A heel post modification primarily affects which phases of stance?

A heel post modification is a specific adjustment made to the heel section of an orthotic or footwear, often used to improve alignment and stability during gait. This modification directly influences how the foot interacts with the ground during the initial contact and mid-stance phases of the walking cycle.

In the contact phase, the heel strikes the ground, and the position and orientation of the heel are crucial for distributing forces appropriately and absorbing impact. A heel post modification can alter the angle or stability of the rearfoot, helping ensure that the foot strikes in an optimal position.

During the mid-stance phase, the body weight transfers over the foot, and maintaining proper alignment through the heel is essential to ensure that the body's center of mass is effectively controlled. The heel post helps in keeping the foot more stable and aligned, thus promoting a smoother weight transition and preventing excessive motion or strain.

These phases are primarily influenced by adjustments made to the heel, which is why the correct answer highlights contact and mid-stance, as these are the key moments where the heel's position significantly impacts overall stability and movement dynamics. Other phases like propulsion involve more than just heel positioning, focusing on forefoot engagement and push-off mechanics.