Feasibility of the Non-Window-Type 3D-Printed Porous Titanium Cage in Posterior Lumbar Interbody Fusion: A Randomized Controlled Multicenter Trial

Dae-Woong Ham; Sang-Min Park; Youngbae B Kim; Dong-Gune Chang; Jae Jun Yang; Byung-Taek Kwon; Kwang-Sup Song

doi:10.2106/JBJS.23.01245

Feasibility of the Non-Window-Type 3D-Printed Porous Titanium Cage in Posterior Lumbar Interbody Fusion: A Randomized Controlled Multicenter Trial

J Bone Joint Surg Am. 2024 Sep 11. doi: 10.2106/JBJS.23.01245. Online ahead of print.

Authors

Dae-Woong Ham¹, Sang-Min Park², Youngbae B Kim³, Dong-Gune Chang⁴, Jae Jun Yang⁵, Byung-Taek Kwon⁶, Kwang-Sup Song¹

Affiliations

¹ Department of Orthopedic Surgery, Chung-Ang University Hospital, College of Medicine, Chung-Ang University, Seoul, Republic of Korea.
² Spine Center and Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnamsi, Republic of Korea.
³ Department of Orthopedic Surgery, VHS Medical Center, Seoul, Republic of Korea.
⁴ Spine Center and Department of Orthopedic Surgery, Inje University Sanggye Paik Hospital, College of Medicine, Inje University, Seoul, Republic of Korea.
⁵ Department of Orthopedic Surgery, Dongguk University Ilsan Hospital, Goyangsi, Republic of Korea.
⁶ Department of Orthopedic Surgery, Chung-Ang University Gwang Myeong Hospital, Gwangmyeongsi, Republic of Korea.

PMID: 39259778
DOI: 10.2106/JBJS.23.01245

Abstract

Background: Three-dimensionally printed titanium (3D-Ti) cages can be divided into 2 types: window-type cages, which have a void for bone graft, and non-window-type cages without a void. Few studies have investigated the necessity of a void for bone graft in fusion surgery. Therefore, the present study assessed the clinical and radiographic outcomes of window and non-window-type 3D-Ti cages in single-level posterior lumbar interbody fusion.

Methods: A total of 70 patients were randomly assigned to receive either a window or non-window cage; 61 patients (87%) completed final follow-up (32 from the window cage group, 29 from the non-window cage group). Radiographic outcomes, including fusion rates, subsidence, and intra-cage osseointegration patterns, were assessed. Intra-cage osseointegration was measured using the intra-cage bridging bone score for the window cage group and the surface osseointegration ratio score for the non-window cage group. Additionally, we looked for the presence of the trabecular bone remodeling (TBR) sign on computed tomography (CT) images.

Results: Of the 61 patients, 58 achieved interbody fusion, resulting in a 95.1% fusion rate. The fusion rate in the non-window cage group was comparable to, and not significantly different from, that in the window cage group (96.6% and 93.8%, p > 0.99). The subsidence rate showed no significant difference between the window and non-window cage groups (15.6% and 3.4%, respectively; p = 0.262). The intra-cage osseointegration scores showed a significant difference between the groups (p = 0.007), with the non-window cage group having a higher proportion of cases with a score of 4 compared with the window cage group. The TBR sign was observed in 87.9% of patients who achieved interbody fusion, with a higher rate in the non-window cage group across the entire cohort although the difference was not significant (89.7% versus 78.1%, p = 0.385).

Conclusions: Non-window-type 3D-Ti cages showed equivalent clinical outcomes compared with window-type cages and comparable interbody fusion rates. These results suggest that the potential advantages of 3D-Ti cages could be optimized in the absence of a void for bone graft by providing a larger contact surface for osseointegration.

Level of evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.