title: Impact of interlaminar graft materials on the fusion status in atlantoaxial transarticular screw fixation.
abstract: OBJECTIVE
  Structural interlaminar graft materials were used for atlantoaxial transarticular screw fixation (TSF), and its impact on the fusion status was investigated.
  
  
  METHODS
  Forty-two patients (10 men, 32 women, mean age 51 years, mean follow-up period 45 months; 30 with rheumatoid arthritis, and 12 with os odontoideum) underwent TSF and modified Brooks posterior wiring involving titanium cables. As interlaminar graft materials, autologous bone from posterior iliac crest alone was used in 20 patients (Group A), and a structural spacer (13 ceramic spacers, nine titanium mesh cages) in 22 (Group B). Lateral radiographs were evaluated to determine bone fusion, alignment of the cervical spine, and wire loosening. Solid osseous fusion was obtained in 95% of Group A and 96% of Group B patients. The mean atlantoaxial angle was 19.1+/-9.7 degrees and 16.7+/-10.4 degrees before surgery (p = 0.45), and 27.4+/-7.8 degrees and 22.1+/-5.5 degrees after surgery (p = 0.02) in Groups A and B, respectively. Atlantoaxial hyperlordosis (atlantoaxial angle > or = 30 degrees) was observed in 32% of Group A and 18% of Group B patients (p = 0.26). Postoperative kyphosis occurred in 40% of Group A and 23% of Group B patients (p = 0.28). Loosening of the cable was demonstrated in 50% of Group A and 36% of Group B patients(p = 0.37). In Group B patients maintenance of cervical lordosis was more likely than in those in Group A, although the differences did not reach statistical significance.
  
  
  CONCLUSIONS
  These results indicate that structural interlaminar spacers can maintain proper cervical alignment without a decease in the fusion rate; the authors recommend their use in conjunction with TSF.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan. morio@sc.itc.keio.ac.jo
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chiba
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yuto
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Jun
authors.initials: J
authors.lastname: Ogawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000601:surgery; D001268:Atlanto-Axial Joint / Q000601:surgery*; D001672:Biocompatible Materials; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016268:Internal Fixators; D007593:Joint Instability / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care; D013123:Spinal Fusion / Q000295:instrumentation*; D014025:Titanium / Q000627:therapeutic use
chemical_list: D001672:Biocompatible Materials; D014025:Titanium