Subsidence Rates Associated With Porous 3D-Printed Versus Solid Titanium Cages in Transforaminal Lumbar Interbody Fusion.

Study design: Retrospective Cohort Study.

Objective: To determine whether 3D-printed porous titanium (3DPT) interbody cages offer any clinical or radiographic advantage over standard solid titanium (ST) interbody cages in transforaminal lumbar interbody fusions (TLIF).

Methods: A consecutive series of adult patients undergoing one- or two-level TLIF with either 3DPT or ST "banana" cages were analyzed for patient reported outcome measures (PROMs), radiographic complications, and clinical complications. Exclusion criteria included clinical or radiographic follow-up less than 1 year.

Results: The final cohort included 90 ST interbody levels from 74 patients, and 73 3DPT interbody levels from 50 patients for a total of 124 patients. Baseline demographic variables and comorbidity rates were similar between groups (P > .05). Subsidence of any grade occurred more frequently in the ST group compared with the 3DPT group (24.4% vs 5.5%, respectively, P = .001). Further, the ST group was more likely to have higher grades of subsidence than the 3DPT group (P = .009). All PROMs improved similarly after surgery and revision rates did not differ between groups (both P > .05). On multivariate analysis, significant positive correlators with increasing subsidence grade included greater age (P = .015), greater body mass index (P = .043), osteoporosis/osteopenia (P < .027), and ST cage type (P = .019).

Conclusions: When considering interbody material for TLIF, both ST and 3DPT cages performed well; however, 3DPT cages were associated with lower rates of subsidence. The clinical relevance of these findings deserves further randomized, prospective investigation.