Transcript Ankle and foot

ESS 303 – Biomechanics
Ankle and Foot
Tibiofibular Joint
Similar to radioulnar joint
Superior tibiofibular joint
Middle tibiofibular joint (interosseus
membrane)
Inferior tibiofibular joint
Rotational movements not called
pronation or supination
Ankle Joint
 Distal tibia and fibula articulates with talus
 Hinge joint – sagital plane
 Flexion – dorsiflexion (about 20°)
 Extension – plantarflexion or volar flexion (30-50°)
 Some transverse plane (rotational) movement
possible
 7° medial, 10 ° lateral
 Some frontal plane (side-to-side tilt) movement
possible
 ≈ 5 ° frontal talar tilt
Foot Positions
Subtalar or talocalcaneal joint
Inversion & eversion
Pronation = ankle dorsiflexion +
subtalar (calcaneal) eversion + forefoot
abduction (external rotation)
Supination = ankle plantarflexion +
subtalar (calcaneal) inversion + forefoot
adduction (internal rotation)
Foot Positions
Arches of the Foot
Arches of the Foot
Arch Positions
Normal
High arch: Pes
cavus
Low arch (flat
foot): Pes planus
Ankle Joint Stability
Distal ends of tibia and fibula – like
mortise (pinchers) of adjustable wrench
Tibia is weight bearing
Fibula is considered non-weight bearing
– may hold up-to 10% of body weight
Multiple ligaments
Ligaments and Sprains
Ligaments and Sprains
Return to Activity
Must have complete range of motion and
at least 80-90% of pre-injury strength
before return to sport
If full practice is tolerated w/out insult,
athlete can return to competition
Must involve gradual progression of
functional activities, slowly increasing
stress on injured structure
Movements & Major Muscles
Dorsiflexion: Tibialis anterior
Plantar flexion: Gastrocnemius &
soleus
Inversion: Tibialis anterior, peroneus
longus & peroneus brevis
Eversion: Peroneus tertius
Biomechanics of Gate
 Stance phase (60-65%)
 Heel contact (heel strike or initial contact)
 Foot flat (loading response)
 Mid stance
 Heel off (terminal stance)
 Toe off
 Swing phase (35-40%)
 Toe off (acceleration or initial swing)
 Mid swing
 Heel contact (deceleration or terminal swing)
Single Limb Weight Bearing
Pelvis forms a 1st class lever
Hip is fulcrum, resistance force is body
weight, effort force is from abductors and
adductors
Body is drawn over supporting leg by
adductor muscles
Hip abductors of the support leg prevent
the pelvis from dropping on the opposite
(unsupported) side
Knee Joint and Gate
Knee Joint and Gate
Chimpanzee:
medial and lateral
condyle similar
Human: medial
condyle larger
than lateral
condyle – allows
COM to shift over
foot
Advantages/disadvantages to Bipedal
Locomotion
Disadvantages
Loss of speed
Loss of agility
Advantages
Carry food
Carry tools
Increased ability to nurture/protect offspring
Enable to give birth more often