A knee scooter or knee walker is a two, three or four-wheeled alternative to crutches or a traditional walker as an ambulation aid. It is known by many other names, such as a knee walker, knee coaster, knee cruiser, knee caddy, orthopaedic scooter, or leg walker.
Over the years it has taken on many forms, from small-wheeled devices suitable for indoor use to larger sturdier units capable of use outside on grass or paved surfaces. Today’s version is usually a lightweight, foldable design that, with the knee flexed, supports the shin of the unusable limb. The opposite foot makes contact with the floor or ground, providing propulsion.