Meta-Analysis and Meta-Regression of Complications and Failures of Autologous Heterotopic Cranial Bone versus Alloplastic Cranioplasties

Background: Fresh autologous cranial bone graft has been traditionally regarded as the ideal cranioplasty material, however long-term comparisons of outcomes with modern alloplastic materials are absent in the literature. In this work, we evaluated complications and failures among cranioplasties performed with fresh, heterotopic, cranial bone graft versus three common alloplastic materials. Methods: Random-effects meta-analyses of logit-transformed proportions were performed on studies published between 1971-2021 to evaluate complications and failures of cranioplasties performed with fresh, autologous, heterotopic cranial bone, polyetheretherketone (PEEK), polymethylmethacrylate (PMMA), or titanium with a mean follow-up ≥12 months. Generalized mixed model meta-regressions were performed to account for heterogeneity and to evaluate the contributions of moderators to outcomes variables. Results: 1490 patients (mean age 33.9±10.8 years) were included. Pooled, all-cause complications were 6.2% for fresh, heterotopic, autologous cranial bone (95% confidence interval [CI]:2.1-17.0%; I 2 =55.0%, p =0.02), 18.5% for PEEK (95%CI:14.0-24.0%; I 2 =0.0%, p =0.58), 26.1% for titanium (95%CI:18.7-35.1%; I 2 =60.6%, p <0.01), and 28.4% for PMMA (95%CI:12.9-51.5%; I 2 =88.5%, p <0.01). Pooled all-cause failures were 2.2% for fresh, autologous cranial bone (95%CI:0.4-10.6%; I 2 =0.0%, p =0.45), 6.3% for PEEK (95%CI:3.2-12.3%; I 2 =15.5%, p =0.31), 11.4% for titanium (95%CI:6.7-18.8%; I 2 =60.8%, p <0.01), and 12.7% for PMMA (95%CI:6.9-22.0%; I 2 =64.8%, p <0.01). Meta-regression models indicated that each alloplastic subtype significantly and independently predicted higher complications, while titanium and PMMA were significant predictors for all-cause failures compared to autologous bone. All three subtypes were predictive of higher cranioplasty failures secondary to infection compared to autologous bone. Conclusions: Cranioplasties performed with fresh, autologous heterotopic cranial bone grafts resulted in lower complications and failures compared to alloplastic materials.