Fig. 2

A rheumatoid arthritis with BI managed with posterior structural fusion. Female, 41 years. She reported a history of rheumatoid arthritis for 16 years. Symptoms of myelopathy lasted for 1 year (JOA score 9). She underwent occipital-C4 fixation, release of the atlantoaxial facets, and intraarticular structural fusion. Her JOA score improved to 15 at the final follow-up. A–C Preoperative CT slice: The right atlantoaxial facet joint (2A), midsagittal (2B), and left atlantoaxial facet joint (2C) views showed the relationship among C0, C1, and C2. The distance from the tip of the odontoid process to Mcrea’s line was 12.7 mm, and the secondary BI was due to RA-induced collapse of the lateral mass column. D–F Immediate postoperative CT slice: Structural grafts were inserted into facet joints with heights of 6.8 mm on the right side (2D) and 9.7 mm on the left side (2F, white double arrow), and the BI was lessened to 5.7 mm (2E). G–I CT at 5 months following surgery: Both the BI correction (6.5 mm, 2H) and the height of the joint space (6.5 mm at right, 2G; 8.5 mm at left, 2I) were maintained well, and robust interfacet fusion was acquired