Drop foot is a condition that can affect individuals who have suffered a stroke, cerebral palsy, or injury to the cerebrum. It occurs when the muscles in the ankle and/or lower leg are weak, causing the foot to drop and drag during gait. The knee on the affected leg is placed under excess stress, as it will lift the leg higher in an attempt to compensate for the dragging foot. This extra loading in the knee joint puts the sufferer at an increased risk for developing osteoarthritis. Ankle foot orthoses (AFOs) are a common treatment for this condition, and our goal for this project is to use OpenSim to model the effect of stiffness, design, and placement of the AFOs with the goal of making the devices more effective.