Comprehensive functional outcome analysis and importance of bone remodelling on personalized cranioplasty treatment using Poly(methyl methacrylate) bone flaps

Cranioplasty involves the surgical reconstruction of cranial defects arising as a result of various factors, including decompressive craniectomy, cranial malformations, and brain injury due to road traffic accidents. Most of the modern decompressive craniectomies (DC) warrant a future cranioplasty surgery within 6–36 months. The conventional process of capturing the defect impression and polymethyl methacrylate (PMMA) flap fabrication results in a misfit or misalignment at the site of implantation. Equally, the intra-operative graft preparation is arduous and can result in a longer surgical time, which may compromise the functional and aesthetic outcomes. As part of a multicentric pilot clinical study, we recently conducted a cohort study on ten human subjects during 2019–2022, following the human ethics committee approvals from the participating institutes. In the current study, an important aspect of measuring the extent of bone remodelling during the time gap between decompressive craniectomy and cranioplasty was successfully evaluated. The sterilised PMMA bone flaps were implanted at the defect area during the cranioplasty surgery using titanium mini plates and screws. The mean surgery time was 90 ± 20 min, comparable to the other clinical studies on cranioplasty. No signs of intra-operative and post-operative complications, such as cerebrospinal fluid leakage, hematoma, or local and systemic infection, were clinically recorded. Importantly, aesthetic outcomes were excellent for all the patients, except in a few clinical cases, wherein the PMMA bone flap was to be carefully customized due to the remodelling of the native skull bone. The extent of physiological remodelling was evaluated by superimposing the pre-operative and post-operative CT scan data after converting the defect morphology into a 3D model. This study further establishes the safety and efficacy of a technologically better approach to fabricate patient-specific acrylic bone flaps with improved surgical outcomes. More importantly, the study outcome further demonstrates the strategy to address bone remodelling during the patient-specific implant design.