In the sitting position, the pressure of the ischial tuberosity is very large, often exceeding the normal capillary end pressure by 1 to 16 times, and is prone to ischemia to form pressure sores. In order to avoid excessive pressure here, often dig a piece of the mat at the corresponding place to make the ischial tuberosity overhead. When digging, the front should be 2.5cm in front of the ischial tuberosity, and the side should be 2.5cm outside the nodule. 

The depth of the wheelchair is about 7.5cm, and the mat has a concave shape after digging, and the notch is behind. If the above mat and the incision are used, it can effectively prevent the occurrence of pressure ulcers.