Foot deformities

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.

Diagnostics

• Complete evaluation of feet, knees, hips, 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 manipulation 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:^[6]

• 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: 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 ^[1]
  • 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
• Treatment
  • Manipulative treatment: the Ponseti-method (manual correction with serial casting )
  • Achilles tenotomy: the equinus foot position may be corrected surgically by lengthening the Achilles tendon with a Z-shaped suture
  • Foot abduction brace (or Ponseti brace)
    • A foot brace consisting of a connecting bar between two footplates, which are adjustable and onto which shoes are attached.
    • Used to treat and prevent relapses in cases of idiopathic clubfoot deformity which have been completely corrected by manipulation, serial casting, and heel cord tenotomy.
• Complications: pathological strain with ulceration and early onset of arthrosis

• 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
• 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
  • Orthotics that support the ball of the foot and provide plantar support to the metatarsal heads
  • Training of the foot muscles
• Complication: Morton metatarsalgia (Morton neuroma) ^[7]
  • Sudden, shooting pain on the plantar side of the foot (between the 3^rd and 4^thmetatarsal)
    • Affected areas are innervated by the common plantar digital nerves (of the medial and lateral plantar nerves of the tibial nerve)
  • Typical signs
    • Mulder 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 sign

Flat feet can be either congenital or acquired.

Congenital flat feet ^[8][9]

• Definition: rare, complex foot deformity with a fixed vertical position of the talus and luxation of the talocalcaneonavicular joint
• Etiology: congenital
  • Concurrent with neurological disorders (particularly meningomyelocele) and systemic diseases
  • Isolated
• 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 a low leg cast (∼ 2 years) is required after surgery to prevent the talus from returning to the vertical position.

Acquired flat feet ^[8]

• 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

• Definition: flexion contracture of the foot
• Etiology: acquired
  • The most common contracture found in patients with cerebral palsy
  • As part of clubfoot deformity
• Pathogenesis
  • In cerebral palsy
    • Spasticity of the sural muscles
    • Spastic contraction of the muscles impairs longitudinal bone growth
  • In clubfoot deformity: See “Pathogenesis” of clubfoot above.
• 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 dorsiflexion → contracture of the gastrocnemius and soleus muscles
      2. Improvement of dorsiflexion → contracture 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
      • Intramuscular lengthening of the gastrocnemius muscle (Baumann procedure)
      • Lengthening of the Achilles tendon
      • Proximalization of the distal insertion of the gastrocnemius muscle on the Achilles tendon

• Definition: distinctly high longitudinal arch, often with varus position of the hindfoot
• Etiology: Congenital or acquired
  • Acquired associated with neurological conditions, muscular imbalance, Charcot-Marie-Tooth disease
  • Can also be 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 and pressure callus under the first and fifth metatarsal heads
• Diagnostics
  • Physical examination: See “Flexible vs. resistant foot deformities.”
  • Neurological evaluation to identify underlying neurological conditions
  • X-ray: foot and upper ankle joint in two planes, including during plantar flexion
• 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

• 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:^[2]

• 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
  • Inferior calcaneal spur: affects the insertion of the plantar fascia, on the inferior aspect of the calcaneus bone (most common form)
  • Posterior calcaneal spur (Haglund exostosis): affects the insertion of the Achilles tendon, on the posterior aspect of the calcaneus bone
• 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.
      • Recommended: single, low-doses of 0.5 Gy (maximum dose of 3–12 Gy)
    • Surgical removal of the spur

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