A new method for measurement of occipitocervical angle by occiput-C3 angle.

Background: The description of the measurement technique of the posterior occiput-third cervical spine (OC3) angle-before performing occipitocervical fusion is still controversial. Setting an appropriate alignment in occipitocervical instrumentation is important for successful fixation surgery. Several methods were used for quantifying occipitocervical alignment on the lateral radiograph.