Congenital laxity of the transverse atlantal ligament producing atlanto-axial subluxation: a case report

摘要

An anterior atlanto-dental interspace (ADI) of greater than 3mm in an adult indicates atlanto-axial subluxation (AAS) and instability. A number of pathological processes are known to cause AAS. Trauma, specifically injuries with a component of hyperflexion, may produce sprain or avulsion of the transverse atlantal ligament (TAL). More often, however, the odontoid process will fracture before the tough TAL ruptures, so that isolated rupture of the ligament is generally considered to be rare. Inflammatory arthritis or infection may erode and weaken or destroy this ligament. Focal or global congenital conditions are also associated with TAL laxity or agenesis and subsequent AAS. Congenital laxity of the TAL is a diagnosis of exclusion which may be made only after a comprehensive search for other causes of AAS.