Effects of Surface Topography and Chemistry on Polyether-Ether-Ketone (PEEK) and Titanium Osseointegration

Abstract

Study Design. An in vivo study examining the functional osseointegration of smooth, rough, and porous surface topographies presenting polyether-ether-ketone (PEEK) or titanium surface chemistry. Objective. To investigate the effects of surface topography and surface chemistry on implant osseointegration. Summary of Background Data. Interbody fusion devices have been used for decades to facilitate fusion across the disc space, yet debate continues over their optimal surface topography and chemistry. Though both factors influence osseointegration, the relative effects of each are not fully understood. Methods. Smooth, rough, and porous implants presenting either a PEEK or titanium surface chemistry were implanted into the proximal tibial metaphyses of 36 skeletally mature male Sprague Dawley rats. At 8 weeks, animals were euthanized and bone–implant interfaces were subjected to micro-computed tomography analysis (n = 12), histology (n = 4), and biomechanical pullout testing (n = 8) to assess functional osseointegration and implant fixation. Results. Micro-computed tomography analysis demonstrated that bone ingrowth was 38.9 ± 2.8% for porous PEEK and 30.7 ± 3.3% for porous titanium (P = 0.07). No differences in fixation strength were detected between porous PEEK and porous titanium despite titanium surfaces exhibiting an overall increase in bone–implant contact compared with PEEK (P < 0.01). Porous surfaces exhibited increased fixation strength compared with smooth and rough surfaces regardless of surface chemistry (P < 0.05). Across all groups both surface topography and chemistry had a significant overall effect on fixation strength (P < 0.05), but topography accounted for 65.3% of the total variance (ω2 = 0.65), whereas surface chemistry accounted for 5.9% (ω2 = 0.06). Conclusions. The effect of surface topography (specifically porosity) dominated the effect of surface chemistry in this study and could lead to further improvements in orthopedic device design. The poor osseointegration of existing smooth PEEK implants may be linked more to their smooth surface topography rather than their material composition. Level of Evidence: N/A

Effect of surface topography on in vitro osteoblast function and mechanical performance of 3D printed titanium

“…If 3D printed roughness does in fact aid in implant fixation, artificial roughness will be designed on implant surfaces opposed to bone to increase early fixation at the bone‐implant interface. In addition, it is well known that porosity enhances osseointegration in metal implants 37 – 42 and recent work has shown that porosity is a larger factor in controlling osseointegration versus surface roughness alone 43,44 . Osseous integration remains a challenging problem in orthopedic implants likely requiring a multifaceted solution.…”

Bioinspired Modifications of PEEK Implants for Bone Tissue Engineering

“…Compared to rough surfaces, porous PEEK surfaces exhibit increased osteoblastic differentiation and bonding strength with bone (Torstrick et al, 2018(Torstrick et al, , 2020. Numerous techniques have been applied to develop porous structures on the PEEK surface, including sulfonation, melt extrusion, porogen templating, and PIII technique (Zhao et al, 2013;Lu et al, 2014;Evans et al, 2015;Torstrick et al, 2016;Hieda et al, 2017;Yabutsuka et al, 2017;Wu et al, 2018;Yuan et al, 2018;Conrad and Roeder, 2020;Swaminathan et al, 2020;Wan et al, 2020).…”

Femtosecond laser optimization of PEEK: efficient bioactivity achieved by synergistic surface chemistry and structures

“…Indeed, the stable chemical structure of PEEK makes it innately inert and keeps it from binding to bone directly, resulting in inferior osseointegration, which greatly hinders its further clinical application in the field of bone repair. 4,[7][8][9] Thus far, various surface modification techniques have been developed to improve the bioactivity of PEEK, such as thermal plasma spray, 10 cold spray, 11 spin coating, 12 chemical deposition, 13 sputtering, 14,15 ion beam assisted deposition, 16 laserassisted biomimetic process 17 and microwave assisted coating. 18 The main purpose is to induce calcium phosphate (Ca-P) coating on the PEEK surfaces, which can not only improve the osseointegration of the material but even endow it with excellent osteoconduction.…”