3D-printed patient-specific guides improve screw accuracy in upper cervical spine surgery: a comparative study - Guoqi Niu; Yalong Guo; Gong Zhou; Yang Gao; Weili Jiang; Hui Chen; Hu Nie; Tao Liu; Zheng Sun; Jiawei Cheng; Yi Yang; Jianzhong Bai (Frontiers in Neurology, 2026)