1. ESS 303 – Biomechanics Ankle and Foot

4. Tibiofibular Joint Similar to radioulnar joint Superior tibiofibular joint Middle tibiofibular joint (interosseus membrane) Inferior tibiofibular joint Rotational movements not called pronation or supination

5. 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

6. 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)

7. Foot Positions

10. Arches of the Foot

12. Arch Positions Normal High arch: Pes cavus Low arch (flat foot): Pes planus

13. 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

14. Ligaments and Sprains

16. 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

17. Movements & Major Muscles Dorsiflexion: Tibialis anterior Plantar flexion: Gastrocnemius & soleus Inversion: Tibialis anterior, peroneus longus & peroneus brevis Eversion: Peroneus tertius

18. 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)

20. 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

22. Knee Joint and Gate

23. Chimpanzee: medial and lateral condyle similar Human: medial condyle larger than lateral condyle – allows COM to shift over foot

24. Disadvantages Loss of speed Loss of agility Advantages Carry food Carry tools Increased ability to nurture/protect offspring Enable to give birth more often Advantages/disadvantages to Bipedal Locomotion