Fig. 3

Grading scale for osteoarthritis of the atlantoaxial (C1-2) facet joints. Grade 0 = normal. Grade 1 = joint space narrowing. Grade 2 = narrowing plus sclerosis. Grade 3 = severe osteoarthritis with narrowing, sclerosis, and osteophytes
Grading scale for osteoarthritis of the atlantoaxial (C1-2) facet joints. Grade 0 = normal. Grade 1 = joint space narrowing. Grade 2 = narrowing plus sclerosis. Grade 3 = severe osteoarthritis with narrowing, sclerosis, and osteophytes