Definition Common causes include : Down syndrome Rheumatoid Arthritis Trauma Ankylosing spondylitis There are many potential causes of atlantoaxial instability. They are listed below with most common ones listed in bold: Rheumatoid Arthritis Achondroplasia Down Syndrome (occurs less frequently than atlantooccipital instability 10-20% vs 60%) (1) Grisel Syndrome Morquio Syndrome Congenital scoliosis Osteogenesis imperfecta Neurofibromatosis […]