Engineering design considerations of the ORLAU Swivel Walker

A Swivel Walker enables paraplegic patients with spinal lesions between L1 and C6 to ambulate in the upright position without the use of crutches or other walking aids. It consists of a rigid body structure, which provides internal stabilization of ankles, knees, and hips, mounted on swiveling footplates which give external stabilization and a means of injecting propulsive forces in a controlled manner. When standing the width of the support area is small to facilitate easy lateral rocking, but the potential support area afforded by the inclined footplate mounting is large which ensures external stability. To ambulate the patient rocks alternatively onto each footplate by making use of inertial reaction as his trunk contacts the supporting framework of the swivel walker. This in itself will not produce forward or backward motion, but three mechanisms can be invoked to achieve the desired result: (a) Gravitational propulsion; (b) Inertial reaction; (c) Inertial torque. The open frontal aspect and plastic chute have enabled many patients to achieve full independence. It makes doff and don in particular very easy for a patient in a wheelchair using the technique illustrated in the article.