The paraplegic patient maintains a standing posture called the C‐posture by using a knee–ankle–foot orthosis with medial single hip joint, which also helps the patient to perform stable arm movement. The purpose of this study is to reduce the burden on paraplegic patients in walking with the orthotic. The elastic mechanism capable of providing mobility to the foot joint is investigated. The realization of the C‐posture and adequate system parameters are analyzed. The C‐posture is considered as the equilibrium point attractor in the musculoskeletal dynamics of paraplegic patients, and the dynamics of paraplegia is applied to the analysis. Return map analysis is used in the search for the equilibrium point attractor and in the stability analysis. A simulation for two‐point reaching movement of the upper extremity is tested, and the feasibility of the idea is investigated. The simulation shows that a stable posture similar to the C‐posture is realized even if the foot joint is stabilized by using elasticity, and that upper extremity movement can be realized without falling over. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(5): 1–12, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20239