Intraarticular cortical bone graft implantation combined with lateral mass-pedicle screw rod fixation for irreducible atlantoaxial dislocation

English Keywords:Irreducible atlantoaxial dislocation  Craniovertebral junction malformation  Lateral mass-pedicle screw rod fixation  Upper cervical fixation  Intraarticular bone graft implantation

English Abstract:

  【Abstract】 Objectives: To introduce the technique of intraarticular cortical bone graft implantation combined with lateral mass-pedicle screw rod fixation(Goel technique) for irreducible atlantoaxial dislocation, and to evaluate the reduction of dislocation and the reversion of clivus-canal angle. Methods: The study retrospectively reviewed 16 cases with irreducible atlantoaxial dislocation from June 2015 to June 2016(intraarticular pedestal group), who were treated with intraarticular cortical bone graft implantation combined with Goel technique. Fifteen cases up to the same inclusion criteria in the same period who were treated by single Goel technique, were recruited as the control group(control group). The JOA scores, the atlanto-dental distance(ADI), the value of basilar invagination(BI), and the clivus-canal angle(CCA) before and after operation were compared between the two groups to evaluate the clinical results. Results: There was no statistically significant difference in age, sex ratio, mean follow-up time, preoperative JOA score, ADI, BI, or CCA. The two groups were comparable. In the intra-articular pedestal group, the cortical bone grafts were implanted bilaterally in 14 cases. In the other 2 cases(with unilateral dislocation), the bone grafts were only implanted in dislocation side. One case in the intraarticular pedestal group occurred bone graft subsidence into articular process. There was no operative complication in the remaining cases of two groups. In intraarticular pedestal group, the postoperative JOA, ADI and BI value were 15.2±1.1, 2.4±1.5mm and 5.8±3.9mm respectively. In control group, the postoperative JOA, ADI and BI value were 14.7±1.6, 2.9±2.7mm and 5.7±2.6mm respectively. There was no statistically significant difference of the values between two groups(P>0.05). The CCA reversed from 123.1°±16.3° to 148.1°±11.2° after operation in intraarticular pedestal group. In control group, the CCA changed from 125.6°±14.2° to 116.6°±10.5° postoperatively. There was a statistically significant difference of postoperative CCA between two groups(P=0.000). No broken of screw/rod, loosen of internal fixation, or loss of reduction was reported in follow-up. All patients had exhibited solid bony fusion between occipital and neck. Conclusions: The intraarticular cortical bone graft implantation technique can be used to assist Goel technique to effectively and safely reduce the atlantoaxial dislocation. The preliminary results show that this technique is helpful for the treatment of irreducible atlantoaxial dislocation and can improve(enlarge) the clivus-canal angle after-operation.