Clinical outcome and complications comparison between expandable and static cages in open TLIF surgery: A 2-year retrospective study

Expandable cage is designed to facilitate cage insertion from small posterior inlet and minimize neural structure over-traction, at the same time, to expand the disk space as large as possible while prevent posterior endplate breakage during cage insertion in transforaminal lumbar interbody fusion surgery. The purpose of this study is to compare radiologic and clinical outcomes between expandable and static cage, and complications of the 2 groups. Between January 2021 and January 2023, patients with lumbar spine degeneration or herniation of intervertebral disk accepting transforaminal lumbar interbody fusion surgery were included in the study. Anterior segmental height, posterior segmental height, and Cobb angle of fusion segment were recorded. These patients were divided to expandable and static group. Both group of patients were recorded of Oswestry Disability Index, back pain visual analogue score, and leg pain visual analogue score. Expandable cage group was 101 patients and static cage group was 103 patients. After operation, both groups had improvement of anterior and posterior disk height (P < .001). Fusion segmental lordosis increased after surgery in both group (P < .001). The improvement of lordosis was better in expandable group. Cages posterior migration (P < .01), cage subsidence (P = .03), and screws loosening (P = .03) were higher in static group. Expandable group had more cage breakage (P = .04),. Both groups had decreased Oswestry Disability Index and leg pain after operation (P < .001). Expandable group had better leg pain relief. Both groups had more back pain at postoperative stage. The back pain decreased at postoperative 6-month, 1-year, and 2-year gradually. Expandable group had less back pain after surgery. Expandable cage had less cage migration and cage subsidence than static cage. At the same time, expandable cage had better functional outcome than static cage. However, cage breakage rate was higher in expandable cage.