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