Figure 3: A 52-year-old woman with severe rheumatoid arthritis and basilar invagination. She had previously undergone multiple prior cervical procedures done at another hospital, including placement of anterior interbody cages at C4-C6. She subsequently required occipital-cervical instrumented arthrodesis and decompression using rhBMP-2 and cancellous allograft for treatment of basilar invagination. Postoperative AP and lateral radiographs are shown in panels a and b, respectively. CT imaging with sagittal (panel c) and coronal reconstructions (panel d) performed 19 months following surgery demonstrates brisk bony fusion extending from the occipital to C1 (panel c, arrow) and along the lateral masses (panel d, arrow). Axial CT imaging at the interspace of C1-C2 does not demonstrate canal encroachment (panel e).