ∼ 50% of cases
  • Etiology
    • Congenital: most common form
    • Acquired: rare (e.g., secondary to neurological conditions or trauma)
  • Pathogenesis
    • Dominant medial musculature; posterior tibial muscle is considered to be the muscle primarily responsible for the clubfoot (→ plantar flexion and supination, particularly of the hindfoot)
    • Medial deviation of the talar neck
    • Weak peroneus muscles
    • Shortened Achilles tendon
  • Diagnostics
    • Physical examination: See “Diagnosis and treatment of foot deformities” above.
    • X-ray: The long axes of the calcaneus and talus are parallel.
  • Differential diagnosis: postural clubfoot
  • Complications: pathological strain with ulceration and early onset of arthrosis
  • Treatment
    • Manipulative treatment: the Ponseti-method (manual correction with serial casting ) should be initiated within 24 hours of birth
    • The equinus foot position may be corrected by surgically lengthening the Achilles tendon with a Z-shaped suture

Manipulative treatment should begin within 24 hours of birth!

References:[1][6]

Splayfoot (pes planotransversus, pes transversoplanus)

  • Definition: spreading apart of the metatarsal bones with subsequent lowering of the metatarsal heads
  • Epidemiology: most common foot deformity
  • Etiology: muscular and connective tissue weakness (worsened by unsupportive footwear)
  • Clinical features
    • Metatarsalgia: pain in the metatarsal bone joints II–IV → abnormal strain on the metatarsal heads II–IV → painful callus .
    • Hallux valgus; and digitus quintus varus: malalignment of the first and fifth ray
  • Complication: Morton's metatarsalgia (Morton's neuroma)
    • Sudden, shooting pain on the plantar side of the foot (between the 3rd and 4th metatarsal)
    • Affected areas are innervated by the common plantar digital nerves (of the medial and lateral plantar nerves of the tibial nerve)
    • Typical signs
      • Mulder's sign
        1. The forefoot is held firmly with one hand in the medial-lateral direction.
        2. Pressure is applied to the sole of the foot between the metatarsal heads (at the location of symptoms).
        3. If pain is perceived (especially on the plantar side), it indicates Morton neuroma.
          • This maneuver may also produce a “click” or snapping sensation, which is known as Mulder's click.
      • Tinel's sign
  • Diagnostics
    • Physical examination: See “Diagnosis and treatment of foot deformities” above.
    • X-ray
      • Spreading apart of the metatarsal heads
      • Erosion of the second to fourth metatarsal heads
      • Malalignment of the first and fifth ray
  • Treatment: shoe inserts that support the ball of the foot and provide plantar support to the metatarsal heads; training of the foot muscles

References:[11][7]

Congenital flat feet (talus verticalis, pes planus congenitus)

  • Definition: rare, complex foot deformity with a fixed vertical position of the talus and luxation of the talocalcaneonavicular joint
  • Etiology
    • Congenital
      • Isolated
      • Concurrent with neurological disorders (particularly meningomyelocele) and systemic diseases
  • Pathogenesis
    • Cranial luxation of the navicular bone
    • (Sub)luxation of the talonavicular joint and the subtalar joint
    • Short Achilles tendon
  • Clinical features
    • Abduction, pronation, and dorsal extension of the forefoot
    • Convex plantar surface
  • Diagnostics
    • Physical examination: palpation of the head of the talus
    • X-ray: axes of tibia and talus appear parallel on the lateral image
  • Treatment
    • Similar measures as those applied in the treatment of clubfoot: begin corrective casting immediately after birth
    • Purely conservative treatment is rarely successful → surgical correction within the first 3 years of life
      • Posterior capsulotomy of the upper and lower ankle joint + lengthening of the Achilles tendon + open repositioning of the talocalcaneonavicular joint
    • Long-term treatment with low leg cast (∼ 2 years) is required after surgery to prevent the talus from returning to the vertical position.

References:[12][13]

Adult-acquired flat foot deformity (pes planus)

  • Definition: acquired flexible deformity of the foot with complete lowering of the longitudinal arch (posterior tibialis tendon insufficiency). The plantar surface of the foot is flat or convex.
  • Etiology
    • End-stage of planovalgus foot
    • Posttraumatic
  • Treatment
    • Orthotics or ankle braces that support the longitudinal arch (supination wedge) → to straighten the heel
    • Surgery should be performed (osteotomy, arthrodesis) if conservative treatment is unsuccessful

References:[12]

Equinus deformity (pes equinus)

  • Definition: flexion contracture of the foot
  • Etiology: acquired
  • Pathogenesis
  • Clinical features
    • Toe walking: an abnormal gait, characterized by impaired dorsiflexion ; the toes point downward, while the heels do not have contact to the ground.
    • Gait instability
    • Unilateral equinus:
      • Leg length discrepancy: functional elongation of the affected limb while walking → outward swing of the leg → pelvic asymmetry and back pain
    • Bilateral equinus:
      • Impaired stability with increased risk of falling; no leg length discrepancy
  • Diagnostics
    • See “Diagnosis and treatment of foot deformities” above.
    • Silfverskjöld test
      • Method
        1. Evaluate active and passive dorsiflexion in the upper ankle joint, while the knee is fully extended
        2. Repeat evaluation while the knee is in 90° flexion position
      • Findings/interpretation
        1. No improvement of dorsiflexioncontracture of the gastrocnemius and soleus muscles
        2. Improvement of dorsiflexioncontracture of the gastrocnemius muscle
  • Treatment
    • Equinus associated with the clubfoot deformity
      • Usually requires surgical treatment: elongation of the short Achilles tendon
    • Equinus secondary to cerebral palsy
      • Conservative methods: flexible equinus
        • Casting of the lower limb in dorsiflexion to stretch the sural muscles. This method may be combined with botulinum toxin administration
        • Botulinum toxin: injection in the sural muscles leads to relaxation for approx. 3–6 months
        • Ankle-foot orthosis
        • Physiotherapy: stretching of the sural muscles
      • Surgical methods: resistant equinus or insufficient response to conservative methods

Pes cavus (carvovarus foot, talipes cavus, high instep, high arch)

  • Definition: distinctly high longitudinal arch, often with varus position of the hindfoot
  • Etiology:
    • Acquired; associated with neurological conditions
    • Idiopathic (often bilateral)
  • Pathogenesis
    • Develops during periods of bone growth
    • Contracture of the plantar fascia and digital extensors
    • Imbalance between weak dorsiflexion (primarily anterior tibial muscle) and dominant plantar flexion (peroneal muscles)
  • Clinical features local pain und pressure callus under the first and fifth metatarsal heads
  • Diagnostics
  • Treatment
    • Conservative: flexible cavovarus foot
      • Physiotherapy, shoe inserts, and orthotics
    • Surgical: resistant pes cavus or unsuccessful conservative treatment
      • Plantar fascia release
      • Tendon transfer
      • Osteotomy: various methods
      • In severe cases: triple arthrodesis

Metatarsus adductus, curved foot (metatarsus varus)

  • Definition: adduction of the forefoot
  • Etiology: unclear; presents immediately at birth
    • Increased risk in cases of intrauterine malposition
    • Association with hip dysplasia
  • Pathogenesis: a muscular imbalance between the adduction muscles and fibularis muscles is suspected to be the underlying cause
  • Clinical features
    • In-toeing of forefoot
    • Usually painless
    • Cases with high angles of adduction deformity (i.e., increased curvature of the forefoot, increased amount of in-toeing) may present with a medial skin crease over the forefoot
  • Diagnostics
    • Physical examination: See flexible vs. rigid foot deformities above.
    • Gentle palpation of the lateral aspect of the foot → active correction of the deformity → indicates a mild correctable foot deformity
  • Differential diagnoses
    • Tibial torsion
    • Femoral anteversion
  • Treatment
    • Flexible curved feet do not usually require treatment.
    • Rigid curved feet or flexible curved feet that do not reposition spontaneously require conservative treatment.
      • Splintage and casting to correct the position of the foot
      • Orthotics and inserts
    • Surgery is required in cases that do not respond sufficiently to conservative treatment.
      • Reduction osteotomy of the cuboid bone (lateral ray is shortened) or wedge-insertion osteotomy of the cuneiform bone (medial ray is lengthened)

References:[3][7]

Calcaneal spur (heel spur)

  • Definition: ossification of tendon insertions at the calcaneus bone
  • Etiology: abnormal strain, obesity, foot deformities
  • Pathogenesis: idiopathic; repetitive microtrauma of the tendon insertion has been suggested as an underlying cause
  • Clinical features: localized pain
  • Forms
  • Treatment
    • First-line treatment is conservative
      • NSAIDs
      • Cryotherapy in cases with acute painful inflammation; otherwise thermal therapy (therapeutic ultrasound)
      • Immobilization, sports restriction, orthotics, avoidance of tight, uncomfortable footwear
    • Alternative treatment
      • Radiotherapy: a standardized treatment scheme does not exist. Single, low-doses of 0.5 Gy (maximum dose of 3–12 Gy) are recommended
      • Surgical removal of the spur