Could Future Surgical Guides Begin as Plastic Waste? A New Chapter for Hospital 3D Printing

The recycled ABS produced accurate test pieces, supported the printing of complex medical prototypes, and passed the study’s cell-toxicity checks after sterilisation.

A plastic model of a patient's spine can help a surgical team understand anatomy before an operation, giving hospital 3D printing a practical role in personalised care. Producing these models and surgical guides requires materials that deliver precise shapes and meet the safety needs of their intended use. Researchers are exploring whether recycled plastic can meet those demands and reduce dependence on newly manufactured material.

The study, "Closing the loop in healthcare: chemically recycled ABS for 3D printing of medical device," published in Frontiers in Bioengineering and Biotechnology, examines that possibility. Alberto Bevilacqua and colleagues tested chemically recycled acrylonitrile butadiene styrene, commonly called ABS, for printing medical items that are not implanted in the body. Their work followed the material from pellets to printer filament and finished objects, checking dimensional accuracy and its effects on laboratory-grown cells.

The recycled ABS produced accurate test pieces, supported the printing of complex medical prototypes, and passed the study's cell-toxicity checks after sterilisation. Printed samples gave a cell-survival result close to that of a certified medical-grade ABS used for comparison. These findings provide an early foundation for further development, with questions about clinical performance and environmental benefits still requiring investigation.

Giving Recycled Plastic a Route Into Medical Printing

Medical manufacturing needs consistent materials, making the variable composition of recovered plastic a practical concern. Mechanical recycling reshapes existing polymers and can carry forward additives or introduce changes through repeated processing. Chemical recycling breaks plastic waste into molecular feedstocks that can enter conventional production processes to make new polymers.

Versalis supplied the chemically recycled ABS through a certified pathway using feedstocks derived from pyrolysis, a process that breaks down plastic through heat. Its recycled content was assigned through mass-balance accounting, which tracks recycled inputs and allocates a corresponding share to the finished product. This accounting approach does not mean that every portion of the final material contains an individually traceable amount of recycled plastic.

The preliminary chemical screening examined separate mechanically recycled ABS streams from electrical equipment and automotive sources, checking halogens, metals, fillers, residual substances, and additives. The researchers reported no prohibited hazardous substances in those screened streams. They selected chemically recycled ABS for the printing and biological experiments because they expected more consistent material properties and lower contamination risks.

Small Measurements Reveal How Well the Plastic Prints

The team first compared four virgin ABS formulations to establish suitable printing behaviour before transferring the process to a chemically recycled counterpart. Recycled pellets were processed into continuous filament measuring 1.75 millimetres in diameter, then printed in a laboratory certified to ISO 13485 for medical-device quality management. Fused deposition modelling built each object layer by layer, with temperature control helping limit material degradation during processing.

Test cubes designed to measure 25.00 millimetres averaged 24.93 millimetres, with a standard deviation of just 0.02 millimetres indicating closely grouped measurements. A flow-test piece designed with a wall thickness of 1.20 millimetres measured 1.22 millimetres on average, with a standard deviation of 0.01 millimetres. Standardised dog-bone specimens stayed below 1.5% average dimensional deviation across their main measured axes.

Patient-specific anatomical models, surgical cutting guides, vertebral guides, and a medication tray demonstrated the material's ability to form more complex objects. Visual inspection found adequate surfaces without obvious large defects, separation between layers, or severe warping. These prototypes demonstrated manufacturing feasibility, with no patient trial reported to establish surgical outcomes or performance during clinical use.

What Happened When Living Cells Met the Material

The researchers tested raw recycled pellets, extruded filament, and printed cylinders to examine whether processing changed the material's effects on cells. Samples underwent sterilisation with vaporised hydrogen peroxide before being placed in direct contact with L929 fibroblast cells for 24 hours. Each condition was assessed in three independent experiments, with three technical repeats per experiment.

Under the ISO 10993-5 criterion used in the study, cell viability above 70% of the untreated control indicates a non-cytotoxic result. The recycled material recorded viability of 77.52% as pellets, 79.73% as filament, and 76.10% as printed samples. Every tested form cleared that threshold, showing that extrusion and printing did not push the material below the acceptance level under these experimental conditions.

Printed medical-grade ABS recorded 75.84% viability, close to the recycled material's 76.10%. The reference filament recorded 70.75%, compared with 79.73% for recycled filament, with both remaining above the threshold. These results support short-term compatibility with the tested cells after sterilisation, rather than establishing complete biological safety for every medical application.

The Promise Comes With Questions Worth Answering

Hospital-based printing with recycled feedstocks could help connect personalised manufacturing with efforts to keep plastic resources in use. The study demonstrated a workable route from recycled ABS pellets to accurate printed objects, supported by an initial biological assessment. Its scope covered non-implantable applications, leaving implanted devices outside the evidence presented.

The research did not measure carbon emissions, energy consumption, or production costs, so its potential environmental and financial benefits remain unquantified. Dimensional measurements and successful printing do not establish mechanical durability, repeated-sterilisation performance, or suitability for every surgical task. Broader biological testing and validation for specific devices would help determine where this material can be used responsibly.

Versalis supplied the recycled ABS, fully funded the project, and employed two of the study's authors, providing relevant context for readers assessing the findings. The most useful result is a concrete demonstration that chemically recycled ABS can combine accurate printing with an acceptable cell-toxicity result under defined laboratory conditions. For hospitals exploring less resource-intensive manufacturing, that gives future testing a practical starting point.