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  • Occipitocervical and Atlantoaxial Fusions of the Pediatric Spine: A Review of Outcomes at a Single Institution

    Final Number:

    Priscilla S Pang MD, MS; Christina M. Sayama MD, MPH; Lissa Catherine Baird MD; Nathan R. Selden MD, PhD

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: The purpose of this study is to determine the fusion rate in posterior instrumented fusions of the craniocervical junction in a pediatric population. Older studies have reported a 98-100% fusion rate on flexion extension x-rays, however more recent studies have demonstrated much lower than anticipated fusion rates from 84-89% on computed tomography (CT). We now report our fusion rates with a minimum of 3 month radiographic follow-up.

    Methods: A retrospective review of 21 consecutive pediatric patients (25 procedures) who underwent posterior occipitocervical or atlantoaxial instrumented fusion from April 2004 to January 2015 at Doernbecher Children’s Hospital was performed. 5 patients were excluded from further analysis because of insufficient follow-up data. Fusion was defined as no motion noted on post-operative flexion-extension x-rays (XR) obtained any time after 3 months. Other factors, such as patient age, body mass index (BMI), diagnosis, number of vertebral levels fused, graft material, and use of postoperative orthosis, were recorded. Half of the patients underwent CT scans as well and thus XR and CT were compared in this cohort.

    Results: 16 patients (20 procedures) had postoperative flexion and extension x-rays obtained at least 3 months after surgery. The average patient age was 10 years, 3 months (range: 2 years, 6 months to 17 years). The mean radiographic follow-up per procedure was 17 months (range: 3 – 118 months; median 8.5 months). Radiographic fusion was achieved in 81% of patients. 4 revision procedures were required in 3 patients (19%). CT-confirmed rates of fusion were even lower; 11 patients with X-ray documented fusion also underwent CT and only 7 of the 11 (64%) had documented CT fusion (grade 4- or 4) .

    Conclusions: Our outcomes of spinal fusion in the pediatric population suggest that rates of fusion in occipitocervical and atlantoaxial instrumented fusions are lower than predicted compared to historical studies and on par with more current studies. Flexion extension x-rays as a means to evaluate fusion may overcall the true bony fusion rate, as depicted by lower fusion rates on CT in those with no instability on x-ray.

    Patient Care: This research will improve patient care by helping to elucidate current problems that may lead to lower fusion rates in OC and C1-C2 fusions in children and to help identify possible ways to improve fusion rates in the future

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of recognizing higher fusion failure rates in OC and C1-C2 fusions of the pediatric spine, 2) Discuss in small groups the possible reasons why fusion rates are so much lower than expected, 3) Identify risk factors for lower fusion rates and ways to increase fusion rates

    References: - Czitrom AA: Biology of bone grafting and principles of bone banking, in Weinstein SL (ed): The Pediatric Spine: Principles and Practice, ed 1. New York: Raven Press, 1994, pp 1285–1298 - Glassman SD, Dimar JR, Carreon LY, Campbell MJ, Puno RM, Johnson JR: Initial fusion rates with recombinant human bone morphogenetic protein-2/compression resistant matrix and a hydroxyapatite and tricalcium phosphate/collagen carrier in posterolateral spine fusion. Spine (Phila Pa 1976) 30:1694–1698, 2005 - Lu DC, Sun PP: Bone morphogenetic protein for salvage fusion in an infant with Down syndrome and craniovertebral instability. Case report. J Neurosurg 106 (6 Suppl):480–483, 2007 - Fahim DK, Whitehead WE, Curry DJ, Dauser RC, Luerssen TG, Jea A: Routine use of recombinant human bone morphogenetic protein-2 in posterior fusions of the pediatric spine: safety profile and efficacy in the early postoperative period. Neurosurgery 67:1195–1204, 2010 - Hwang SW, Gressot LV, Rangel-Castilla L, Whitehead WE, Curry DJ, Bollo RJ, et al: Outcomes of instrumented fusion in the pediatric cervical spine. J Neurosurg Spine 17:397–409, 2012 - Menezes AH: Craniocervical fusions in children. A review. J Neurosurg Pediatr 9:573-585, 2012. - Hankinson TC, Avellino AM, Harter D, Jea A, Lew S, Pincus D, et al: Equivalence of fusion rates after rigid internal fixation of the occiput to C2 with or without C1 instrumentation. Clinical article. J Neurosurg Pediatr 5:380-384, 2010. - Mazur MD, Sivakumar W, Riva-Cambrin J, Jones J, Brockmeyer DL: Avoiding early complications and reoperation during occipitocervical fusion in pediatric patients. J Neurosurg Pediatr 14(5):465-75, 2014.

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