Atlanto-axial subluxation in rheumatoid arthritis.

In 1969 the results of a survey of atlanto-axial subluxation in all seventy-six consecutive rheumatoid patients attending a clinic were published (Mathews, 1969). Abnormal separation of the odontoid process from the anterior arch of the atlas was found in nineteen (25%) patients and was found to be more common in patients with more serious forms of the disease. In addition, an abnormal vertical relationship of the tip of the odontoid process to the base of the skull was found in six (8%) patients. A curious discrepancy between the amount of subluxation and the presence of neurological damage led to the supposition that this finding could often be relatively innocuous and indicated the need for a follow-up study to clarify the natural history of rheumatoid disease in this region.