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Equinovarus Deformity

- See:
      ankle equinus:
      cerebral palsy

- Discussion:
    - more common in spastic hemiplegia, and is caused by overpull of of the tibialis posterior and/or anterior tibial tendons;
           - try to determine which of these muscles is more pathologically involved;
           - remember that the tibialis anterior is normally active at heel strike and thru out swing phase where as the tibialis posterior normally activates just
                  after heel strike and stays active thru out stance phase;
           - children w/ hemiplegia often display equinovarus foot deformity as result of posterior tibial tendon dominance, although anterior 
                  tibial tendon is occassionally at fault;
    - dynamic varus deformities of foot are most often due to spasticity of tibialis posterior (active in stance phase) or anterior  tibial muscle 
                  (active in the swing phase);
    - etiology in adults:
           - stroke;
           - parkinson's disease;
           - focal dystonia;
                  - may present as torticollis, writer's cramp, and less often it involves the leg (as equinovarus);

- Treatment:
    - transfer of an entire muscle (posterior or anterior tibialis) is rarely indicated;
          - entire transfer of posterior tibial tendon to dorsum of foot should be avoided unless EMG show that it is active only during the 
                  swing phase of gait;
                  - transfer of a PT tendon w/ normal phase activity (active in stance), will produce a calcaneovalgus foot from chronic tonic activity;
    - split muscle transfers are helpful, especially when the affected muscle is spastic in both stance and swing phases of gait;
    - split posterior tibial tendon transfer:
          - split posterior tibialis transfer involves rerouting half of the tendon dorsally to the peroneus brevis;
                  - advantage is that the strength of plantar flexion is preserved;
          - split posterior tibial tendon transfer, combined with heel cord lengthening, is used in cases w/ spacicity of muscle, flexible varus foot, and weak peroneals;
          - it remains an alteranative to the traditional lengthening of posterior tibial tendon;
                  - lengthening of the posterior tibialis is now rarely indicatated because of recurrence and development of a calcaneovalgus foot;
          - alternative procedure involves transfer of posterior tibial tendon through interosseous membrane to dorsum of lateral portion of cuneiform bone;
                  - most poor results will result from residual varus deformity;
          - complications include decreased foot dorsiflexion;
          - reference:
                  - Posterior tibial tendon transfer and tendo-Achilles lengthening for equinovarus foot deformity due to severe crush injury.
    - split anterior tibial transfer:
          - indicated when the tibialis anterior is active both in stance and swing phase (normally on active in swing phase)
          - combined split anterior tibial tendon trasfer and IM lengthening of posterior tibial tendon (Barnes and Herring) has been recommended for
                    dynamic varus of hindfoot and adduction of forefoot in both stance and swing phase of gait;
          - split anterior tibialis transfer is used when forefoot supination is predominant, and usually is combined with posterior tibial tendon lengthening;
          - split anterior tibialis transfer (rerouting half of tendon posteriorly to the cuboid) is used in patients with spasticity of muscle and flexible varus deformity;
          - usual approach is lengthening of Achilles tendon, often w/ split transfer of the anterior tibial tendon;
                  - tendo-achilles lengthening addresses the equinus deformity;
                  - split tibialis anterior transfer adresses hindfoot varus deformity;
          - occassionally the posterior tibial tendon must be lengthened;
          - complications:
                  -  patients who demonstrate a strong contraction of the TA during swing phase before surgery may develop a drop foot following surgery;
                          - this occurs because the TA transfer reduces dorsiflexion;
                          - recurrence of varus deformity will occur in aboutt 15%;
                  - complications of this procedure include over correction;
    - extrinsic toe flexor release:
          - release of the FHL and FDL lessens the toe flexion that occurs with dorsiflexion or the foot;
    - anterior transfer of long toe flexors (FHL and FDL):
          - indicated for adult patients who have had a stroke;
          - procedure is often combined with tendo Achilles lengthening;
          - motivation for this procedure is based on the EMG observation that the long toe flexors in these patients shows a relatively high 
                 incidence of muscle actively inthe swing phase;
          - using this procedure, about 75% of patients will be able to walk without an AFO;
          - tendons of the FHL and FDL are transferred anteriorly to the 4th metatarsal through the interosseous membrane of the lower leg;
          - FHL tendon is passed around the base of the 4th metatarsal to make a loop by suturing it to the FDL tendon under maximum tension;
          - when the hindfoot varus deformity is severe, consider lengthening the posterior tibial tendon;
          - recurrence of varus deformity will occur in aboutt 15%;

- Fixed Deformity:
    - for rigid heel varus, lateral closing wedge osteotomy should be combined with soft-tissue balancing;
    - triple arthrodesis remains an alternative procedure for a symptomatic, rigidly deformed foot, especially in adolescent

Posterior tibial tendon transfer through the interosseous membrane to correct equinovarus deformity in cerebral palsy. An initial experience.

Split posterior tibial-tendon transfers in children with cerebral spastic paralysis and equinovarus deformity.

Posterior tibial-tendon transfer in patients with cerebral palsy.

Combined split anterior tibial-tendon transfer and intramuscular lengthening of the posterior tibial tendon. Results in patients who have a varus deformity of the foot due to spastic cerebral palsy.

Medial calcaneal osteotomy for relapsed equinovarus deformity. Long-term study of the results of Frederick Dwyer.

Split posterior tibial tendon transfer in spastic cerebral palsy.  

Valgus and varus deformities of the foot in cerebral palsy.  

Split posterior tibial tendon transfer for spastic equinovarus foot deformity.

Operative management of foot and ankle equinovarus associated with focal dystonia.

Effects of Tensioning Errors in Split Transfers of Tibialis Anterior and Posterior Tendons.

Surgical correction of foot deformities after stroke.

Orthopaedic management of the stroke patient.  Part II. Treating deformities of the upper and lower extremities.                  

Surgical correction of gait abnormalities following stroke.  

Effect of Attachment Site and Routing Variations in Split Tendon Transfer of Tibialis Posterior.

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