In Situ Extrusion of Biomaterials Through an Arthroscopic Tool: Characterization and Numerical Analyses

This study describes a handheld device designed for the controlled extrusion of cell-free and cell-laden biomaterials in an arthroscopic setting. The handheld extruder has a bendable nitinol tip that is manually controlled by the surgeon, that allows reaching different anatomical areas. The system also comprises a supply unit. The tip has a range of motion up to $90°}$. Finite element simulations were used to verify stress distribution on the tip. A rheological characterization of the biomaterials under investigation (VitroGel-RGD, methacrylated gellan gum, alginate-gelatin, Hymovis®, Condrotide®, fibrin glue, and Medigraft®) was performed. Biological tests demonstrated the device's capability to extrude cell-laden biomaterials without compromising cell viability. Computational fluid dynamics simulations were conducted to assess wall shear stress and extrusion force. None of the involved biomaterials exceeded the sefaty threshold of 5 kPa for the wall shear stress. Alginate-gelatin, Condrotide® and Hymovis® exhibited forces exceeding the recommended limits set by ISO standards, suggesting caution in their use with the proposed flow rate. The proposed handheld device resulted a promising solution for an in situ treatment of articular cartilage lesions, guaranteeing a minimally invasive approach coupled with a controlled extrusion of biomaterials.