Fig. 1From: Sacroiliac joint variation associated with diffuse idiopathic skeletal hyperostosisVariation of sacroiliac joint changes on computed tomography. Type 1, normal or tiny peripheral bone irregularity; Type 2, subchondral bone sclerosis and osteophytes formation; Type 3, vacuum phenomenon of SI joint; Type 4, bridging osteophyte and bony fusion of SI jointBack to article page