Expandable Versus Static Cages for Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spondylosis

Objective: Expandable cages have been used in lumbar interbody fusion in recent years. These cages allow a customizable fit within the intervertebral space, enabling surgeons to restore alignment and disc height. Various types of expandable cages are currently available. However, the benefits of expandable titanium cages remain unclear, with limited evidence.Methods: This prospective, single-center cohort study enrolled patients undergoing transforaminal lumbar interbody fusion with expandable or static cages by a single surgeon. Titanium expandable cages were used in the intervention group, while polyetheretherketone static cages were applied in the control group. The clinical and radiological outcomes were evaluated preoperatively and at 1, 3, and 6 months postoperatively. The fusion rate assessed by dynamic radiography was significantly higher for the expandable cage group than in the static cage group at a 6-month follow-up (95% vs. 65%). The radiological outcomes, including disc height index, segmental lordosis, and lumbar lordosis, were similar in the 2 groups. There was no significant difference in the subsidence rate.Results: There were 20 patients in each group, with similar patient characteristics. The visual analogue scales for back and leg pain significantly improved in both groups. There were no significant differences between the groups in clinical outcomes.Conclusion: The expanded cages led to comparable outcomes. The subsidence rate of the titanium expandable cages was similar to that of the static cages. The newly designed expandable cage may accelerate fusion by reducing iatrogenic injuries to the endplate.