The use of scoliosis orthoses for adolescent idiopathic scoliosis (AIS) treatment originated in the 1930s to 1940s, and in the last few decades orthotic treatment has been shown to modify the natural history of AIS and reduce the incidence of surgery. Although the biomechanical principles of orthotic treatment are well established, the magnitude of the forces exerted by orthoses and the optimal orthotic design are not well understood. This article provides a review of past orthotic biomechanical research to inform conservative treatment of AIS.