Case of the Week - Patient Summary 5640Peer Reviewed and Certified -
Traumatic transverse ligamentous disruption
Atlanto-axial Subluxation in Rheumatoid Arthritis Atlantoaxial subluxation is caused by both ligamentous and bony changes. Loss of integrity in the transverse ligament is the major pathologic change and is often associated with bony erosion at the insertion site of the ligament on the dens. Also, joint capsule destruction and granulation formation occur between the C1-C2 lateral masses. These pathologic changes lead to anteroposterior and, to a lesser degree, rotatory luxation.
As demonstrated by dynamic (flexion/extension) cervical spine radiographs, the atlanto-odontoid distance provides a measurement of atlantoaxial instability. Intervals greater than 3 mm are abnormal, and those greater than 7 to 8 mm are associated with cervical myelopathy. Indications for surgery to correct rheumatoid atlantoaxial instability include neurologic deterioration and intractable pain. In patients with severe atlantoaxial instability and stable or no neurologic deficits, the indications for surgery are less clear though an atlanto-odontoid interval of 8 mm or greater is commonly used.
