Bone Flap Resorption after Cranioplasty: Risk Factors and Proposal of the Flap Integrity Score.

BACKGROUND: Bone flap resorption is a known complication of postdecompressive autologous craniohave been investigated, their role is still under discussion. To further complicate things, resorption is not an all-ornothing event, patients frequently presenting with different degrees of flap remodeling. Focus of this paper was to describe the elaboration of a score quantifying bone resorption according to a set of clinical and radiological criteria, hopefully allowing prompt identification of patients needing resurgery before the development of adverse events. METHODS: In a 10-year period, 281 autologous cranioplasties were performed at our institution following decompressive craniectomy. Pertinent clinical and radiological information was registered. A set of 3 clinical and 3 radiological parameters was established to score the degree of resorption, identified under the acronym FIS (Flap Integrity Score). Three groups of patients emerged, respectively showing no (208), partial (32), and advanced (41) resorption. - RESULTS: An overall 14.6% incidence of advanced bone resorption was found in our series. Younger age, bone Outcome Scale scores, <2 cm distance of medial cra-iectomy border from the midline, and cause leading to decompressive craniectomy were associated to a statistically significant higher risk of developing a relevant bone flap resorption. The first three variables were confirmed as risk factors in multivariate analysis. Flap Integrity Score well discriminated the 3 different groups. CONCLUSIONS: Autologous bone repositioning is still a valuable, low-cost, cosmetically and functionally satisfactory procedure. Nonetheless, although resorption affects a minor percentage of patients, its early identification and treatment can improve long-term results.