C1-C2 instability

Rachis misalignment

ADI (Atlas Dens Interval): the distance between the atlas (C1) and the odontoid anterior aspect is increased to 7.3 mm (normal below 3 mm), signaling C1-C2 instability.

C1

C1 (atlas) is a ring without a body (embryologically, the C1 vertebral body fuses with C2 to become the odontoid process).

C2

C2 (axis) vertebrae is marked here with its body and arch. The odontoid process is the superior part of C2 and corresponds embryogically to the vertebral body of C1.

PADI

PADI (posterior atlas-dens interval) is measured between the odontoïd posterior aspect and C1 posterior arch. This is the available space for the spinal cord. Its is measured here at 10 mm, which is not acceptable.

Ranawat line

Ranawat line: first, draw a line between the anterior aspect of C1 and its posterior arch, then mark a point in the odontoid at the C2 pedicles level. Ranawat line is the distance between this point and the C1 line and is measured here at 8 mm (normally of 15 mm in men and 13 mm in women), thus significantly decreased.

Pannus

Rheumatoid arthritis

Irregular hyperdensities

This C1-C2 instability and the presence of calcifications in the C1-C2 articular space are highly suggestive of an important rhumatoïd pannus.

Discarthrosis

Joint space narrowing

Multiple important intervertebral joint narrowing and osteophytes at C5-C6 and C6-C7 secondary to degeneration.

Uncarthrosis

Joint space narrowing

Moderate C5-C6 and C6-C7 uncarthrosis more pronounced on the left side than on the right. Unco-vertebral joints are often the sites of degenerative changes.

Dental fillings

Six dental fillings can be seen.