Objective:

To examine the effect of static versus expandable polyetheretherketone (PEEK) cages on both clinical and radiographic outcomes.

Methods:

A retrospective cohort study was conducted on patients who underwent one-level transforaminal lumbar interbody fusion (TLIF) with either a static or expandable PEEK cage. Patient outcomes were obtained from chart review and radiographic outcomes were measured using standing, lateral radiographs. Recovery ratios (RR) and the proportion of patients achieving the Minimally Clinically Important Difference (MCID) were calculated for ODI, PCS-12, MCS-12, VAS Back, and VAS Leg at 1 year and compared between groups. Multivariate linear regression analysis was performed to determine the effect of cage type on the change in PROMs, controlling for demographic factors.

Results:

A total of 240 patients (137 Static, 103 Expandable) were included in the final analysis. ΔPCS-12 scores at 3 months were significantly greater for the static group (16.0 vs. 10.0, p=0.043) compared to the expandable group. Multivariate regression demonstrated that use of an expandable cage was associated with greater improvements in ΔODI (β: -7.82, p=0.048) at 1 year. No differences were found in the perioperative change in sagittal spinal alignment within or between groups at 1 year. Subsidence rates failed to show any statistically significant difference between the two groups.

Conclusions:

TLIF with an expandable PEEK cage is an independent predictor of improved ODI scores at 1 year. Our study showed no significant differences in subsidence rates or changes in sagittal spinal alignment between static and expandable PEEK cages.