Biomechanics foot ankle: Gait Stance Phase Gait60% of cycle –Initial contact –Loading response –Midstance –Terminal Stance –Preswing Swing Phase Gait40% 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 1 st MTP extends to 30 Calf mms still on STJ-supinating Midtarsals? 1 st 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 1 st MTP 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