Ossification of the transverse atlantoid ligament in rheumatoid arthritis.

Ossification of the transverse atlantoid ligament (TAL) is rare. A few cases have been reported by Wackenheim and Dietemann and others. Calcification of the TAL has also been seen in calcium pyrophosphate dihydrate deposition disease. It is important to differentiate this condition from traumatic lesions of the dens axis.