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

Abstract

BackgroundBone flap resorption is a known complication of post-decompressive autologous cranioplasty. Although several potential etiopathogenetic factors have been investigated, their role is still under discussion. To further complicate things, resorption is not an all-or-nothing 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 re-surgery before the development of adverse events. MethodsIn a 10-years-time, 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. ResultsAn overall 14.6% incidence of advanced bone resorption was found in our series. Younger age, bone multifragmentation, higher post-cranioplasty GOS scores, < 2 cm distance of medial craniectomy 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 confirmed as risk factors at multivariate analysis. FIS well discriminated the 3 different groups. ConclusionsAutologous 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.