In an AFO, which rocker is most affected by trimming the footplate proximal to the met heads?

Trimming the footplate of an ankle-foot orthosis (AFO) proximal to the metatarsal heads primarily affects the third rocker. The rockers of the foot are conceptualized points of rotation during the gait cycle, and each rocker corresponds to specific phases of foot movement.

The first rocker, which corresponds to the initial contact and loading response phases, facilitates heel strike and promotes forward progression. The second rocker becomes prominent during mid-stance, allowing for weight transfer from the heel to the forefoot. The third rocker comes into play during terminal stance, where the forefoot and toes begin to propel the body forward.

By trimming the footplate proximal to the met heads, you change the geometry and function of the AFO during the terminal stance phase. This modification can lead to an earlier lift-off of the forefoot during gait, enhancing or altering the push-off dynamics usually created by the third rocker. Consequently, since the action occurs primarily at the forefoot, which is directly influenced by how the footplate is shaped at the met heads, the third rocker is the most affected by this adjustment.

The fourth rocker is not typically considered in this context, as it involves the nuances of the toe-off phase and is further influenced by the toe