Use of allograft bone for posterior C1–2 fusion

OBJECT: An iliac crest autograft is the gold standard for bone grafting in posterior atlantoaxial arthrodesis but can be associated with significant donor-site morbidity. Conversely, an allograft has historically performed suboptimally for atlantoaxial arthrodesis as an onlay graft. The authors have modified a bone grafting technique to allow placement of a bicortical iliac crest allograft in an interpositional manner, and they evaluated it as an alternative to an autograft in posterior atlantoaxial arthrodesis. METHODS: The records of 89 consecutive patients in whom C1-2 arthrodesis was performed between 2001 and 2005 were reviewed. RESULTS: Forty-seven patients underwent 48 atlantoaxial arthrodeses with an allograft (mean follow-up 16.1 months, range 0-49 months), and 42 patients underwent autograft bone grafting (mean follow-up 17.6 months, range 0-61.0 months). The operative time was 50 minutes shorter in the allograft (mean 184 minutes, range 106-328 minutes) than in the autograft procedure (mean 234 minutes, range 154-358 minutes), and the estimated blood loss was 50% lower in the allograft group than in the autograft group (mean 103 ml [range 30-200 ml] vs mean 206 ml [range 50-400 ml], respectively). Bone incorporation was initially slower in the allograft than in the autograft group but equalized by 12 months postprocedure. The respective fusion rates after 24 months were 96.7 and 88.9% for autografts and allografts. Complications at the donor site occurred in 16.7% of the autograft patients, including 1 pelvic fracture, 1 retained sponge, 1 infection, 2 hernias requiring repair, 2 hematomas, and persistent pain. CONCLUSIONS: The authors describe a technique for interpositional bone grafting between C-1 and C-2 that allows for the use of an allograft with excellent fusion results. This technique reduced the operative time and blood loss and eliminated donor-site morbidity.