Open Reduction for Potentially Reducible Atlantoaxial Dislocation Secondary to Transverse Ligament Laxity in Patients with Rheumatoid Arthritis

Abstract

Atlantoaxial dislocation (AAD) is classified into reducible AAD and irreducible AAD (IRAAD). Anterior or posterior releasing followed by occipitocervical/atlantoaxial fusion is often performed for IRAAD, but is technically demanding. This study aimed to evaluate the results of the posterior open reduction technique without releasing the atlantoaxial joint in the treatment of potentially reducible AAD (PRAAD) caused by transverse ligament laxity in patients with rheumatoid arthritis (RA). Data from 38 RA patients who experienced PRAAD due to transverse ligament laxity were retrospectively reviewed. They all underwent posterior open reduction and fusion without releasing the atlantoaxial joint. Outcomes were evaluated by using atlantodental interval, modified Japanese Orthopedic Association scores, Nurick grade, Neck Disability Index, and visual analog scale score for neck pain. All the patients achieved solid bone fusion at follow-up. The mean atlantodental interval was reduced to 5.6±0.7mm and 2.1±0.5mm after traction and operation, respectively, from a preoperative score of 8.2±0.6mm(P<0.05). Compared with the respective preoperative values, the mean modified Japanese Orthopedic Association score and Nurick grade were significantly increased at the final follow-up (both P<0.05), whereas the Neck Disability Index and visual analog scale score for neck pain were significantly decreased (both P<0.05). AAD with partial reduction after skeletal traction for 48hours should be defined as PRAAD, not IRAAD. Open reduction with a C1-C2 pedicle screw-rod system can be safely and effectively applied in the treatment of PRAAD due to transverse ligament laxity in patients with RA.