Table 3.

Techniques for changing surface roughness.

Techniques for porous surface preparation	Modification strategy	Experimental category	Evidence of improved anti-inflammation	Reference
Sulfonation	Concentrated sulfuric acid treatment	in vivo	Decreased TNF-α concentration, increased IL-10 concentration, and promoted M2 macrophage polarization	[144]
	Concentrated sulfuric acid treatment followed by immersion in ASP solution and grafting of BFP onto sulfonated PEEK surface	in vitro	Down-regulated COX-2 and IL-6 expression	[146]
Acid etching	HNO3 treatment	in vitro	Enhanced cell adhesion	[147]
	HF and HNO3 treatment	in vitro	Down-regulated the expression of proinflammatory cytokines, promoted M2 macrophage polarization	[148]
3D printing technology prepared porous PEEK	3D printed PEEK etched with sulfuric acid	in vivo	Reduced fibrous tissue formation, decreased the expression of IL-1β and TNF-α	[149]
		in vitro	Promoted M2 macrophage polarization and enhanced secretion of anti-inflammatory cytokines IL-4 and IL-10	[150]
Extrusion under heat and pressure	Sodium chloride powder and PEEK powder were extruded under high temperature and high pressure and dissolved in sodium chloride in water after cooling	in vivo	Reduced fibrous tissue formation	[141]
LBL self-assembly	Alternate dipping in PAA/PAH solution, then rinsing in acid solution	in vitro	Reduced the level of proinflammatory factors, down-regulated the TNF-α and JAK-STAT signaling pathways, and promoted M2 macrophage polarization	[151]
Argon PIII	Argon PIII and subsequent hydrogen peroxide treatment	in vitro	Reduced fibrous tissue formation around the implant	[152]