75. Evaluation of cage subsidence in standalone lateral lumbar interbody fusion: Novel 3D printed titanium versus polyetheretherketone (PEEK) cage

Abstract

<h3>BACKGROUND CONTEXT</h3> Lateral lumbar interbody fusion (LLIF) is a common treatment for degenerative spine diseases. However, implant subsidence is a prevalent complication especially in stand-alone cases, which can negatively affect patient outcomes. The novel 3D-printed titanium (Ti) cages with porous architecture are reportedly more osteoconductive, maximize bone-to-implant contact, and have more compressive shear strength under physical force. Nevertheless, the subsidence rate of these new Ti cages compared to polyetheretherketone (PEEK) cages has not been investigated in standalone cases. <h3>PURPOSE</h3> This study aims to compare the early subsidence rate (6-12 months) of standalone Ti vs PEEK interbody cages after LLIF. <h3>STUDY DESIGN/SETTING</h3> Retrospective study. <h3>PATIENT SAMPLE</h3> A total of 113 patients and 186 levels. <h3>OUTCOME MEASURES</h3> Early cage subsidence. <h3>METHODS</h3> A retrospective study of 113 patients (186 levels) who underwent LLIF surgery with Ti or PEEK cages was conducted. Early subsidence was measured in each treated level using the Marchi et al. classification in radiographs or CT scans acquired at 6-12 months follow-up. Multivariate logistic regression analyses with generalized mixed models, setting subsidence as the outcome variable and including cage type (Ti vs PEEK) as well as significant and trending variables (p<0.10) in univariate analyses, was conducted. <h3>RESULTS</h3> In total, 51 female and 62 male patients were analyzed. The median (IQR) age at surgery was 60.0 (51.0-70.0) years. Of the 186 levels, 119 levels were treated using PEEK and 67 levels with Ti cages. The overall subsidence rate for Grades I-III was significantly less in the Ti vs the PEEK group (p=0.003). For high-grade subsidence (Grade II or III), Ti cages also demonstrated a subsidence rate (3.0%) that was significantly less compared to PEEK cages (18.5%)(p= 0.002). Multivariate analysis showed that patients treated with Ti cages were less likely to develop severe subsidence compared to those treated with PEEK (OR= 0.05, 95%CI= 0.01, 0.30)(p= 0.001). <h3>CONCLUSIONS</h3> Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients. <h3>FDA DEVICE/DRUG STATUS</h3> Titanium and PEEK Cage (Approved for this indication).