Cage migration in multilevel stand-alone lateral lumbar interbody fusion: incidence and clinical correlations.

OBJECTIVE

The objective of this study was to investigate the incidence and postoperative clinical outcomes of lateral interbody cage migration (LCM) in patients undergoing multilevel stand-alone lateral lumbar interbody fusion (LLIF) compared with an aged-matched cohort undergoing LLIF with posterior pedicle screw instrumentation.

METHODS

A retrospective review was conducted of the medical records of patients who underwent multilevel LLIF between 2017 and 2024 at a single institution and had ≥ 1 year of follow-up and postoperative radiographic follow-up. Demographic, operative, and postoperative data were collected and analyzed. Statistical analyses were performed using the chi-square test and independent-sample t-tests to assess the differences between continuous and categorical variables comparing both cohorts (stand-alone vs posterior instrumentation). Age-matched cohort analysis was performed, evaluating the distribution of both cohorts using a frequency matching analysis with the posterior instrumentation cohort as the control group and confirming equal distribution with the chi-square statistical test. Confounding factors were evaluated using logistic regression analyses.

RESULTS

Eighty-seven patients met the inclusion criteria (43 in the stand-alone cohort, 44 in the posterior instrumentation cohort). For the stand-alone cohort, the mean (SD) age was 70.2 (8.2) years (30 [70%] males, 13 [30%] females). For the posterior instrumentation cohort, the mean (SD) age was 69.6 (7.1) years (28 [64%] females, 16 [36%] males). In the stand-alone cohort, 43 surgeries were performed involving the following 110 levels: L1-2 (n = 9), L2-3 (n = 36), L3-4 (n = 42), L4-5 (n = 23), and L5-S1 (n = 0). In the posterior instrumentation cohort, 44 surgeries were performed involving the following 112 levels: L1-2 (n = 6), L2-3 (n = 21), L3-4 (n = 44), L4-5 (n = 41), and L5-S1 (n = 0). The incidence of LCM was 7% in the stand-alone cohort and 5% in the posterior instrumentation cohort, with no statistically significant differences observed between the 2 cohorts. There were no statistically significant confounding factors. Patient-related outcomes, including Oswestry Disability Index and visual analog scale scores, showed postoperative improvement in both cohorts.

CONCLUSIONS

The difference in the incidence of LCM between the stand-alone cohort and the posterior instrumentation cohort was not statistically significant. Although posterior instrumentation has traditionally been used to enhance construct stability, multilevel stand-alone LLIF can be a safe procedure. Prospective study designs are warranted to validate these findings and elucidate factors contributing to cage migration in multilevel stand-alone LLIF versus LLIF with posterior pedicle screw instrumentation procedures.