Background: Modifications of the pi craniectomy technique are meant to address the occipital bullet deformity of sagittal synostosis, but it is not clear whether they result in persistent improvement. The authors' purpose was to use morphometric analysis to determine whether a low occipital osteotomy with verticalization results in improved occipital shape after a modified pi procedure 2 years after surgery.
Method: The authors performed a retrospective cohort study comparing modified pi technique with and without a low occipital osteotomy with verticalization immediately and 2 years after surgery relative to age-matched normal controls. The authors used anthropometric measures and population-level anatomical templates using the multivariate template construction script from advanced normalization tools for comparison between groups. A subgroup analysis was performed for severe occipital bullet deformity at presentation.
Results: The authors observed stable improvement in the angle of the inferior occiput with the occipital remodeling modification that persisted 2 years after surgery. This improvement was seen in the entire cohort and was greater in the severe subgroup analysis. Complications and blood transfusion volumes were not different between the 2 techniques. The low occipital osteotomy group demonstrated improved posterior vertical height and cephalic index immediately after surgery, but these did not persist 2 years later.
Conclusions: Occipital remodeling improves the bullet deformity but does not affect posterior vertical height 2 years after surgery. The authors recommend direct inferior occipital remodeling when using the pi technique for young patients with acute occipital incline angles and occipital constriction.
Clinical question/level of evidence: Therapeutic, III.
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