F1 facet fracture

F1 is a non-displaced facet fracture (either superior or inferior cervical facets) from the AOSpine subaxial cervical spine injury classification system. Fracture fragments are smaller than 1 cm and comprise less than 40% of the lateral mass.

There was significant variability in diagnostic accuracy for F1 facet fracture through F3-type fractures, whereas almost universal agreement was achieved for F4-type injuries ¹⁾.