In situ bioprinting for cartilage repair using a parallel manipulator

Regeneration of large-sized cartilage injury is a challenging endeavor. In vitro bioprinting for cartilage repair has several drawbacks, such as the tedious process of material preparation, potential contamination, and the mismatch between implant and defect. This study aimed to investigate the application of in situ bioprinting in cartilage repair using a parallel manipulator. In particular, the material extrusion rate and printing speed were adjusted to obtain the suitable forming parameters in a custom-made parallel manipulator. Cell experiments were conducted to determine the biocompatibility. Finally, a rabbit cartilage defect model was used to evaluate the feasibility of in situ bioprinting combined with machine vision. The results showed that to achieve optimum printing using the custom-made three-dimensional printer, 400-560 mm/min should be set as the standard printing speed, with an extrusion multiplier of 0.09-0.10. Cartilage defects can be precisely and easily segmented using a bimodal method with a 2% deviation error. In vitro experiments revealed that the utilized materials are highly biocompatible. Furthermore, according to the results from in vivo experiments, in situ bioprinting lends itself useful in the repair of cartilage defects. The overall results confirmed the feasibility of applying a parallel manipulator in in situ bioprinting for cartilage repair. Additional optimizations of the proposed approach are warranted prior to translation into clinical applications in the future.