The timing of cranioplasty and the risk of postoperative complications: a systematic review and meta-analysis

Background: The ideal timeframe for performing cranioplasty (CP) following decompressive craniectomy (DC) remains to be conclusively determined. We aimed to investigate the association between timing of CP and the risk of postoperative complications after CP. Insight into the association between them will guide timing of CP to improve the outcome of patients. Methods: Pubmed, Embase, the Cochrane Library, Web of Science, and Scopus were searched from January 1st, 1990 to June 30th, 2025. Studies reporting the association between the timing of CP and the risk of postoperative complications, and the rate of participants with complications for each DC-CP time interval (≤1 month vs. >1 month, ≤1.5 months vs. >1.5 months, ≤2 months vs. >2 months, ≤3 months vs. >3 months, ≤6 months vs. >6 months) were involved. A random-effects model was applied to the meta-analysis. The protocol of this study was registered in PROSPERO (CRD42024558653). Findings: A total of 65 studies were included. The results of the meta-analysis suggested that CP performed within 1 month (vs. CP performed beyond 1 month) after DC was associated with a reduced risk of PCs (OR 0.62, 95% CI 0.35-1.09), although this association was not statistically significant. Compared to CP performed more than 3 months after DC, CP performed within 3 months after DC did not show a significantly reduced or increased risk of overall postoperative complications (OR 1.03, 95% CI 0.80-1.34). However, compared to CP performed beyond 3 months after DC, CP performed within 3 months was associated with an increased risk of postoperative hydrocephalus (OR 1.59, 95% CI 0.97-2.59), although this association did not reach statistical significance. Interpretation: CP performed within 1 month (vs. CP performed beyond 1 month) after DC was probably associated with a reduced risk of overall PCs. CP performed within 3 months (vs. CP performed beyond 3 months) did not show a significantly reduced or increased risk of overall PCs compared to CP performed more than 3 months. While, CP performed within 3 months (vs. CP performed beyond 3 months) was probably associated with an increased risk of postoperative hydrocephalus. Funding: President Foundation of ZhuJiang Hospital, Southern Medical University (yzjj2023qn26), Science and Technology Program of Guangzhou (No. 2024A04J4801), Basic Research of Shenzhen Natural Science Foundation (Surface Project, No. JCYJ20210324114008023), and the National Natural Science Foundation of China (No. 82403092).