Comparative Outcomes of Unilateral versus Bilateral Cage Placement in Lumbar Interbody Fusion: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract Study design: Systematic review and meta-analysis Objective: To compare the safety and efficacy of unilateral versus bilateral cage placement in lumbar interbody fusion. Summary of background data: Lumbar interbody fusion is a common surgical procedure designed to treat chronic spinal conditions. The procedure often involves the use of intervertebral cages to increase stability and promote fusion. While bilateral cage placement has traditionally been favored, recent studies have questioned its necessity. Methods: A comprehensive search across PubMed, Scopus, and Cochrane databases identified eight eligible RCTs involving 509 patients. The primary outcome focused on the spinal fusion rate, whereas the secondary outcomes included surgery related outcomes (operative time, estimated blood loss, length of stay), patient-reported outcomes (visual Analog Scale, Oswestry Disability Index, patient satisfaction) and complications. Results: The analysis revealed no significant difference in successful spinal fusion rates between the two groups (p=0.41). Unilateral cage placement was associated with significantly shorter operation time (p<0.0001) and reduced estimated blood loss (p<0.0001), whereas hospital stay was not affected by the number of cages used (p=0.24). Patient-reported outcomes, including VAS back score (p=0.61), VAS leg score (p=0.64), ODI score (p=0.23) and patient rate of results (p=0.55) showed no substantial differences between the two groups. Patients in the unilateral group had a lower overall risk for complications (p=0.03), but no difference in the risk of cage migration was noted between the two groups (p=0,97). Conclusions: Unilateral cage placement in lumbar interbody fusion is as effective as bilateral for achieving fusion without compromising patient outcomes. Furthermore, offers significant advantages, including reduced operative time, blood loss and reduced risk for complications.