Skull osteology as it affects halo pin placement in children.

Skull bone thicknesses of 18 pediatric skulls were measured by means of computerized tomography scans to determine optimal sites for placement of halo pins. Skulls were grouped to assess changes with age: Group 1, 1-2 years; Group 2, 2-5 years; and Group 3, 5-12 years. At the antero- and posterolateral portions of the calvaria, the average total thickness was 3.7 and 3.9 mm, respectively, in Group 1; this value increased relatively linearly to 6.1 and 5.9 mm, respectively, in Group 3. At the temporal fossa, the average thickness increased from 3.0 mm in infants to 4.1 mm in preteenagers. These findings confirm clinical recommendations that halo fixation pins should be placed anterolaterally and posterolaterally where the bones are thickest.