Expandable cages increase the risk of intraoperative subside
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Expandable cages (EXP) are being more frequently utilized in transforaminal lumbar interbody fusions (TLIF). EXP were designed to reduce complications related to neurological retraction, enable better lordosis restoration, and improve ease of insertion, particularly in the advent of minimally invasive surgical (MIS) techniques, however they are exponentially more expensive than the nonexpandable (NE) alternative. A Study was conducted to investigate the clinical results of expandable cages in single level TLIF.

252 single level TLIFs from 2012 to 2018 were included. Patients more than 18 years of age who underwent single level TLIF with minimum 1 year follow-up were included.
Radiographic analysis included pelvic incidence-lumbar lordosis (PI-LL) mismatch, segmental lumbar lordosis (LL) mismatch, disc height restoration, and subsidence more than 2 mm. Statistical analysis included independent t tests and chi-square analysis. For nonparametric variables, Mann-Whitney U test and Spearman partial correlation were utilized. Multivariate regression was performed to assess relationships between surgical variables and recorded outcomes. For univariate analysis significance was set at Due to the multiple comparisons being made, significance for regressions was set utilizing Bonferroni correction.

252 TLIFs were included, with 152 NE and 100 EXP with no significant differences in demographics. Patients instrumented with EXP cages had a shorter length of stay and a lower estimated blood loss. There were significantly more MIS-TLIF cases and bone morphogenic protein (BMP) use in the EXP group (88% MIS). There were no significant differences between the EXP and NE groups in rates of radiculitis and neuropraxia.
In multivariate regression analysis, EXP were not associated with a difference in perioperative outcomes or complications. Radiographic analysis demonstrated that the EXP group had a lower PI-LL mismatch than the NE cage group at baseline and at 1 year follow-up, but change in regional and segmental alignment was not significantly different between groups. Multivariate regression demonstrated that EXP use was a risk factor for intraoperative subsidence.

Conclusively TLIFs utilizing EXP do not have significantly improved neurologic or radiographic outcomes compared with NE. EXP increase risk of intraoperative subsidence. These results question the value of the EXP given the higher cost.

Source: https://www.thespinejournalonline.com/article/S1529-9430(20)31077-9/fulltext