Biomechanics foot ankle: Gait• Stance Phase Gait 60% of cycle

– Initial contact– Loading response– Midstance– Terminal Stance– Preswing

• Swing Phase Gait 40% of Cycle– Early swing– Mid-Swing– Terminal Swing

Initial Contact

• Ankle jt. is in neutral• STJ is slightly

supinated• Anterior Tibialis and

EDL are on eccentrically

Loading Response

• Ankle moves rapidly into 10 degrees PF

• Pretibial mm action• Tibia is pulled anterior• Knee flexes• STJ-Calcaneus everts

4-6 degrees (closed chain pronation)

• ?mm controls this• Midtarsals?

Loading Response

• Closed Chain Pronation: Loose packed position at STJ and in midtarsal region-allows for shock absorption– Calcaneal eversion– Talus horizontally adducts– Tibia Internally Rotates– Knee Flexes– Femur internally rotates

Midstance

• Ankle DFs to 5-10 degrees

• Gastroc & Soleus working eccentrically

• Knee extends near neutral (Gastroc stabilizes the knee)

Terminal Stance

• Ankle DFs to 10 degrees

• 1st MTP extends to 30• Calf mms still on• STJ-supinating• Midtarsals?• 1st Ray control• Knee in full extension

Terminal Stance

• Closed chain supination: subtalar joint and midtarsals go into a closed pack position. Makes a rigid lever for push off.

• Calcaneal inversion• Talar horizontal abduction• Tibial external rotation• Knee extension• Femur external rotation

PreSwing

• Knee rapidly flexing• 1st MTP 30-70 DF• Ankle to 20 degrees

PF• Lift off!

Initial Swing

• Ankle is dorsiflexing:– Eccentric contraction

of Anterior tibialis, EHL, EDL.

Midswing

• Ankle is in neutral position, dorsiflexors are still on.

Terminal Swing

• Ankle is still in neutral