Lower limb wearable robotics also known as exoskeleton or power suit is a booming field of research. Potential medical applications cover a large range of gait disorders from rehabilitation to assistance in daily mobility. Surprisingly, or not, paraplegia seems to be the first target of all commercialized exoskeleton. In this paper we will try to understand this choice and look at other disorders leading to the inability to walk. Neuromuscular, autoimmune or neurological diseases such as muscular dystrophy, multiple sclerosis or stroke, can lead to similar gait disorders and are mostly incurable today. SCI (Spinal Cord Injury) symptoms are quite dissimilar from theirs and reveal specific design challenges. Existing devices' architecture and human-robot interaction are presented and discussed in terms of adaptation toward non-SCI disorders.