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3DP PEEK implants for chest wall reconstruction
is suitable for manufacturing customized products of the design methods and manufacturing techniques to
complex structures, with the advantage of saving raw meet the clinical needs is a very difficult task, requiring a
materials [3-5] . 3DP implants are fabricated according to lot of detail and interplay with clinical work. Establishing
the individual need of each patient. The surgical accuracy surgical standards for new implants require many clinical
and efficiency have been significantly improved using cases and an accumulation of surgical experience. Thus,
3DP implants, achieving personalized precise repair [6,7] . there are few case reports on using 3DP PEEK implants
Many 3DP titanium implants have been proven feasible in clinical practice.
and safe to repair bone defects, including spine, skull, Since 2017, our team, including a lot of engineers,
sternum, ribs, and joints [8-12] . The ideal implants should scientists, and doctors, has performed a series of
meet the needs of functional repair as well as anatomical studies on the 3DP PEEK implants for chest wall
repair. For some non-weight-bearing bones, such as the reconstruction [14,29,36-49] . First, the thoracic surgeons must
sternum and ribs, the mechanical property of titanium sort out the specific types of chest wall defects and propose
implants is much greater than cortical bone, which may the clinical implants needs for chest wall reconstruction.
even restrict the motion of thorax and cause ventilatory Then, the engineers can work with thoracic surgeons to
dysfunction after surgery [13-15] . Thus, only 3DP implants design the shape of the implant and perform the implant
with matching mechanical properties can meet the needs mechanics simulations and calculations [36-38] . Furthermore,
of chest wall reconstruction. to meet the shape and mechanical requirements of implants,
The polyether-ether-ketone (PEEK) is a member of we developed a new fused deposition modeling (FDM)
the polyaryl-ether-ketone family and was first synthesized technology to make personalized PEEK implants [39-42] .
in 1978 [16-18] . The material is a semi-crystalline aromatic Overall, 114 personalized PEEK implants have been
polymer material with thermoplasticity . The electron used to reconstruct the chest wall defect in more than 40
[17]
delocalization of the C atom of the PEEK benzene ring hospitals in China [14,29] . The design and manufacturing
forms a π-π conjugation, and the lone pair of electrons of the process of PEEK implants has also changed with the
adjacent O atom can form a p-π conjugation with the C atom increase in clinical applications. The surgical methods
of the benzene ring. This is a very stable chemical structure are constantly improved as the applications increase, and
that enables PEEK to withstand the corrosion of most we further establish the surgical standards of 3DP PEEK
chemical reagents except concentrated sulfuric acid [19-21] . In implants for chest wall reconstruction in Chinese clinical
addition, PEEK has good radiation resistance, and gamma guidelines [43,44] . In addition, new clinical problems, such as
rays will not cause any obvious free radical residues on the incision ulcers and respiratory restriction, have prompted
surface of PEEK . The radiolucency of PEEK material is surgeons and engineers to work together to develop new
[22]
good because it will not produce any imaging artifacts, and implant designs and fabrication processes. The surface
also, it will not affect the subsequent clinical imaging results amination grafting and sulfuric acid etching methods
after implantation surgery . Concerning the mechanical were developed to overcome the strong hydrophobicity
[23]
property of PEEK, the elastic modulus of PEEK is similar of PEEK material, and the wavy elastic structure of
to that of cortical bone, which can effectively avoid bone implants can make the thorax possess a better degree
[38,45-49]
non-union caused by stress shielding. Till now, numerous in of motion . Herein, we systematically summarize
vitro studies have confirmed the low cytotoxicity of PEEK all the details of 3DP PEEK implants for chest wall
to various cells [24,25] . After long-term implantation in the reconstruction from a clinical need for biofabrication and
body, it will not release toxic and harmful ions in the follow- discuss its future clinical industrialization perspectives.
up period [26,27] . The high-temperature resistance, chemical 2. Accurate design methods for 3DP PEEK
properties, radiolucency, good mechanical property, and implants
low cytotoxicity of PEEK make it a suitable candidate for
surgical implants [23,28-32] . The chest wall reconstruction could be grouped into rib
The main manufacturing method of PEEK implants reconstruction and sternum-rib hybrid reconstruction,
is digital control mechanical processing by cutting the depending on whether the sternum was included,
PEEK block mold [33,34] . The traditional digital control and the typical situations are shown in Figure 1. The
mechanical processing is convenient for rapid batch rib reconstruction could be categorized into three
production but it consumes more raw materials . This types based on the position: in-suit rib reconstruction
[35]
method is also not suitable for customized products with (Figure 1A), costal arch reconstruction (Figure 1B) and
complex structures. Thus, traditional surgery can only use vertical reconstruction (Figure 1C), and the sternum-rib
implants with fixed specifications, which is difficult to hybrid reconstruction could also be divided into three
meet the requirements of personalized and precise repair. types: Whole sternum reconstruction (Figure 1D), upper
PEEK is an excellent raw material for 3DP technology segment sternum reconstruction (Figure 1E), and upper
due to its thermoplasticity . Nevertheless, developing segment sternum reconstruction (Figure 1F) .
[50]
[35]
224 International Journal of Bioprinting (2022)–Volume 8, Issue 4