What preparation of a positive cast is done for the purpose of offloading pressure, in creating a custom orthotic device for a diabetic patient with a plantar midfoot ulcer?

When creating a custom orthotic device for a diabetic patient with a plantar midfoot ulcer, the goal is to offload pressure from the affected area to promote healing and prevent further complications. Option B involves adding plaster to the positive cast in the area of the ulcer. This technique effectively raises that specific area on the orthotic, thereby redistributing weight and reducing pressure directly on the ulcer.

Raising the area around the ulcer allows for a cushioning effect, which is essential in managing plantar ulcers, particularly in diabetic patients who are more prone to foot complications. This method ensures that the ulcer is not subjected to pressure from walking or standing, facilitating healing.

In contrast, options that involve adding plaster to the negative cast or removing plaster from the positive cast would not achieve the desired outcome of offloading pressure effectively. Adding to the negative would not provide the necessary relief, and removal might increase pressure on the ulcer, exacerbating the situation rather than alleviating it. Therefore, adding plaster to the positive cast is the most appropriate preparation to create an effective custom orthotic for this patient.