Single Limb Stance



- See: Stance Phase:

- Discussion:
    - single limb stance comprimises 38% of gait cycle;
    - during single limb stance, the ankle begins to dorsiflex by motion of tibia over the fixed foot;
    - early phase:
           - subtalar joint is pronated inorder to absorbe shock;
           - muscles remain quiet;
    - middle phase:
           - ankle continues to dorsiflex;
           - stability is controlled by ligaments, aponeurosis, & extrinsic muscles primarily during the period of single limb stance from initation to 
                  about 30% of the gait cycle;
           - muscle activity during gait:
                  - gastroc-soleus, posterior tibialis, peroneal, and toe flexor muscles show electrical activity;
                  - intrisic muscles of foot begin to contract as ankle joint reaches maximum dorsiflexion;
                  - gastroc-soleus activity is to control the forward progression of tibia;
                  - length of contracting muscle w/ forward position of tibia and body cause heel rise to occur;
                  - peroneal muscles become active w/ eccentric activity at midstance
    - late phase:
           - external rotation of the tibia accompanies this motion, which has a subsequent effect on hindfoot and transverse tarsal motion;
           - hindfoot and mid foot invert to accommodate the external rotation transmitted from the tibia;
                  - sub-talar joint continues inverting from previous everted range to neutral position;
           - toe dorsiflexion begins, which stabilizes arch of foot by windlass mechanism;
                  - elevation of the arch occurs with dorsiflexion of the great toe;
                  - this maintains the foot as a somewhat rigid lever



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, September 9, 2011 12:15 pm