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