Definition
· The most common acquired foot & ankle deformity in adults with upper motor neuron lesions (cerebrovascular accident, traumatic brain and spinal cord injury)
· Upper motor neuron disruption leads to paralysis, muscular imbalance, and spasticity, resulting in progressive deformity
Anatomy
· There are muscular imbalance that cause equinus and varus
· Equinus: gastrocnemius – soleus complex contracture
· Varus: relative overpull of the tibialis anterior muscle
· Secondary contributors: FHL, FDL, intrinsic foot muscles
· Spasticity of the digital flexors leads to clawing and reinforces the equinus through the tenodesis effect
Evaluation
· Patients commonly present with visible deformity and impaired gait
· Equinovarus position lengthens the limb – difficulty in ambulation
· Hyperreflexia and increased muscle tonus present in examination
· Associated findings: fixed contractures, calluses, pressure sores, knee hyperextension during stance
· Shoe wear difficulties, hygiene problems and cosmetic problems
Imaging
· AP, lateral and oblique radiographs should be obtained
· Useful for assessing bony alignment, fixed deformities and surgical planning
Treatment
· Treatment strategy is determined by deformity severity, flexibility, duration of neurologic injury, and functional goals
· Non-surgical
o Particularly in early phase following neuroogical injury
o Physical therapy: stretching spastic muscles, strengthening antagonists, maintaining range of motion
o Phenol or lidocaine nerve blocks: phenol provides longer lasting effect and more cost-effective than Botulinum toxin
o Botulinum toxin: easy to administer via a direct intramuscular injection
o Ankle foot orthoses are effective in mild deformities
· Surgical
o Fixed, non-braceable deformities or significant functional impairment
o Should be delayed at least 6 months to allow maximum neurological recovery
o Equinus is corrected with Achilles tendon lengthening using open or percutaneous technique
o Varus is treated with Total or Split Anterior Tibialis Tendon Transfer (SPLATT)
§ The tibialis anterior is split and the lateral half is attached to the cuboid through a drill hole and sutured in place
o Fixed varus deformity may require lateral closing wedge calcaneal osteotomy or subtalar fusion
o Toe flexor release is often necessary to address residual clawing
o Lengthening/dorsal transfer of the Posterior Tibial tendon may be necessary
o Inadvertent lengthening of PTT may result in hindfoot valgus