Updated: 6/14/2021

Equinovarus Foot

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  • summary
    • Equinovarus Foot is an acquired foot deformity commonly seen in pediatric patients with cerebral palsy, spina bifida, and Duchenne Muscular Dystrophy that present with a equinovarus foot deformity. 
    • Diagnosis is made clinically with presence of an inverted heel with a supinated forefoot, often associated with pain and callous formation along the lateral border of the foot.
    • Treatment ranges from bracing to tendon transfers to osteotomies depending on the underlying etiology, severity of deformity, and rigidity of contracture.
  • Epidemiology
    • Incidence
      • common foot deformity seen with
        • cerebral palsy (usually spastic hemiplegia)
        • Duchenne muscular dystrophy
        • residual clubfoot deformity
        • spina bifida
        • tibial deficiency (hemimelia)
          • though this condition is very rare
  • Etiology
    • Pathophysiology
      • pathomechanics
        • imabalance of invertors and evertors (invertors overpower the evertors)
        • relative overpull of
          • tibialis posterior and/or
          • tibialis anterior
          • gastoc-soleus complex
        • example: in cerebral palsy
          • the causative muscles for the varus are the
            • anterior tibialis (AT) in 1/3 of patients
            • posterior tibialis (PT) in 1/3 and
            • both the AT and PT in the remaining 1/3
      • foot deformity muscle imbalance overview
  • Presentation
    • Symptoms
      • pain
        • painful weight bearing over the lateral border of the foot
      • instability
        • during stance phase
        • results in shortened single limb stance
      • poor shoe and/or brace fitting and shoe wear problems
    • Physical Exam
      • inspection
        • inverted heel (tibialis posterior typically implicated)
        • supinated forefoot (tibialis anterior)
        • callous and pain along lateral border
        • intoeing gait (foot progression angle is more internal than knee progression angle)
      • provocative tests
        • active dorsiflexion of foot
          • if foot supinates with dorsiflexion, the anterior tibialis is implicated
        • confusion test
          • indications
            • used in those with poor selective motor control, as in CP, and cannot dorsiflex foot when asked)
          • method
            • patient performs active hip flexion (with or without resistance) while seated
            • results in ankle dorsiflexion due to mass action pattern of leg
            • if the foot supinates with dorsiflexion, the tibialis anterior is likely a contributing to the varus deformity
      • Coleman block test
        • indications
          • to test rigidity of the varus deformity
          • do not do this in children with limited balance such as CP
        • method
          • patient stands on a block with the first ray off the block
          • if the varus corrects, the deformity is flexible
      • manual manipulation of the hindfoot
        • can be used to asses rigidity of the varus deformity
          • passive eversion of the hindfoot past neutral demonstrates that the varus deformity is flexible
  • Imaging
    • Radiographs
      • recommended views
        • AP + lateral of foot
      • findings
        • forefoot adduction is seen on the AP radiograph
        • the talus and calcaneus are more parallel than in typical feet
        • one can often "look down" the sinus tarsi through a visual hole there
        • the calcaneus looks foreshortened on the lateral view
        • the metatarsals are often "stacked" on the lateral view (instead of being in line with one another)
        • stress fractures along the fourth and/or fifth metatarsal bases can develop secondary to repetitive load along the lateral border of the foot.
  • Studies
    • Dynamic EMG
      • may be useful in distinguishing whether tibialis anterior and/or tibialis posterior is/are causing the varus in CP
  • Treatment
    • Nonoperative
      • ankle foot orthosis (AFO)
        • helps provide stability for the foot and a more stable base of support during gait
        • should have a "wrap around" hindfoot component of the brace to help control the varus and minimize pressure points
      • serial casting
        • indication
          • rigid deformity
      • botulinum toxin injection into tibialis posterior and/or gastrocnemius
        • indication
          • flexible or dynamic deformities
          • desire to delay surgery
    • Operative
      • gastrocnemius recession or tendoachilles lengtheing (TAL) for equinus
        • indications
          • fixed equinus unresponsive to non-operative measures
          • gastrocnemius recession should be performed if the anke can be brought to neutral or above neutral with the knee flexed and hindfoot inverted, but not when the knee is extended
          • TAL should be performed if the ankle can not be dorsiflexed to neutral with the knee flexed or extended
      • split-posterior tibialis tendon transfer [SPOTT] or posterior tibial tendon lengthening (PTTL)
        • indications
          • soft tissue balancing is required if varus is flexible or rigid
          • varus foot recalcitrant to non-operative measures and posterior tibialis contributing to varus (dynamic EMG, when available is helpful)
          • tibialis posterior spastic in both stance and swing phase (continous activity)
          • common patient: spastic hemiplegia in ages 5 to 7 years old
        • technique
          • SPOTT
            • reroute half of tendon laterally and insert into peroneus brevis
          • PTTL
            • fractional lengthening of the tendon in the distal third of the lower leg
          • either PTTL or SPOTT may be combined with SPLATT
        • outcomes
          • results for both surgeries are good, without clear indications for transfer versus lengthening
      • split-anterior tibialis tendon transfer [SPLATT]
        • indications
          • overactive anterior tibialis on EMG
          • when anterior tibialis contributes to varus foot, whether flexible or rigid varus deformity
        • technique
          • split anterior tibialis transfer to cuboid, peroneus tertius, or peroneus brevis
          • may be combined with SPOTT or PTTL
      • calcaneal osteotomy
        • indications
          • required for a rigid hindfoot varus deformity
        • technique
          • lateral closing wedge osteotomy (Dwyer) to incur valgus to the heel, OR
          • lateral calcaneal sliding osteotomy to correct the varus
          • typically combined with soft tissue balancing (as above)
  • Complication
    • Overcorrection (resultant valgus deformity)
      • increased risk in
        • children who undergo surgery at younger age
        • children with diplegia (as oppose to hemiplegia)
    • Wound complications
      • most common with calcaneal osteotomy lateral incision
      • risk decreased by using absorbable suture
    • Hardware Pressure sores/ulcers
      • from buttons on bottom of foot (from SPLATT to cuboid)
      • has led some surgeons to always transfer SPLATT to peroneus tertius or brevis
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