Figure 1c Figure 1d Figure 1e
Fusion between the C1 and C2 vertebrae in 2 patients with KFS and fusion between only C2 and C3 vertebrae in the remaining 36 cases with KFS were observed 21 patients with KFS had bilateral AOA, 1 had left partial AOA, 10 had odontoid hypoplasia (OH), 11 had basilar invagination (BI), 6 had Arnold Chiari (AC), 1 had AOD, 9 had ADD, 3 had rotatory AAD, 5 had MM, and 4 had coexisting syringomyelia (Figure 2 a-e). 15 patients with KFS had a posterior arch defect in the C1 vertebra and 4 had an anterior arch defect (Table 1).