A splinting device includes a first part for contacting a lower leg and a second part for contacting a foot hingedly connected to the first part. An adjustable attachment includes an elastic part and interconnects the first part and the second part. A method of treating plantar fasciitis includes securing the first part of the splint device to the lower leg, and securing the second part to a foot. The first part is rotated relative to the second part to establish a predetermined angle between the first part and the second part. The elastic part of the adjustable attachment, which is attached to one of the first and second parts, is stretched and attached to the other of the first part of the second part at a position based on the predetermined angle to limit movement of the first part relative to the second part beyond the predetermined angle.