title: Complications and outcomes of posterior fusion in children with atlantoaxial instability.
abstract: BACKGROUND
  Atlantoaxial instability (AAI) is an uncommon disease in children. Surgical treatment of pediatric patients with AAI poses a challenge to spine surgeons because of the patients' immature bone quality, extensive anatomical variability, and smaller osseous structures. In this study, the authors report complications and outcomes after posterior fusion in children with AAI.
  
  
  METHODS
  The authors reviewed medical records of patients 13 years old and younger with AAI who underwent posterior fusion in the Nagoya Spine Group hospitals, a multicenter cooperative study group, from January 1995 to December 2007. We identified 11 patients who underwent posterior fusion, and analyzed their clinical outcomes and complications. To determine if vertical growth within the construct continued after posterior fusion, in three patients at 5 or more years following occipito-cervical (O-C) fusion, intervertebral disc heights and vertebral heights between the fused and non-fused levels were compared on the final follow-up.
  
  
  RESULTS
  The initial surgeries were C1-C2 fusions in six patients and O-C fusion in five patients. Successful fusion ultimately occurred in all patients, however, the complication rate related to the operations was high (64%). Complications included neurologic deterioration, pedicle fracture with pedicle screw insertion, C1 posterior arch fracture with lateral mass screw insertion, perforation of the skull with a head pin placement, and fusion extension to adjacent vertebrae. Two patients required reoperation. The mean fixed and non-fixed intervertebral disc heights on the final follow-up were 2.6 and 5.3 mm, respectively, showing that the disc height of the fixed level was less than the non-fused level. Each vertebra lengthened similarly between fused and non-fused levels except for C2 which had a lower growth rate than the other vertebrae.
  
  
  CONCLUSIONS
  A high complication rate should be anticipated after posterior fusion in children with AAI. Careful consideration should be paid to pediatric patients with AAI treated by screw and/or rod systems. After posterior fusion in pediatric patients, each vertebra continued to grow, in contrast the disc height decreased between fused levels.
authors: Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya 4668550, Japan. ryoji-t@med.nagoya-u.ac.jp
authors: Ryoji
authors: R
authors: Tauchi
authors: Shiro
authors: S
authors: Imagama
authors: Zenya
authors: Z
authors: Ito
authors: Kei
authors: K
authors: Ando
authors: Kenichi
authors: K
authors: Hirano
authors: Akio
authors: A
authors: Muramoto
authors: Hiroki
authors: H
authors: Matsui
authors: Fumihiko
authors: F
authors: Kato
authors: Yasutsugu
authors: Y
authors: Yukawa
authors: Koji
authors: K
authors: Sato
authors: Tokumi
authors: T
authors: Kanemura
authors: Hisatake
authors: H
authors: Yoshihara
authors: Mitsuhiro
authors: M
authors: Kamiya
authors: Yukihiro
authors: Y
authors: Matsuyama
authors: Naoki
authors: N
authors: Ishiguro
mesh_terms: D000293:Adolescent; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001858:Bone Nails; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000254:growth & development / Q000293:injuries / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D009422:Nervous System Diseases / Q000453:epidemiology / Q000209:etiology; D009777:Occipital Bone / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D016103:Spinal Fractures / Q000453:epidemiology / Q000209:etiology; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome