(1) Seat Width: Measure the distance between the two buttocks or thighs when seated, and then add 5cm, which will leave a 2.5cm gap on each side after sitting down. If the seat is too narrow, it will be more difficult to get on and off the wheelchair, and the buttocks and thigh tissues may be compressed; if the seat is too wide, it will be hard to sit stably, inconvenient to operate the wheelchair, and the limbs can easily get tired. Moreover, entering and exiting doorways could also become challenging.
(2) Seat Length: Measure the horizontal distance from the back of the buttocks to the back of the calf muscle when seated, and then subtract 6.5cm from the result. If the seat is too short, most of the body weight will fall on the ischial tuberosities, leading to excessive pressure in that area. If the seat is too long, it will compress the popliteal fossa, affecting local blood circulation and easily irritating the skin there. For patients with shorter thighs or hip/knee flexion contractures, using a shorter seat would be better.
(3) Seat Height: Measure the distance from the heel (or shoe heel) to the popliteal fossa when seated, and then add 4cm. When placing the footrest board, ensure that the surface is at least 5cm above the ground. If the seat is too high, the wheelchair cannot approach the table; if the seat is too low, the ischial tuberosities will bear too much weight.
(4) Cushion: To ensure comfort and prevent bedsores, a cushion should be placed on the wheelchair seat. Common cushions include foam rubber pads (5-10cm thick) or gel pads. To prevent the seat from sinking, a 0.6cm thick plywood can be placed under the cushion.