The majority of people with muscle weakness or paralysis lose their ability to walk and require various assistive devices like a walker to walk. Although various studies have examined the effect of different types of anterior and posterior walkers on different walking variables, so far no studies compare anterior versus posterior walker on forces and torques applied to the lower extremities. This paper presents a novel approach of using a passive saddle-assistive device (S-AD) to investigate the effect of this device on the torques of the joints. To measure the effectiveness of the device, a volunteer with spinal cord injury (SCI) participated to walk in four modes; including the use of a standard walker, anterior, and posterior mobility S-AD with and without body weight support, in the gait laboratory. The forces and torques applied to the lower and upper limbs were measured and examined. The result demonstrated a reduction in the vertical force on the lower limb in the anterior S-AD in supporting the patient's weight compared to the standard walker up to 42.8% and to the posterior S-AD with weight support up to 12%. According to the results, the anterior S-AD has a greater effect compared to posterior S-AD and standard walkers on lower and upper limb torque and forces during walking of a SCI patient while using knee ankle-foot orthoses.