1. Modeling effects of sagittal-plane hip joint stiffness on reciprocating gait orthosis-assisted gait William Brett Johnson, PhD; Stefania Fatone, PhD, BPO(Hons); Steven A. Gard, PhD

2. Aim • Determine effects of increased hip joint stiffness on gait of nondisabled persons using lower-limb paralysis simulator (LLPS). • LLPS enabled nondisabled persons to exhibit characteristics of reciprocating gait orthosis (RGO)-assisted gait • Relevance • Upright ambulation may improve quality of life for persons with lower-limb paralysis. • However, walking with RGO can be slow and exhausting. • Increased RGO hip joint stiffness may improve gait efficiency.

3. Method • While nondisabled subjects walked with LLPS at four different hip joint stiffness settings, we measured: • Hip flexion. • Crutch ground reaction forces (GRFs). • Oxygen consumption. LLPS.

4. Results • Walking speed was observed to initially increase with increases in hip joint stiffness, and then decrease. • Oxygen cost was observed to initially decrease with increases in hip joint stiffness, and then decrease.

5. Conclusion • Findings suggest that increasing hip joint stiffness may increase walking speed for RGO users.