K is for Kirby Skive
You may call it a Kirby Skive or a medial heel skive. This interesting accommodation is constructed by removing small amounts of the medial portion of the plantar heel of the positive cast of the foot to create a varus wedging effect within the heel cup of the orthosis. Extrinsic rearfoot posting is required to maintain rear foot stability. Intrinsic heel pads cannot be used with medial skives.
The Kirby Skive allows for increased ground reactive forces through the custom orthotic on the medial plantar side of the calcaneus and will thereby decrease the eversion of the heel.
The size of the medial heel skive is determined in millimeter increments. The greater the amount, the greater the varus wedging in the heel cup. This provides a greater force exerted to cause supinatory movement.
Kirby Skives can improve pronation control on flexible flat feet, PTTD (Stage I and Stage II) and other types of excessively pronated feet.
Medial skives are not recommended for patients with lateral ankle instability, lateral heel pain and thin heel fat pads.