3D-Printed Porous Titanium versus Polyetheretherketone Cages in Lumbar Interbody Fusion: A Prospective, Multicenter, Randomized Controlled Trial with Bone Mineral Density Stratification.

Abstract

3D-printed porous titanium (3D-Ti) cages are an alternative to polyetheretherketone (PEEK) cages in lumbar interbody fusion; however, prospective comparative evidence evaluating biomechanical performance in compromised bone quality remains limited. To compare radiologic and clinical outcomes of 3D-Ti versus PEEK cages in single-level lumbar interbody fusion, focusing on the impact of bone mineral density (BMD) on structural stability. Prospective, multicenter, randomized controlled trial PATIENT SAMPLE: Sixty-six patients with degenerative lumbar disease were randomized to the PEEK (n=32) or 3D-Ti group (n=34); 55 patients completed the 2-year follow-up. The primary outcome was the 2-year CT-based fusion rate. Secondary outcomes included cage subsidence, sagittal parameters, disc height index, VAS, ODI, MCID achievement rate, and complications. Patients were randomized 1:1 to receive a PEEK or 3D-Ti cage. Blinded evaluators assessed radiographic outcomes. Per-protocol analysis was conducted for patients who completed the 2-year follow-up. Patients were stratified by preoperative T-scores into normal, osteopenia, and osteoporosis subgroups. Interaction regression and receiver operating characteristic (ROC) curve analyses identified subsidence risk thresholds. Baseline demographics were comparable. At 2 years, overall fusion rates were comparable between the 3D-Ti and PEEK groups (92.9% vs. 92.6%, p=1.000; ITT: 76.5% vs. 78.1%, p=1.000). However, the overall subsidence rate was significantly lower in the 3D-Ti group (7.1% vs. 37.0%, p=0.010). Outcomes were comparable in normal bone quality, but profound differences emerged in osteoporosis. Osteoporotic PEEK patients exhibited a significantly higher subsidence rate than 3D-Ti patients (58.3% vs. 12.5%, p=0.039), translating to inferior VAS back pain (p=0.012) and ODI scores (p=0.018). Subsidence depth correlated with lower T-scores in PEEK (rho=-0.68, p<0.001) but not 3D-Ti. ROC analysis identified a T-score cut-off of -2.4 (AUC 0.865) for predicting elevated subsidence risk with PEEK. While PEEK and 3D-Ti cages provide comparable fusion rates and outcomes in normal bone, 3D-Ti cages demonstrate significantly superior subsidence resistance in osteoporotic patients CLINICAL TRIAL REGISTRATION: Clinical Research Information Service (CRIS), No. [KCT-0006624].