Biological evaluation and finite-element modeling of porous poly(para-phenylene) for orthopaedic implants

Abstract

PEEK has been widely used in orthopaedic surgery; however, the ability to utilize PEEK for advanced fabrication methods, such as 3D printing and tailored porosity, remain challenging. We present a promising new orthopaedic biomaterial, Poly(para-phenylene) (PPP), which is a novel class of aromatic polymers with higher strength and stiffness than polyetheretherketone (PEEK). PPP has exceptional mechanical strength and stiffness due to its repeating aromatic rings that provide strong anti-rotational biaryl bonds. Furthermore, PPP has an amorphous structure making it relatively easier to manufacture (via molding or solvent-casting techniques) into different geometries with and without porosity. This ability to manufacture different architectures and use different processes while maintaining mechanical properties makes PPP a very promising potential orthopaedic biomaterial which may allow for closer matching of mechanical properties between the host bone tissue while also allowing for enhanced osseointegration. In this manuscript, we look at the potential of porous and solid PPP in comparison to PEEK. We measured the mechanical properties of PPP and PEEK scaffolds, tested these scaffolds in vitro for osteocompatibility with MC3T3 cells, and then tested the osseointegration and subsequent functional integration in vivo in a metaphyseal drill hole model in rat tibia. We found that PPP permits cell adhesion, growth, and mineralization in vitro. In vivo it was found that porous PPP significantly enhanced mineralization into the construct and increased the mechanical strength required to push out the scaffold in comparison to PEEK. This is the first study to investigate the performance of PPP as an orthopaedic biomaterial in vivo. PPP is an attractive material for orthopaedic implants due to the ease of manufacturing and superior mechanical strength.

The current state of PEEK implant osseointegration and future perspectives: a systematic review

“…Porous PPP demonstrated higher osseointegration and bone volume as compared to the other implants. Similar findings were observed by histomorphometric analysis (Ahn et al, 2018).…”

“…PEEK demonstrated significantly low resistance to bacterial infection after incubation with Staphylococcus epidermidis, which led to compromised osseointegration (Webster et al, 2012). Ahn et al (2018) investigated the use of porous and solid poly[para-phenylene] (PPP) and PEEK implants. In vivo assessment was conducted to evaluate osseointegration.…”

“…Clinically, osseointegration is defined as asymptomatic rigid fixation of alloplastic materials in the bone under functional loading (Zarb and Albrektsson, 1991). The microscopic definition of osseointegration is the direct contact between the implant surface and the surrounding bone without interposition of any fibrous or connective tissue (Albrektsson et al, 2017). Recent studies referred to osseointegration as the body's reaction (bone) to isolate the foreign body (implant) (Albrektsson et al, 2017).…”

“…The microscopic definition of osseointegration is the direct contact between the implant surface and the surrounding bone without interposition of any fibrous or connective tissue (Albrektsson et al, 2017). Recent studies referred to osseointegration as the body's reaction (bone) to isolate the foreign body (implant) (Albrektsson et al, 2017). Therefore, understanding osseointegration at all levels (clinical, histological and conceptional) is crucial.…”

Desktop-Stereolithography 3D Printing of a Polyporous Extracellular Matrix Bioink for Bone Defect Regeneration

“…To conquer the shortcomings that pure ECM is unable to provide, like adequate mechanical strength, the scaffold processing techniques are taken into consideration. Conventional scaffold processing techniques that fabricate various tissues, such as phase separation ( Fang et al, 2019 ), freeze-drying ( Grenier et al, 2019 ; Zhang L. et al, 2019 ), solvent casting ( Ahn et al, 2018 ; Mao et al, 2018 ), gas foaming ( Kaynak Bayrak et al, 2017 ; Catanzano et al, 2018 ), and electrospinning ( Chan et al, 2019 ), cannot precisely control pore size, geometry, and interconnectivity of the scaffolds. However, 3D printing has emerged as a brand-new material processing approach, which largely overcomes these difficulties, allowing us to fabricate more bionic scaffolds for bone transplantation and to repair the bone defect in a clinical setting ( Do et al, 2015 ).…”