Early radiological and perioperative outcomes of a boomerang-shaped expandable cage versus static cages in single-level minimally invasive transforaminal lumbar interbody fusion.
- 1Department of Orthopedic Surgery, Hachiya Orthopaedic Hospital, Nagoya, Japan.
- 2Division of Orthopedic Surgery, Fujita Medical University Graduate School of Medicine, Toyoake, Japan.
Abstract
Expandable cages have been reported to improve intervertebral disc height (DH) and segmental lordosis (SL) in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF); however, their advantages over static cages remain controversial. This study compared the early radiological and perioperative outcomes of a boomerang-shaped expandable cage and conventional static cages in single-level MIS-TLIF. This retrospective observational study included 91 consecutive patients who underwent primary single-level MIS-TLIF for degenerative lumbar disease between September 2022 and October 2025. Patients were divided into an expandable cage group (E-group, n=47) and a static cage group (S-group, n=44). Lumbar lordosis (LL), SL, and intervertebral DH were evaluated preoperatively and at 3 months postoperatively. Operative time, blood loss, early cage subsidence, and endplate breach were also assessed. Because preoperative DH differed between the groups, an additional multiple linear regression analysis was performed with postoperative DH as the dependent variable and cage group, preoperative DH, and their interaction as predictors. SL increased significantly in the E-group but not in the S-group. The increase was greater in the E-group (+2.14°±4.15° vs. +0.12°±2.31°, P=0.005). DH increased significantly in both groups, with a greater increase in the E-group (+2.83±1.68 vs. +2.09±0.90 mm, P=0.01). Preoperative DH was greater in the E-group (8.1±1.8 vs. 7.1±2.2 mm, P=0.03), and a significant group-by-preoperative DH interaction was observed (P<0.001). At the overall mean preoperative DH of 7.607 mm, postoperative DH was estimated to be 1.14 mm greater in the E-group than in the S-group [95% confidence interval (CI): 0.72-1.57 mm; P<0.001]. The change in LL did not differ significantly between groups (+1.10°±6.39° vs. -0.32°±4.78°, P=0.23). Operative time was not significantly different (81.9±14.6 vs. 77.4±11.2 min, P=0.11), whereas median blood loss was greater in the E-group [150 (IQR, 100-220) vs. 60 (IQR, 48.8-100) mL, P<0.001]. Early cage subsidence occurred in 4 of 47 (8.5%) and 8 of 44 patients (18.2%), respectively (P=0.22), and no endplate breach was identified in either group. Use of the boomerang-shaped expandable cage was associated with greater early restoration of SL and DH than the paired static cage strategy. However, the absolute radiological differences were modest, global LL correction did not differ, and intraoperative blood loss was greater. The clinical significance of these early radiological differences remains uncertain in the absence of validated patient-reported outcome measures.
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BibTeX
@article{yoshioka2026early,
title = {{Early radiological and perioperative outcomes of a boomerang-shaped expandable cage versus static cages in single-level minimally invasive transforaminal lumbar interbody fusion.}},
author = {Atsushi Yoshioka and Yasuhiro Yamamoto and Mikihiro Kondo and Takashi Hasegawa and Koichi Muramatsu and Kurenai Hachiya and Nobuyuki Fujita and Yudo Hachiya},
journal = {Journal of spine surgery (Hong Kong)},
year = {2026},
month = sep,
doi = {10.21037/jss-2026-0208},
url = {https://europepmc.org/article/MED/42996602},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Early radiological and perioperative outcomes of a boomerang-shaped expandable cage versus static cages in single-level minimally invasive transforaminal lumbar interbody fusion.
AU - Atsushi Yoshioka
AU - Yasuhiro Yamamoto
AU - Mikihiro Kondo
AU - Takashi Hasegawa
AU - Koichi Muramatsu
AU - Kurenai Hachiya
AU - Nobuyuki Fujita
AU - Yudo Hachiya
PY - 2026
DA - 2026/09/29
JO - Journal of spine surgery (Hong Kong)
DO - 10.21037/jss-2026-0208
UR - https://europepmc.org/article/MED/42996602
AB - Expandable cages have been reported to improve intervertebral disc height (DH) and segmental lordosis (SL) in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF); however, their advantages over static cages remain controversial. This study compared the early radiological and perioperative outcomes of a boomerang-shaped expandable cage and conventional static cages in single-level MIS-TLIF. This retrospective observational study included 91 consecutive patients who underwent primary single-level MIS-TLIF for degenerative lumbar disease between September 2022 and October 2025. Patients were divided into an expandable cage group (E-group, n=47) and a static cage group (S-group, n=44). Lumbar lordosis (LL), SL, and intervertebral DH were evaluated preoperatively and at 3 months postoperatively. Operative time, blood loss, early cage subsidence, and endplate breach were also assessed. Because preoperative DH differed between the groups, an additional multiple linear regression analysis was performed with postoperative DH as the dependent variable and cage group, preoperative DH, and their interaction as predictors. SL increased significantly in the E-group but not in the S-group. The increase was greater in the E-group (+2.14°±4.15° vs. +0.12°±2.31°, P=0.005). DH increased significantly in both groups, with a greater increase in the E-group (+2.83±1.68 vs. +2.09±0.90 mm, P=0.01). Preoperative DH was greater in the E-group (8.1±1.8 vs. 7.1±2.2 mm, P=0.03), and a significant group-by-preoperative DH interaction was observed (P<0.001). At the overall mean preoperative DH of 7.607 mm, postoperative DH was estimated to be 1.14 mm greater in the E-group than in the S-group [95% confidence interval (CI): 0.72-1.57 mm; P<0.001]. The change in LL did not differ significantly between groups (+1.10°±6.39° vs. -0.32°±4.78°, P=0.23). Operative time was not significantly different (81.9±14.6 vs. 77.4±11.2 min, P=0.11), whereas median blood loss was greater in the E-group [150 (IQR, 100-220) vs. 60 (IQR, 48.8-100) mL, P<0.001]. Early cage subsidence occurred in 4 of 47 (8.5%) and 8 of 44 patients (18.2%), respectively (P=0.22), and no endplate breach was identified in either group. Use of the boomerang-shaped expandable cage was associated with greater early restoration of SL and DH than the paired static cage strategy. However, the absolute radiological differences were modest, global LL correction did not differ, and intraoperative blood loss was greater. The clinical significance of these early radiological differences remains uncertain in the absence of validated patient-reported outcome measures.
SN - 2414-469X
SN - 2414-4630
ER -