sanders classification sanders classification in orthopedic medicine, the sanders classification is a system of categorizing intra-articular calcaneal fractures based on the number of articular fragments seen on the coronal ct image at the widest point of the posterior facet. classification type description i nondisplaced posterior facet ii displaced with one fracture line in the posterior facet iii displaced with two fracture lines in the posterior facet iv comminuted with more than three fracture lines in the posterior facet