The repositioning of an autologous bone flap after decompressive craniectomy (DC) for traumatic intracranial hypertension remains the first-line treatment for cranial reconstruction. Aseptic autologous bone flap resorption (BFR) is the most frequent complication. The identification of possible predictive parameters for BFR would help to improve the management of these patients.
Three hundred and nine patients undergoing autologous bone flap repositioning after previous DC for TBI between September 2003 and September 2017 were included in the study.
BFR was identified in 76 (24,59 %) of the 309 patients undergoing autologous CP. Age of ≤ 45 years and CP bone fragmentation were seen to be significant independent risk factors for BFR (p =  0.001 and p =  0.018, respectively) using multivariate logistic regression analysis. Of the radiologic predictors, CP size and the gap between CP and the skull defect were independently associated with BFR (p =  0.034 and p =  0.0003, respectively). The Youden index and ROC curve analysis were used to estimate the cut-off values for the continuous parameters and determine the sensitivity and specificity of the radiologic risk factors. The cut-off value for these two factors was found to be 114,98 cm2 and ≥ 578,5 mm2, respectively. The area under the ROC curve was 0.627 for bone flap size and 0.758 for the DC-CP gap. The DC-CP gap had greater sensitivity and specificity as a predictor of BFR, compared to bone flap size (p = 0.079 and p = ≤ 0.001, respectively).
In this large cohort of patients with autologous cranioplasty, younger age, fragmented autologous bone flap and a wide gap between CP and cranial defect were predictive of bone flap resorption.

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