Stratified Classification of Intraoperative Endplate Injury during Oblique Lumbar Interbody Fusion: Incidence and its Influence on Cage Subsidence

Introduction: Intraoperative endplate injury (IOEPI) during oblique lumbar interbody fusion (OLIF) was confirmed through immediate postoperative computed tomography (CT) and the risk factors of IOEPI were analyzed.

Aims/

Objectives: The purpose of this study was to confirm whether IOEPI affects the development of postoperative cage subsidence.

Methods: Patients who could be followed up for more than 6 months after OLIF surgery were retrospectively collected. Among them, patients who underwent lumbar spine CT during postoperative hospitalization were identified and analyzed for IOEPI occurrence. According to the severity of IOEPI, it was stratified into scalloping / discontinuation / fracture or cage incarceration type. Demographic data were compared according to the presence or absence of IOEPI, and the correlation between occurrence of IOEPI and cage subsidence identified during the postoperative follow-up period was analyzed. Cage subsidence was classified into early and late subsidence based on the first month after surgery.

Results: A total of 32 patients, 56 levels in 45 patients, and 72 levels of OLIF surgery were confirmed for IOEPI through immediate postoperative CT. Among them, 18 patients, and 35 levels of IOEPI were confirmed. The mean age of the group with IOEPI was relatively higher (76.5 ± 6.0 vs. 69.7 ± 9.1, p = 0.001). The subtype of IOEPI was scalloping / discontinuation / fracture or cage incarceration in 4/4/10 patients and 11/6/18 levels, respectively. The incidence of IOEPI showed a statistically significant correlation with the appearance of the early cage subsidence (p = 0.001). Scalloping type IOEPI showed a significant relationship with the occurrence of late cage subsidence (p = 0.045), and appeared at an average of 2.92 months after surgery. The incidence of fracture or cage incarceration type IOEPI was associated with spondylolisthesis (p = 0.001) and showed a statistically significant relationship with the appearance of early cage subsidence.

Conclusions: IOEPI confirmed on immediate postoperative CT was confirmed in about 56% of patients who underwent OLIF. In the surgical treatment of the lumbar spondylolisthesis segment through OLIF, careful attention should be paid to the occurrence of endplate fracture or cage incarceration to prevent the occurrence of subsequent early subsidence.