Gait & basic foot kinematics

Gait cycle

  • stance phase (62%)
    • 3 components
      • heel strike, foot flat & toe off
  • swing phase (38%)
  • double legged support (12%) followed by an intermediate phase (38%) then another period of double legged support
  • In running there is no period of double legged support; indeed there is a float phase when neither foot is in contact with the ground
  • During Gait
    • centre of mass (anterior to S2) moves 5cm laterally

Shock absorption

  • Ground reaction forces during walking reach 1.5 times body weight. During running they are 3 times body weight
  • Shock absorption by the hindfoot, ankle & motors acting across them is very important to reduce stresses across the leg & back
  • Factors involved are
  • Static structures
    • Heel pad
  • Dynamic structures
    • Eccentric contractions of muscles e.g. tibialis anterior
      • Controlled descent of the forefoot after heel strike is the most important function of tibialis anterior
      • Absence of tib anterior function results in foot slap
    • Tibialis posterior
      • Contraction results in controlled hindfoot eversion
    • Gastrocsoleus
      • Controls forward motion of the tibia relative to the foot
  • Change in vectors – the axial load of impact is dissipated by partly converting it to a rotatory load, as the talus & tibia internally rotate on heel strike

Accommodation to surface irregularities

  • Achieved by the freedom of movement in the subtalar & transverse tarsal joints

Push off

  • At push off the flexible foot converts to a rigid one, to allow propulsion
  • How does this occur?
    • At foot strike the tibia internally rotates, the calcaneus assumes a valgus posture & the subtalar joint everts
    • As the pelvis rotates towards the stance foot the tibia externally rotates
    • This causes external rotation of the talus, in particular its head
    • This results in the orientation of the axes of the talonavicular joints & the calcaneocuboid joints changing from parallel to divergent
    • divergent axes lock the transverse tarsal joint & make the foot rigid
    • calcaneus assumes a varus posture & the subtalar joint inverts
  • Other factors
    • Tightening of the plantar fascia via the windlass effect: the fascia arises from the medial side of the calcaneus & as it tightens it pulls the calcaneus into varus
    • Contraction of Tibialis Posterior which holds the navicular medially on the talar head
    • Contraction of the peroneus longus which plantar flexes the first ray

Columns of the foot

  • medial column consists of the medial navicular, medial cuneiform & 1st MT
  • middle column consists of the lateral navicular, intermediate & lateral cuneiforms & the 2nd & 3rd MT
  • lateral column consists of the cuboid & the 4th & 5th MT

Webpage Last Modified: 18 February, 2010
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