Aseptic Bone Flap Resorption after Cranioplasty with Autologous Bone: Incidence, Risk Factors, and Clinical Implications

Objectives: Aseptic bone flap resorption (ABFR) is a known complication of cranioplasty (CP) with an autologous bone flap. The incidence of ABFR has been reported to be as high as 34.2% in the literature; however, it is underestimated in clinical fields. We retrospectively reviewed 13 years of clinical cases of patients who underwent CP after decompressive craniectomy (DC) to investigate the incidence and risk factors of ABFR. Methods: Ninety-one patients who underwent DC and CP in Guro Hospital, Korea University Medical Center, were enrolled. ABFR was defined using serial brain computed tomography. To identify possible risk factors for ABFR, univariate and multivariate Cox regression and receiver operating characteristic curve analyses were performed. Results: Of the 91 patients enrolled, ABFR was diagnosed in 32 patients (35.1%). Bone flap size, existence of a shunting system, and the DC-CP interval were significant in the univariate analysis. Bone flap size was statistically significant in the multivariate analysis (P = 0.0189). The cutoff points of the DC-CP interval and bone flap size were 44 days and 110 cm², respectively. Conclusions: The incidence of ABFR was remarkably high. Bone flap size, the existence of a shunting system, and the DC-CP interval were shown to be potential risk factors of ABFR after CP.