A custom-made ankle/foot orthosis for the treatment of patients having plantar ulcers and foot deformities is disclosed, which comprises a rigid L-shaped support member and a rigid anterior support shell hingedly articulated to the L-shaped support member. The plantar portion of the L-shaped member further comprises at least one ulcer-protecting hollow spatially located for fitted placement in inferior adjacency to a user's plantar ulcer, thus allowing the user to transfer the user's weight away from the plantar ulcer and facilitating plantar ulcer treatment. The anterior support shell is designed for lateral hinged attachment to the L-shaped member to take advantage of medial tibial flare structure for enhancing the weight-bearing properties of the disclosed orthosis. Leg securement structure attaches the anterior support shell to the L-shaped member in fixed, weight-bearing relation about the proximal, anterior portion of the user's lower leg.