Evidence of Linear Bone Flap Resorption in Patients Undergoing Autologous Cranioplasty Following Decompressive Craniectomy: A 3D Slicer Segmented Analysis of Serial Computed Tomography Images

Abstract

Autologous cranioplasty (CP) following decompressive craniectomy (DC) carries a risk of bone flap resorption (BFR). The current literature offers limited information regarding the natural progression of BFR and the rate at which it occurs. We aim to characterize the progression of BFR over time and elucidate risk factors for accelerated BFR. A retrospective analysis was conducted on patients who underwent DC and autologous CP. Serial computed tomography (CT) images were used to quantify the degree of BFR over time. Risk factors included age, diabetes, smoking status, flap fragmentation, defect size, and DC-CP time interval. χ2 analyses and Student's t-tests were performed to examine differences between patients who experienced BFR and those who did not. Overall, 82% of patients demonstrated evidence of clinically relevant resorption on CT. On average, the bone flap decreased in volume by 36.7% within the first year, with a linear loss in volume after multiple years of follow-up. Individuals who developed greater BFR were significantly younger (43±17 vs. 56±12, P= 0.022), had a lower incidence of diabetes (5.9% vs. 43%, P= 0.037), and had more bone flap fragments (1.4±0.67 vs. 1.00±0, P<0.001) than those who did not. Resorption following CP with cryopreserved bone appears to progress in a fairly linear and continuous fashion over time. Using serial CT images, we found a resorption rate of 82% at our institution. We identified several possible risk factors for resorption, including flap fragmentation, younger age, and absence of diabetes.