Effectiveness of 3D Printed Polycaprolactone and Tricalcium Phosphate Bone Scaffold for Bone Regeneration in Cranioplasty: Randomized Clinical Trial

The study will be a parallel-arm clinical trial (8 patients randomly divided into 2 groups), where the participants will be patients with cranial defects requiring cranioplasty at the Department of Neurosurgery of Base Hospital of Valdivia, Chile. Previously, data of each participant will be collected, such as sex, age, basic comorbidities and clinical diagnosis.

The outcome variables to be considered in this study are: The volume of bone reconstruction measure in axial computed tomography (CT) using the tool available in Mimics software delivering the value in cm3 , and the scaffold attachment to adjacent bone using the linear density scale in Hounsfield units (HU) where it will be considered from +3000 HU as dense bone formation and presence of GAP <1mm. The last variable will be the patients' perception of esthetics and quality of life, which will be measured using the "QOLIBRI" scale, where the items with the greatest difference in scores between the two groups will be highlighted; in addition, >80 total points will be considered as good quality of life.

Sample calculation: Considering the need to observe the maintenance of skull volume in functional and aesthetic aspects, according to the results of Park et al., the use of PCL/ß-TCP material observed a volume difference of 4.4 ± 2.5% at six months postoperatively versus the average initial volume, calculating the need for four study subjects per group (Effect size d= 1. 76; alpha error probability= 0.05; Power= 0.7; Allocation ratio N2/N1= 1. G*Power software U. Düsseldorf) An experimental group (PCL scaffold + β-TCP) and a control group (PMMA cement).

Surgical intervention PCL + β-TCP intervention protocol: Prior to surgery, the patient must answer a survey of concept of quality of life through the QOLIBRI guideline, followed by this the patient will undergo an initial CT scan where the necessary measurements of the bone defect will be performed to transfer this information to a graphic design software such as CAD 3D, the design and printing of the PCL + β-TCP segment will be performed in the Polymer Laboratory of the Universidad Austral de Chile, once obtained the digital files will be converted to a printable format (.gcode) compatible with fused deposition 3D equipment (FDM), using the Creality Ender-3 printer with PCL filament from Canada Filament Store with a diameter of 1.75 mm.

Subsequently, the prototype will be obtained where it will be verified that the graft has the required characteristics for each patient. Once this is approved, the sterilization protocol of the PCL+ß-TCP matrices will be carried out, which will be placed in a container with 70% ethanol and submerged for 15 minutes, after which time they will be placed on sterile absorbent paper to eliminate excesses. Finally, the scaffolds are exposed to UV light for 20 minutes. Finally, the matrices are packed. Then the surgery will be performed and a control CT scan will be taken 6 months after the intervention, together with the second QOLIBRI guideline.