Introduction: Occipitocervical fusion of the pediatric spine has traditionally been accomplished by the use of cabled grafts and halo fixation. However, rigid internal fixation offers biomechanical advantages and possible increased stability. This study evaluates the feasibility of rigid occipitocervical internal fixation in children 2 to 6 years old.
Methods: 50 head and cervical CT scans in pediatric trauma patients ages 2–6 years old were evaluated for the anatomy of the occiput, C1 lateral mass, C2 pedicle, C2 isthmus, C2 lamina, and a potential C1–2 transarticular path. Two separate spine surgeons assessed the feasibility of occipital cervical fixation in these patients.
Results: C1 lateral mass height/length was adequate for screw fixation (>5mm width) in all 100 lateral masses. C2 pedicle fixation was considered feasible (>4mm width/height) in 49 of 100 C2 pedicles, and difficult but possible (3.5–4.0mm) in 25 C2 pedicles. C2 lamina fixation was considered feasible (>3.5mm) in 99 of 100 C2 laminas. C1–2 transarticular screws were considered difficult but possible (3.5–4.0) in 4 of 100 sides. Either C2 bicortical pedicle or C2 lamina screws could be placed in 99/100 sides. There were age related differences in C2 pedicle height between the 2 and 6 year old patients (p<0.02). Occipital bone was thickest at the external occipital protuberance in all 50 posterior skulls. This was thicker in the 6 year olds (10.5mmSD1.0) than the 2 year olds (8.4mmSD1.2) (p=0.005). Thickness was at least 6 mm in 49 of 50 EOP, and at least 8mm in 42 of 50 EOP. Determination by both surgeons was that an occipital keel plate was feasible and the best fixation option in all 50 skulls.
Conclusion: In this CT feasibility study of 50 pediatric patients age 2–6 years old, occipital fixation with a midline keel plate was possible in all subjects and rigid internal fixation bilaterally at C1 was possible in all, and 49 of 50 could have had internal fixation bilaterally into either the C2 pedicle or the C2 lamina. In this age group, C1–2 transarticular screws were considered contraindicated in 96/100 sides.
Significance: This study demonstrates that internal fixation of the occiput, C1, and C2, is anatomically feasible in children 2–6 years old