Biomechanical analysis between PEEK and titanium screw-rods spinal construct subjected to fatigue loading

Area of Science:

• Spinal biomechanics
• Biomaterials science
• Orthopedic surgery

Background:

• Polyetheretherketone (PEEK) rods are proposed for improved spinal load sharing compared to Titanium rods.
• Previous studies on PEEK vs. Titanium rods relied on single-load testing, leaving fatigue performance unknown.

Purpose of the Study:

• To compare the in vitro biomechanical performance of Polyetheretherketone (PEEK) and Titanium rods under fatigue loading.
• To evaluate differences in load sharing, adjacent segment effects, and bone stress between PEEK and Titanium constructs.

Main Methods:

• In vitro fatigue loading test using porcine specimens (n=24).
• Specimens were assigned to intact, Titanium rods, or PEEK rods groups.
• Disk height, intradiscal pressure (IDP), rod stress, and screw-bone interface stress were measured.

Main Results:

• PEEK rods maintained disk height and IDP comparable to intact spines.
• Titanium rods showed significant loss of disk height and IDP at adjacent levels.
• PEEK rods exhibited significantly less bone stress at the screw-bone interface than Titanium rods.

Conclusions:

• PEEK and Titanium rods demonstrate distinct biomechanical characteristics under fatigue loading.
• PEEK rods may offer benefits in reducing adjacent segment disease.
• PEEK constructs show potential for lower implant failure rates compared to Titanium.