RollerAid RollerAid from Therapeutic Dimensions is a knee scooter that acts as a substitute for crutches. It is designed for use by patients with below-the-knee injuries. It includes swiveling front casters, a handy basket and a water bottle carrier, all designed to accommodate an active lifestyle during recovery. It is collapsible for easy transport and is suitable for use around the home or at work on level surfaces. RollerAid supports patients up to 350 pounds.