Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P98. Does additional bone grafting of atlantoaxial joint increase the bone fusion rate of iliac crest autograft in posterior occipitocervical fusion? A retrospective, controlled study with a two-year follow-up

Abstract

BACKGROUND CONTEXT Occipitocervical fusion can be utilized to correct joint instability caused by trauma, rheumatological conditions, infection, neoplasm, or congenital conditions. Bone-graft-related complication was relatively frequent during occipitocervical fusion surgery. In previous studies, the reported fusion rates were ranged from 83.6% to 100%; and the rate of instrumentation failure after nonunion was as high as 7% during occipitocervical fusion. PURPOSE To explore whether additional bone grafting of atlantoaxial joint increase the bone fusion rate of iliac crest autograft in posterior occipitocervical fusion surgery. STUDY DESIGN/SETTING A retrospective, controlled study with a 2-year follow-up. PATIENT SAMPLE Between January 2014 and January 2016, a total of 48 consecutive patients underwent posterior occipitocervical fusion with a screw-rod fixation system in a tertiary spine center. OUTCOME MEASURES In the postoperatively follow up, patients underwent computed tomography (CT) scan at every interval until bone fusion was confirmed. The related complications were also recorded. METHODS In the control group, we only placed a piece of autogenous iliac corticocancellous bone between the occipital and C2 vertebral laminae for fusion. In the hybrid fusion group, besides posterior occipitocervical autograft, we additionally pack some granular bone harvested from the iliac crest into bilateral atlantoaxial joint. RESULTS Only a piece of autogenous iliac corticocancellous bone was placed between the occipital and C2 in 24 patients to perform posterior occipitocervical fusion. In the other 24 cases, besides posterior occipitocervical autograft, we additionally pack some granular bone harvested from the iliac crest into bilateral atlantoaxial joint. All patients were followed for at least 24 months. Only 21 (87.5%) patients in the control group had confirmed posterior bony fusion on CT imaging while 24 (100%) patients in the hybrid fusion group had confirmed posterior bony fusion. There were postoperative implant-related complications in 2 patients; screw loosening was visible in one case, pullout and breakage of internal fixation was observed in another case. All two cases were belong to the control group (8.3%). Mean duration to posterior occipitocervical fusion was 5.5 months in the hybrid fusion group versus 6.1 months in the control group (P=.037). Of note, in the hybrid fusion group, the process of atlantoaxial joint fusion was faster than that of posterior occipitocervical fusion (5.1 months vs. 5.5 months, p=.103). CONCLUSIONS Additional bone grafting of atlantoaxial joint could increase the bone fusion rate of iliac crest autograft and promote the process of bone fusion in posterior occipitocervical fusion.