Risk score for early prognostication of aseptic bone flap necrosis

Abstract

Purpose: Aseptic bone flap necrosis (ABFN) is a common complication of autologous cranioplasty that often requires reoperation. This study aimed to create a risk score for ABFN using relevant demographic, clinical, and laboratory markers.

Methods: We included all patients who underwent autologous cranioplasty after decompressive surgery between 2007 and 2019. We collected laboratory data, initial clinical diagnoses, and demographic parameters before autologous bone flap reimplantation. The significant predictors of ABFN identified in the final multivariate analysis were used to develop a risk score.

Results: Of the 412 patients who underwent craniectomy, 58 (14%, 32 females: 55.2%) developed ABFN. The following independent predictors of ABFN were included in the risk score (0-7 points): craniectomy due to trauma or hemorrhagic stroke (2 points), younger age (< 40 years, 2 points), cranioplasty timing (> 95 days post-craniectomy, 1 point), glutamate-pyruvate transferase < 18 U/L (1 point), and serum creatinine level < 0.815 mg/dL (1 point). The ABFN rates in patients with scores of 0-2, 3-4, and 5-7 points were 4.2%, 16.1%, and 34.6%, respectively. The risk score demonstrated moderate diagnostic accuracy for predicting ABFN, with an area under the curve of 0.739.

Conclusion: The proposed risk score may help in early identification of individuals prone to ABFN. These data suggest that future studies should investigate the significance of metabolic syndromes related to ABFN occurrence. Understanding the potential impact of metabolic factors on ABFN can enhance risk assessment and targeted preventive measures for patients undergoing cranioplasty procedures.

Keywords: Aseptic bone flap necrosis; Biomarker; Bone flap reimplantation; Bone flap resorption; Decompressive hemicraniectomy; Metabolic bone disease.

Fig. 1

Computed tomography of aseptic bone flap necrosis (ABFN). Example case of aseptic bone flap necrosis; 3D reconstruction. Observed in a 51-year-old man who had undergone a right-sided hemicraniectomy due to an acute subdural hematoma and subsequent reimplantation of an autologous bone flap

Fig. 2

ROC curve (receiver operating characteristic) for the aseptic bone flap resorption score. Area under the curve: 0.739 (standard deviation: 0.36; asymptotic 95% confidence interval: 0.648–0.787)

Fig. 3

Distribution of the number of cases that were included in the risk score. All cases were included in the score after multivariate logistic regression analysis. The percentage of ABFN increased with higher scores (the y-axis is logarithmically shown)