Retrospective Chronologic Computed Tomography Analysis of Bone Flap Fusion and Resorption After Craniotomy and Autologous Cryopreserved Cranioplasty

Abstract

In open brain surgery, fixation of the bone flap is the final procedure. The bone flaps then fuse naturally. The objective of this study was to investigate the chronological process of bone fusion after craniotomy and autologous cranioplasty. Retrospective data were collected from patients who underwent craniotomy or cranioplasty after August 2004 and had at least 1 computed tomography (CT) scan at 3 months postsurgery. The patients were divided into a craniotomy group and a cranioplasty group. Head CT scans were analyzed to evaluate bone fusion and resorption. Records from 978 patients who underwent craniotomy or cranioplasty between September 2004 and November 2015 were reviewed; 369 patients were eligible for the final analysis (craniotomy, n= 276; cranioplasty, n= 93). The mean cryopreservation period for the bone flap in the cranioplasty group was 49.3 days. The mean patient age was 51.4 ± 18.1 years in the craniotomy group and 51.6 ± 17.1 years in the cranioplasty group. Head CT scans showed bone fusion rates of 76.6% in the craniotomy group and 53.3% in the cranioplasty group at 6 months postsurgery (P= 0.015) and 78.6% and 78.1%, respectively, at 1 year postsurgery (P= 0.951). There was also a significant difference in the bone flap resorption rate between the 2 groups. Bone flap fusion rates after craniotomy and cranioplasty were significantly different before 12 months, but not significantly different thereafter. Bone resorption occurred more frequently in the cranioplasty group over time.