Case Report

Gait Analysis before and after Gastrocnemius Fascia Lengthening for Spastic Equinus Foot Deformity in a 10-Year-Old Diplegic Child

Table 4

Ankle rockers.

Ankle Rockers description

First rockerIt is referred to as the heel rocker. It begins at initial contact and extends through loading response. In normal gait the fulcrum of this rocker is the heel. Posterior protrusion of the heel creates a level equal to 25% of the foot total length and because the ground reaction force acting on this level is passing through the heel at initial contact, its immediate effect is to thrust the entire foot towards the floor. This external moment is resisted by the internal moment of the pretibial muscles. The purpose of the first rocker is shock absorption, that is, to decelerate the body’s inertia at initial contact.
Second rockerIn this period the fulcrum has moved from the heel to the centre of the ankle joint as the tibia hinges forward on the stationary foot. The purpose of the second rocker is to control the position of ground reaction force referable to the joints above.
Third rockerIn this period the fulcrum has moved forward from the ankle to the metatarsal heads. The deceleration of the first two rockers is balanced by the acceleration produced by the third one.