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  • Pediatric Occipital Condyle Morphometric Analysis Using Computed Tomography with Evaluation for Occipital Condyle Screw Placement

    Final Number:

    Khoi Dinh Nguyen MD; Angela Viers MD; Jonathan Allen Tuttle MD; Ian M. Heger MD, FAAP, FACS

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2018 Annual Meeting

    Introduction: Occipitocervical fusions in the pediatric population are rare, but can be challenging due to smaller anatomy. The procedure is even more challenging in patients with prior suboccipital craniectomy. A proposed method for occipitocervical fusion in these challenging patients is the use of occipital condyle screws. There is very limited literature on evaluating the pediatric occipital condyle for screw placement. Our institution seeks to determine if there is an age cutoff where condylar screw placement would be contraindicated.

    Methods: A retrospective morphometric analysis of pediatric occipital condyles was performed using computed tomography (CT) imaging of the head, cervical spine, or CT angiography of the neck. The CT scans of 518 pediatric patients at our institution were evaluated. There were 205 females and 313 males, with ages ranging from 1 week to 9 years. Measurements of occipital condyles and screw trajectory were obtained in the axial,coronal, and sagittal planes (see Figure 1). Descriptive statistical analysis was performed using mean, standard deviation, and confidence intervals for all measurements. Probability values were calculated using Student's t-test. P value less than 0.05 was considered statistical significance.

    Results: Age distribution of all patients analyzed and percentage of patients that did not meet size recommendations for screw placement are summarized in Tables 1 and 2, respectively. Table 3 summarizes the average measurements of condylar length, height, and width, as well as projected screw angle and length. Overall, males had larger occipital condyles compared to females with statistical significance. As expected, there was a general trend toward older children having larger occipital condyles. Overall, 20.65% of all patients were found to have at least one occipital condyle measurement that would prevent screw placement, including at least one patient in every age group.

    Conclusions: Occipital condyle screw fixation is feasible in pediatric patients under 10 years old. All pediatric patients that require craniocervical fusion should undergo critical evaluation of the occipital condyles preoperatively to determine suitability for occipital condyle screw placement.

    Patient Care: This research should help practitioners be more familiar with occipital condyle screw placement in the pediatric population, and help them recognize that the technique is feasible in very young patients.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Be familiar with the technique of occipital condyle screw placement. 2) Realize that the technique is potentially feasible in pediatric patients less than 10 years old.

    References: 1. Bekelis K, Duhaime AC, Missios S, Belden C, Simmons N. Placement of occipital condyle screws for occipitocervical fixation in a pediatric patient with occipitocervical instability after decompression for Chiari malformation. J Neurosurg Pediatr 6:171-176, 2010. 2. Frankel BM, Hanley M, Vandergrift A, Monroe T, Morgan S, Rumboldt Z. Posterior occipitocervical (C0-3) fusion using polyaxial occipital condyle to cervical spine screw and rod fixation: a radiographic and cadaveric analysis. J Neurosurg Spine 12:509-516, 2010. 3. Lin SL, Xia DD, Chen W, Li Y, Shen ZH, Wang XY, et al. Computed tomographic morphometric analysis of the pediatric occipital condyle for occipital condyle screw placement. Spine (Phila Pa 1976) 39:E147-152, 2014. 4. Naderi S, Korman E, Citak G, Guvencer M, Arman C, Senoglu M, et al. Morphometric analysis of human occipital condyle. Clin Neurol Neurosurg 107:191-199, 2005.

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