Bone cement distribution patterns influence cage subsidence after OLIF-AF-SEA in elderly patients with osteoporotic lumbar degeneration.

PURPOSE: To investigate the correlation between postoperative bone cement distribution patterns and the incidence of cage subsidence in elderly osteoporotic patients undergoing oblique lateral interbody fusion combined with anterolateral fixation and stress endplate augmentation (OLIF-AF-SEA).

METHODS

This retrospective study analyzed 86 osteoporotic patients aged ≥ 60 years who underwent single-level L4-5 OLIF-AF-SEA with a minimum postoperative follow-up of 24 months. Postoperative X-rays were used to classify bone cement distribution patterns, including coronal plane distribution (three-zone method), endplate contact (binary classification), and presence of intervertebral leakage. Cage subsidence was defined as a reduction in disc height of ≥ 2 mm. Statistical analyses included chi-square tests and univariate binary logistic regression.

RESULTS

Among the 86 patients, 16 (18.6%) experienced cage subsidence. Subsidence was significantly associated with unilateral or paramedian cement distribution in the coronal plane, lack of endplate contact, and the presence of intervertebral leakage (all p < 0.001). Logistic regression analysis identified non-bilateral distribution (L4: B = - 4.313; L5: B = - 5.273), absence of endplate contact (B = - 4.234), and intervertebral leakage (B = 3.446) as significant predictors of subsidence. No significant differences were found between the subsidence and non-subsidence groups in terms of age, sex, BMI, or bone quality parameters.

CONCLUSION

Postoperative bone cement distribution patterns may influence cage stability following OLIF-AF-SEA. Bilateral distribution, contact with both superior and inferior endplates, and absence of intervertebral leakage are closely associated with reduced risk of subsidence. These findings highlight the importance of standardized cement injection strategies and provide a theoretical foundation for improving surgical outcomes in elderly osteoporotic patients undergoing OLIF-AF-SEA.