Posterior fixation and fusion for atlantoaxial instability caused by rheumatoid arthritis

English Keywords:Rheumatoid arthritis  Atlantoaxial subluxation  Atlantoaxial fixation  Occipital cervical fusion

English Abstract:

  【Abstract】 Objectives: To assessed the effect of fixation and fusion segment on clinical effects for atlanto-axial instability caused by rheumatoid arthritisand. Methods: 24 patients diagnosed as atlantoaxial instability in RA and operated in Southwest Medical University during January 2005 to March 2015 were reviewed, including 15 males and 9 females, with an average age of 50.8±4.3 years. 21 patents were diagnosed as RA prior to hospitalization with course of disease 2-30 years, 3 patients were diagnosed after admission. Among them, 13 patients were atlantoaxial dislocation(AAS) in lateral X ray, 5 patients were vertical dislocation(VS), 2 patients had both AAS and VS, 1 patient had both AAS and subaxial subluxation(SAS), 1 patient had wire breaking after 3 years of posterior fixation with SAS, 2 patients showed destruction of atlantoaxial joint without any dislocation. All patients underwent posterior fixation and fusion surgery, including atlanto-axial fixation and fusion in 10 cases, C1-3 fixation and fusion in 2 cases due to abnormality of C2 vertebra, occipitocervical fusion in 1 case due to abnormality of C1 vertebra and severe osteoporosis. 7 cases with VS/AAS+VS and 2 cases with severe neck pain underwent occipitocervical/thoracic fusion, including 1 case underwent revision surgery. The Ranawat grade, visual analogue scale(VAS), Japanese Orthopaedic Association(JOA) score were assessed preoperatively, postoperatively and at the final follow-up. Results: All the 24 cases were operated successfully, 2 cases encountered superficial incision infection which cured by changing the dressing and anti-infective therapy. All patients had completed follow-ups of 12-45 months(average, 24.1±10.3 months). VAS score was decreased from the average 6.6±1.2 preoperatively to the average 2.6±0.9 postoperatively, and to 1.8±0.7 at final follow-up(P＜0.05); JOA score was increased from the average 11.5±1.9 preoperatively to the average 13.6±2.0 postoperatively, and to 14.5±1.1 at final follow-up(P＜0.05); Ranawat grade showed that 3 cases with Ranawat class Ⅰ preoperatively remainned class Ⅰ postoperatively, 5 cases with Ranawat class Ⅱ improved to class Ⅰ in 4 cases and remainned class Ⅱ in 1 case, 15 cases with Ranawat class Ⅲa improved to class Ⅰ in 13 cases and class Ⅱ in 2 cases; 1 case with Ranawat class Ⅲb improved to Ⅲa. The fusion rate was 29%(7 patients) in 3 months after operation, and 79%(19 patients) in 6 months after operation, and 100%(24 patients) at final follow-up. 3 patients occurred SAS postoperatively, including 2 patients at C3/4, 1 patient at C4/5. Conclusions: Satisfactory surgical outcomes are achieved by posterior fixation and fusion for atlantoaxial instability caused by rheumatoid arthritis. The segment of posterior fixation and fusion should be chose according to the scope of lesions, dislocation type, bone mineral density and screw pathway condition.