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Department
of Podiatry
Rearfoot
varus
Definition
- fixed, osseus congenital deformity in which
the tibia has formed in a bowed position or the subtalar joint has
formed in a position in which the calcaneus is inverted when the STJ
is held in its neutral position and the MTJ is locked
- rearfoot varus
- tibial varum
- subtalar varus
- >4° in 98% of the population (McPoil, 1988)
- RFV = TV + STV
Aetiology
Tibial varum
- failure of tibia to straighten from infantile position
- whole tibia or distal third
- genu varum
- Blount's disease: lateral slippage of proximal tibial epiphysis
Subtalar varus
- retention of varus calcaneal torsion
- wedge-shaped talus
- uneven epiphyseal growth
- all three are clinically indistinguishable
Pathomechanics
- whole foot in inverted position
- requires eversion to bring medial border to the ground
- occurs via STJ pronation
Degree of compensation:
- size of the deformity
- available ROM at STJ
Uncompensated rearfoot varus
- uncommon as a developmental condition
- post-surgical or post-traumatic fusion
- inadequate STJROM
- foot strikes laterally, and remains in inverted position
- first ray may plantarflex to bring medial border of foot to the
ground
- inadequate shock absorption
- medial knee pain, hip pain, back pain
- lateral instability
- inversion ankle sprain
- excessive lateral WB
- HK 5th MPJ, lateral heel
- lateral shoe wear
Fully compensated rearfoot varus
- sufficient STJROM to bring medial border of foot to the ground
- rapid (less than 0.15 secs) contact phase pronation, generates large
pronatory torque
- pronation required until heel lift
- results in forefoot hypermobility, overuse of supinator musculature,
delayed resupination
- medium arch height non-WB with slight lowering on WB
- excessive lateral shoe wear
- Haglund's deformity
- tendinitis of supinator musculature
- all other pathologies associated with excessive STJ pronation
Orthotic management
- decrease need for compensation
- medial rearfoot posting
- has been found to limit total range of STJ pronation, decrease pronation
velocity, alleviate symptoms associated with pronation-induced pathology
Summary
- osseus deformity
- rearfoot varus
- tibial varum
- subtalar varus
- whole foot in inverted position
- requires eversion to achieve medial forefoot contact
- STJ pronation
- first ray plantarflexion
- rapid contact phase pronation
 References
Michaud TC (1993) Foot orthoses and other
forms of conservative foot care. Williams and Wilkins, Baltimore,
pp.93-105.
Root ML, Orien WP and Weed JH (1971) Clinical biomechanics: normal
and abnormal function of the foot. Clinical Biomechanics Corp,
Los Angeles, Chapter 10.
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