3D printing in orthopaedics 3D tissue regeneration

1. 3D Printing For Hip Implant
Applications
A review of an article published in
Polymers(MDPI) by Obinna Okolie ,
Iwona Stachurek , Balasubramanian
Kandasubramanian
and James Njuguna
1

2. I will be dealing with........
• Introduction
• 3D printing for Hip Replacement
• 3D Hip Tissue Regeneration
• Challenges, Ethics and Trends in 3D Printing of
Implants
• Conclusions

3. INTRODUCTION
• Hip pain is a significant issue affecting a large
portion of the global population, especially
the elderly and children.
• Conditions leading to hip pain include
arthritis, injuries, pinched nerves, cancer, and
lifestyle factors.
•

4. • Non-surgical treatments are typically the
first line of action, but hip replacement
surgery may be necessary when
conservative measures fail.
• 3D printing provides advantages over
conventional imaging techniques like CT
and MRI, offering detailed models for
surgical planning and simulation.

5. Direct 3D Printing for Hip
Replacement
• Introduction to 3D Printing:
–3D printing involves layer-by-layer material
creation through a computerized technique.
–The first use in the early 1990s was
centered on the concept of conventional
inkjet printers, using drop-on-powder or
binder jetting.

6. • Printing Process Overview:
–The technology builds successive layers,
adding height to create three-dimensional
objects.
–Unlike 2D inkjet printers, 3D printers utilize
liquid binder solution layered on a
powdered bed.
–The process involves nozzle emission,
powder excess removal, reduction of the
platform, and continuous layer deposition.
.

7. Formation of scaffolds fabricated
through inkjet 3D printing

8. • Comparison with Extrusion-Based Technique:
–Inkjet 3D printing is favoured over
extrusion-based techniques for biomedical
applications, producing intricate scaffolds in
different shapes.
• Use of Inkjet Printing in Various Studies:
– Inkjet 3D printing is employed in studies for
producing HA-based scaffolds, drug release
agents, and cellular structures for tissue
engineering

9. • .
• Challenges in Hip Implants:
– Current hip implant materials, including metals and
alloys, pose challenges due to their stiffness,
altering load transmission and leading to bone
remodeling.
• Concerns with Polymer Scaffolds:
– The creation of 3D printed polymer scaffolds for
bio applications faces challenges, including issues
with hardening techniques and potential pore
collapse.

10. Fused Deposition Modelling (FDM) for
Hip Replacement
• FDM Process Overview:
– FDM involves the use of thermo sensitive
polymers that undergo heating above their glass
transition temperature, leading to solid medium
deposition.
– Initially used for 3D polymer structures, FDM has
evolved to produce ceramic and ceramic/polymer
composites known as fused deposition of
ceramics.
•

11. • Printing Technique:
–A thermoplastic polymeric filament is
unwound and extruded through a hot nozzle
onto a fabrication base.
–The polymer cures upon settling on the
platform, and successive layer-by-layer
depositions result in the final CAD structure.

13. • Applications and Examples:
–FDM is used to create 3D geometries,
fabricate specific structures like acetabulum
for hip replacement.
–Acrylonitrile butadiene styrene (ABS) is a
commonly used material for FDM, known
for its feasibility and ease of polymer-based
scaffold fabrication.
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• .
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14. • Advantages and Limitations:
–FDM offers advantages such as low toxicity
risk from solvents and applicability on
scaffolds without cells or bioactive
molecules.
–Limitations include challenges in selecting
the right thermoplastic material, hindering
versatility. ABS is commonly used due to its
suitability

15. • Evaluation of FDM in Meniscus Fabrication:
– A study by Borges et al. evaluated the potential of
FDM in creating artificial meniscus using
polycarbonate-urethane (PCU) and ultra-high-
molecular-weight polyethylene (UHMWPE).
– The introduction of UHMWPE did not reduce wear
and friction, attributed to a larger surface
roughness, indicating the necessity for surface
treatment.

16. Selective Laser Sintering (SLS) for Hip
Replacement
• SLS Process Overview:
– SLS involves a laser reproducing object shapes on
powder, fusing material layer by layer until the
object is complete.
– Applicable in ceramics, metals, and polymers,
precision depends on powder fineness and laser
precision, allowing for detailed and biomimetic
structures..

18. • Biodegradable Polymers in SLS:
–Biodegradable and biocompatible
polymers like polyvinyl alcohol,
polycaprolactone, and
polyetheretherketone have been used
for scaffolds

19. • SLS Applications and Studies:
–SLS has been applied to create
scaffolds with varying materials,
including biocomposite sludge for
osteoblast cell growth.
–Challenges include the need for
powdered material to endure laser
heat and scaffold shrinking during
sintering.

20. Stereolithography (SLA) for Hip
Replacement
• Overview of Stereolithography (SLA):
– SLA was the first commercially available 3D
printer.
– It uses a liquid polymer source undergoing light-
treated chemical reactions.
– A photocurable and photosensitive polymeric
material is exposed to a UV light range (300–400
μm) to fabricate scaffolds layer by layer.
• .

21. .

22. • Optimization and Benefits:
– The process can be optimized by adjusting factors
like laser speed, solution viscosity, and power.
– Benefits include potential control during use,
accurate scaffold geometries closely mimicking
CAD design, and localized drug delivery

23. • Localized Drug Delivery with SLA:
– Drugs, such as bone morphogenetic protein-2
(BMP-2), can be embedded in PLGA microspheres
suspended in a PPF/DEF photopolymer and
printed via SLA for gradual release, promoting
bone cell regrowth.

24. .Applications and Studies:
– PPF, a biodegradable polymer, has been
extensively used for tissue engineering via SLA.
– Chitosan, a natural polymer, has also been used to
fabricate SLA-printed scaffolds, demonstrating
good in vitro cytocompatibility and bone tissue
regrowth.

25. • Material Variety:
– SLA is not limited to soft biomaterials and has been
applied to hard materials, such as ceramics/polymer
composites.
– Ceramic/polymer composites, like bioactive glass and
PCL, have been successfully fabricated using SLA,
providing uniform dispersion for rapid ion release and
cell bioreactions.
• Comparison with Other Techniques:
– SLA has advantages in terms of fabrication speed,
resolution, and control compared to conventional layer-
by-layer 3D printing techniques.

26. Surface Modifications of 3D Printed
Implants
• Surface modification plays a crucial role in
enhancing the properties of 3D printed
implants, particularly in terms of surface
roughness, porosity, and bioactivity. Various
techniques and methods are employed to
modify the surface of these implants, aiming
to improve their interaction with biological
systems and ultimately enhance their
functionality.

27. • Importance of Surface Modification: Surface
properties of implants often require
enhancement before use. Modifying the
chemical and physical composition of the
surface can significantly influence biomaterial-
cellular interactions, including adhesion,
inflammatory reactions, cell differentiation,
and protein production.

28. • Challenges and Techniques: Achieving
uniform and reliable modifications on the
surface topography of large porous 3D
scaffolds poses technical challenges.
Electrochemical polishing (EP) and silanization
are among the techniques used to improve
surface performance, bioactivity, and cell
adhesion.

29. • Composite and Additive Integration:
Combining 3D printing with surface
modifications, such as sol-gel techniques,
facilitates the incorporation of additives like
biominerals and magnetic nanoparticles.
These additives can enhance mineralization,
bone regeneration, and cellular behavior.

30. • Control of Surface Features: While
advancements in 3D printing allow for precise
control over macroscopic scaffold structures,
controlling surface features at the microscopic
level remains a challenge. Strategies like 4D
printing and micro arc oxidation (MAO) are
emerging to address this issue and fine-tune
scaffold surfaces for specific biological
responses.

31. 3D Hip Tissue Regeneration
• Bone grafting and replacement operations,
including hip replacements, are in high
demand, with over four million procedures
performed annually worldwide.
• The development of bioactive 3D scaffolds
supporting bone regeneration is a crucial area
of interest in bone tissue engineering, with 3D
printing playing an increasingly important
role.

32. • Composite scaffolds combining materials like
polymers, ceramics, and hydrogels can
enhance bioactivity and mimic bone
properties more effectively.
• A perfect 3D scaffold should be
biocompatible, biodegradable, mechanically
similar to native tissue, and promote cell
attachment, proliferation, and differentiation.

33. • Tissue engineering aims to develop functional
tissues for repair, preservation, and
enhancement of tissue functionality, while
regenerative medicine focuses on curing
rather than just treating complex diseases.
• Autografts and allografts have limitations and
risks, leading to increased interest in tissue
engineering approaches using synthetic
biomaterials and 3D printing.

34. • Biomaterials for tissue engineering
should be porous, biocompatible,
reproducible, biodegradable, and
capable of supporting cell
attachment, growth, and
differentiation.

35. • Hip replacement surgery techniques
continue to advance, with a focus on
tissue preservation, minimal
invasiveness, and faster patient recovery.
• Regenerative therapies, including stem
cell injections and bioengineered tissues,
show promise in hip defect treatment,
but challenges remain in fabricating
tissues with embedded vascular
networks.

36. Challenges, Ethics and Trends in 3D
Printing of Implants
• Despite advancements in 3D printing technology for
scaffold fabrication at nanoscales, its adoption for
clinical applications faces obstacles in biological, cost,
engineering, and safety aspects.
• Challenges include ensuring bioactivity,
reproducibility, and producibility of scaffolds, as well
as addressing issues related to material purity, design
variability, and human error.
• Quality assurance of 3D printed implants is crucial,
requiring protocols for material qualification, process
control, and post-processing.

37. • Ethical considerations, including patient safety and
informed consent, are paramount in the
development and application of 3D printing
treatments for biomedical purposes.
• Regulatory frameworks are needed to address
specific concerns related to 3D bioprinting in
medicine, including limits, risks, clinical trials, ethical
laws, and efficacy compared to conventional
treatments.
• Further research is necessary to better understand
the uncertainties and risks associated with 3D
bioprinting and to develop appropriate regulations to
mitigate potential negative impacts.

38. CONCLUSION
• 3D printing technology for scaffolds is rapidly
advancing, aiming to mimic the properties of
the extracellular matrix (ECM) and provide
mechanical strength, adequate pore size for
nutrient movement, and support cell growth.
• The research involves integrating biological
and mechanical engineering processes,
including hip mechanics evaluation, material
selection, fabrication, surface treatment, and
product study.

39. • Composites and hybrid materials are
promising for future scaffold production,
addressing limitations of printing techniques
and biomaterials.
• Current emphasis in 3D printing for medicine
is on tissue replacement/regeneration, both in
vivo and possibly in vitro.

40. • Thorough evaluation of scaffold performance and
quality is crucial for successful tissue engineering
applications.
• 3D printed scaffolds are expected to play a
significant role in healing hip pains from
damaged/diseased tissues and improving quality
of life.
• Challenges remain, including scalability, control,
and material performance, requiring further
research for advancement in total hip
replacement (THR) using 3D printing technology.
•