Posterior fusion is a standard procedure for C1/2 instability [1–5], and is indicated for a wide variety of conditions that cause atlantoaxial instability, such as inflammatory disease, trauma, degenerative disease, and anatomic anomalies. These pathological conditions often necessitate not only stabilization but also spinal cord decompression, but there are few reports that focus on the surgical technique for simultaneous decompression and fusion [6, 7]. Although conventional C1 laminectomy is the gold standard for decompression at the atlas, it provides little space for bone grafting to fuse, which is a serious deficiency when fusion is indicated. Innovations in surgical instruments have brought about remarkable progress in providing rigid initial fixation [2, 3, 5], but instrument failure, such as loosening and breakage leading to nonunion, is always a possibility [8, 9]. Bone grafting is indispensable in avoiding this complication, as permanent stability can be achieved once fusion has occurred. In this report, we introduce a new technique for achieving single-segment bone grafting, decompression, and fusion in patients with C1/2 canal stenosis. We also present two representative patients who underwent surgery with this technique, the first with an irreducible axis odontoid fracture secondary to trauma, and the second with a retro-odontoid pseudotumor.