Introduction: The restitution of large cranial defects with bone is a major clinical challenge. Current implants (bone grafts and inert, alloplastic materials) provide a protection of the brain but suffer from resorption, exposure, infection and ultimately implant removal. The triad of stem cells, biochemical signals and scaffold has shown promising results in experimental models but has not yet been explored in human cranial defects. Novel implants are needed which provide both adequate mechanical support and chemical and microarchitectural cues conducive for bone formation.
Methods: The possibilities to integrate customized 3D-printed/3D-moulded titanium/bioceramic inlay implants in cranial defects were evaluated in altogether 41 patients receiving 43 implants. In the neurosurgical cohort 63% (27/41) of the patients had a history of single or multiple implant explantation (autologous bone, PEEK, PMMA or titanium). The histological analysis of a retrieved human specimen was used to assess the morphology of the regenerated tissue in the defect.
Results: The mean follow-up time was 2 years. The explantation rate because of infection or wound dehiscence was 4.7% (2/43) using the bioceramic implant. Early wound dehiscence with implant exposure occurred in two elderly females attributed to fragile skin quality. Both patients underwent wound revisions that healed without the need of implant removal. One patient required surgery at the site of previous reconstruction and implant removal because of tumor re-growth, which gave the chance of implant retrieval and histological analysis. In retrieved human specimen, the bioceramic was partly transformed into new, well-vascularised osteonal bone.
Conclusions: The clinical data and human retrieval investigation demonstrate proof-of-principle that cranial defects can be mechanically protected and biologically restituted with bone without the supplementation of cells and growth factors.
Patient Care: Cranioplasty is a challenging procedure associated with high complication rate. The use of bone regenerative implants may help to reduce morbidity in treated patients and with lower costs for the health care system.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Identify potential risk factors for implant failure in cranioplasty, 2) Classify and compare different implant techniques and materials used, 3) Recognize possible bone regenerative approaches for cranial repair.
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