Posting is achieved by adding a wedge to the inside or outside border of a foot orthotic to create a different alignment of the foot and ankle. Intrinsic posting is a material that is wedged at an angle and placed on top of the orthotic. Extrinsic wedging is a block of wedge material that is added externally, under the orthotic.
Intrinsic wedging must have a firm and tight fit with the foot. If the foot does not contact the orthotic well enough, the desired alignment of the foot and ankle will be lost. The base shell of the orthotic must be a perfect fit and best made from a cast of the foot.
Extrinsic posting is highly effective as even with a loose fit on an orthotic base shell, extrinsic posting will have a greater impact on the foot and ankle. A combination of both intrinsic and extrinsic posting would be ideal in cases where perfect realignment is being sought.