forefoot varus

forefoot varus

Metatarsus adductus Orthopedics A fixed frontal plane deformity seen when the forefoot plane is everted to the rearfoot–ie, the 5th metatarsal head is more dorsal than the 1st metatarsal head; FV can be compensated by abnormal rearfoot pronation.

forefoot varus

; inverted forefoot; varus forefoot congenital, osseous, structural deformity showing inversion of the plantar plane of forefoot relative to rearfoot, when subtalar joint is in neutral and midtarsal joint is maximally pronated about both its axes; characterized by firm resistance to a pronatory force applied to the dorsum of talonavicular joint; forefoot varus is normal in early childhood, but should not persist past 6 years of age (i.e. when developmental valgus rotation of forefoot on rearfoot is complete, and plantar aspects of fore- and rearfoot become parallel to, and on same plane as, one another); Table 1
Table 1: Features of forefoot varus
Uncompensated forefoot varusAt the midpoint of midstance:
• Plantar plane of the forefoot is inverted relative to the heel
• Plantar plane of the forefoot is inverted to the ground surface
• Calcaneum is vertical
• STJ is neutral
• MTJ is maximally pronated about both axes
Signs and symptomsFoot cannot pronate (evert) after the midpoint of midstance in order to bring the medial area of the plantar forefoot to ground contact (as there is no further pronation available at the MTJ)
Foot weight-bears throughout gait along lateral border of heel and forefoot
Excess lateral weight-bearing throughout stance
Compensatory abduction at 5 MTPJ to allow medial forefoot to weight-bear with abductory twist just after heel lift so that the heel adducts towards the midline
Hyperkeratotic lesions on the plantar skin overlying the IPJ hallux
Compensatory plantarflexion of the first metatarsal
Fully compensated forefoot varusFoot contact is normal until the midpoint of midstance:
• Calcaneum everts to allow the foot to continue to pronate after midpoint of midstance
• Forefoot is inverted but weight-bearing and parallel to the ground surface
• MTJ unlocks and the forefoot is hypermobile
Signs and symptomsThe foot distorts under load
Calcaneal eversion in static stance and from midstance to toe off with excessive STJ pronation and abduction of forefoot on rearfoot
Lowering of medial border on weight-bearing
Forefoot deformity with HAV, lesser-toe deformities and associated hyperkeratotic skin lesions
Soft-tissue pathologies such as plantar fasciitis, plantar digital neuroma, foot strains, ankle tendinopathy
Thigh, groin, shin and knee problems related to excess STJ pronation and excess internal rotation of the leg
Functional hallux limitus and low-back pain due to loss of shock-absorbing mechanisms
Partially compensated forefoot varusSome compensatory pronation available at STJ but insufficient to allow the forefoot to become weight-bearing

Note: Forefoot varus is classified according to the amount of compensatory STJ pronation available:

  • in fully compensated forefoot varus there is sufficient available STJ to reduce the deformity fully

  • in uncompensated forefoot varus there is no available STJ pronation, and thus the deformity persists throughout gait

  • in partially compensated forefoot varus there is some available STJ pronation but not enough to reduce the deformity throughout gait fully.

STJ, subtalar joint; MTJ, midtarsal joint; MTPJ, metatarsophalangeal joint; IPJ, interphalangeal joint; HAV, hallux abductovalgus.