ATLANTOAXIAL DISLOCATION - A FOLLOW-UP-STUDY OF SURGICAL RESULTS

Study Design. The cases of 47 patients with atlantoaxial dislocation e xclusive of rheumatoid arthritis, cerebral palsy, and tumors as causat ive pathologies were reviewed after surgical treatment, which was perf ormed between 1979 and 1993. Objectives, To investigate the surgical r esults of atlantoaxial dislocation itself without any systemic factors affected by rheumatoid arthritis, cerebral palsy, and tumors. Methods . Neck pain (or occipitalgia) and extent of myelopathy at follow-up ev aluation were compared with that present before surgery. The results w ere classified into four groups: excellent (no pain or recovery rate i n myelopathy of more than 50%), good (decreased pain or recovery rate of 25% to 50%), fair (no improvement of pain or recovery rate of zero to 25%), and poor (aggravation of pain or recovery rate less than zero ). The average follow-up period was 4 years and 2 months. Results. Of the patients evaluated, 51% were assessed as excellent, 23% as good, 7 % as fair, and 19% as poor. Pain relief was achieved in 95% of patient s with non myelopathy. Extent of myelopathy, pathology of atlantoaxial dislocation (ligamentous or osseous instability), loss of reduction a fter surgery, and surgical procedures were recognized as the major fac tors affecting surgical results. Better surgical results were obtained in mild myelopathy cases (> 10 points in Japan Orthopaedic Associatio n scoring), ligamentous instability, and cases without loss of reducti on. The incidence of pseudarthrosis and loss of reduction was low in B rooks' method for atlantoaxial fusion and in Luque's segmental sublami nal wiring method for occipitocervical fusion. Conclusion. The best re sults occurred in patients with no myelopathy, and the worst results o ccurred in patients with severe myelopathy; therefore, surgery is best indicated for atlantoaxial dislocation with intractable pain or with mild myelopathy. To avoid pseudarthrosis and loss of reduction, a stro ng fixation method, such as Brooks' or Luque's segmental sublaminal wi ring method, should be selected.