Polyetheretherketone vs titanium cages in oncological spine surgery: Beyond mechanics toward oncological precision

Table 1 Integrated comparison of interbody cage materials in oncological spine surgery across biomechanical, biological, radiological, and clinical domains

Domain	Property	Titanium (Ti)	PEEK	CFR-PEEK	Evidence type	Certainty
Biomechanics	Elastic modulus/stiffness	High (approximately 110 GPa) → increased rigidity	Low (approximately 3.6 GPa) → reduced stress shielding	Intermediate (fiber-dependent)	Mechanistic	Moderate
	Load-bearing capacity	High; excellent immediate stability	Moderate	Moderate-high	Mechanistic	Low
	Stress shielding	Increased due to stiffness mismatch	Reduced	Reduced	Mechanistic	Low
Implant-bone interaction	Osteointegration	Strong, especially porous/3D Ti[4,7]	Limited (bioinert); may require modification[4]	Limited; similar to PEEK	Mechanistic + preclinical	Moderate
	Biological fixation	Reliable early fixation	Slower; graft-dependent	Similar to PEEK	Mechanistic	Low
Radiology/oncology	Imaging artifact (computed tomography/magnetic resonance imaging)	Significant artifact limiting assessment[1,2,4]	Radiolucent; clear visualization[1,2,4]	Radiolucent; similar to PEEK[12-15,18]	Mechanistic + clinical	High
	Tumor surveillance	May obscure recurrence/margins[1,2]	Improved visualization[12-15,18]	Improved visualization[12-15,18]	Clinical + mechanistic	Moderate
	Radiotherapy compatibility	Dose perturbation possible[2,18]	Minimal interference[2,18]	Minimal interference[2,18]	Clinical + experimental	Moderate
Clinical outcomes	Fusion rate	No overall difference; lumbar advantage (OR: 2.12)[6,22]	Comparable overall; lower in lumbar subgroup[6]	No data	Clinical (meta-analysis)	Moderate
	Subsidence	Higher risk: 2.17[6]	Lower risk[6]	No data	Clinical (meta-analysis)	Moderate
	PROMs (ODI, VAS)	No meaningful difference[5]	Comparable outcomes[5]	No evidence	Clinical (RCT/meta-analysis)	High
	Complications	No difference[6,22]	Similar safety[6,22]	Comparable (limited data)[12-15,18,20]	Clinical	High
Special scenarios	Compromised bone (oncologic/irradiated)	Strong support; advantageous in instability[1,4]	Potential fixation concerns	Promising but unproven	Mechanistic + limited clinical	Low
Material innovation	Ti-coated PEEK	-	Improved osteointegration vs PEEK[5]	Emerging	Clinical	Moderate
Summary	Net clinical effect	Modest fusion benefit offset by subsidence and imaging artifact	Balanced profile with imaging and RT advantages	Insufficient evidence	Synthesis	-

PEEK: Polyetheretherketone; CFR-PEEK: Carbon fiber-reinforced polyetheretherketone; OR: Odds ratio; PROMs: Patient-reported outcomes; ODI: Oswestry Disability Index; VAS: Visual analogue scale; RCT: Randomized controlled trial; RT: Radiation therapy.