Reclining or tilt-in-space wheelchairs have seating surfaces which can be tilted to various angles. The original concept was developed by an orthotist, Hugh Barclay, who worked with disabled children and observed that postural deformities such as scoliosis could be supported or partially corrected by allowing the wheelchair user to relax in a tilted position. The feature is also of value to users who are unable to sit upright for extended periods for pain or other reasons.
In the case of reclining wheelchairs, the seat-back tilts back, and the leg rests can be raised, while the seat base remains in the same position, somewhat similar to a common recliner chair. Some reclining wheelchairs lean back far enough that the user can lie down completely flat. Reclining wheelchairs are preferred in some cases for some medical purposes, such as reducing the risk of pressure sores, providing passive movement of hip and knee joints, and making it easier to perform some nursing procedures, such as intermittent catheterization to empty the bladder and transfers to beds, and also for personal reasons, such as people who like using an attached tray. The use of reclining wheelchairs is particularly common among people with spinal cord injuries such as quadriplegia.
In the case of tilting wheelchairs, the seat-back, seat base, and leg rests tilt back as one unit, somewhat similar to the way a person might tip a four-legged chair backwards to balance it on the back legs. While fully reclining spreads the person's weight over the entire back side of the body, tilting wheelchairs transfer it from only the buttocks and thighs (in the seated position) to partially on the back and head (in the tilted position). Tilting wheelchairs are preferred for people who use molded or contoured seats, who need to maintain a particular posture, who adversely affected by sheer forces (reclining causes the body to slide slightly every time), or who need to keep a communication device, powered wheelchair controls, or other attached device in the same relative position throughout the day. Tilting wheelchairs are commonly used by people with cerebral palsy, people with some muscle diseases, and people with limited range of motion in the hip or knee joints. Tilting options are more common than reclining options in wheelchairs designed for use by children.