The effect of an isocentric reciprocating gait orthosis incorporating an active knee mechanism on the gait of a spinal cord injury patient: A single case study

Objective: The aim of this study was to identify the effect of induced knee flexion during gait on the kinematics and temporal-spatial parameters during walking by a patient with spinal cord injury (SCI) through the application of an isocentric reciprocating gait orthosis (IRGO) with a powered knee mechanism.

Methods: Two orthoses were considered and evaluated for an ISCI subject with a T8 level of injury. An IRGO was initially manufactured by incorporating drop lock knee joints and was fabricated with custom molded AFOs to block ankle motion. This orthosis was also adapted with electrically-activated knee joints to provide active knee extension and flexion when disengaged.

Results: Walking speed, stride length and cadence were increased 37.5%, 11% and 26%, respectively with the new orthosis as compared to using the IRGO. The vertical and horizontal compensatory motions reduced compared to mechanical IRGO. At end of stance phase, knee joint flexion was 37.5° for the AKIRGO compared to 7° of movement when walking with the IRGO. The overall pattern of walking produced was comparable to that of normal human walking.

Conclusion: Knee flexion during swing phase resulted in an improved gait performance and also reduction in compensatory motions when compared to a mechanical IRGO.

Implications for Rehabilitation

• Powered orthosis could be used by spinal cord injury subjects.

• A major advantage of this new orthotic mechanism was regeneration of knee movement closer to that of normal human walking.

• The IRGO with a powered knee joint mechanism improved the speed of walking, step length, cadence and vertical displacement in a spinal cord injury patient which also produced near-normal knee joint angle patterns during gait.