Autologous Bone Is Inferior to Alloplastic Cranioplasties: Safety of Autograft and Allograft Materials for Cranioplasties, a Systematic Review

BACKGROUND: Currently, various materials are routinely used for cranioplasty after decompressive craniectomy, each with their own features, potential benefits, and harms. OBJECTIVES: To systematically review available literature about safety (infection, resorption, and removal) of different materials used for cranioplasty for any indication. METHODS: A comprehensive search in MEDLINE, EMBASE, and the Cochrane library was performed for relevant studies published up to January 2017. Study quality was assessed according to the Cochrane Collaboration risk of bias assessment tool, and a set of 27 predetermined parameters was extracted by 2 investigators independently for further analysis. RESULTS: The search yielded 2 randomized, 14 prospective, and 212 retrospective studies, totaling 10,346 cranioplasties in which 1952 (18.9%) complications were reported in patients between 0 and 90 years old. Overall, study quality was low and heterogeneity was large. Graft infections and resorption were most prevalent: overall infection rate was 5.6%. Autologous cranioplasties showed an infection rate of 6.9% versus 5.0% in combined alloplastic materials, including poly(methyl methacrylate) with 7.8%. Resorption occurred almost exclusively in autologous cranioplasties (11.3%). The greatest removal rate was reported for autologous cranioplasties (overall: 10.4%), which was significantly greater than that of combined alloplastic materials (overall: 5.1%; risk difference [0.052 [95% confidence interval: 0.039-0.066]; NNT = 19 [95% confidence interval: 15-25]). CONCLUSIONS: Available evidence on the safety of cranioplasty materials is limited due to a large diversity in study conduct, patients included, and outcomes reported. Autografts appear to carry a greater failure risk than allografts. Future publications concerning cranioplasties will benefit by a standardized reporting of surgical procedures, outcomes, and graft materials used.