Implant Failure and Postoperative Complications After Stabilization Surgery for Spinal Metastases: A Single-Center Cohort Study,

Retrospective single-center cohort study. To evaluate associations between clinical, radiographic, and surgical factors and the risk of implant failure and postoperative complications following spinal stabilization for metastatic disease. Spinal metastases frequently cause pain, neurological deficits, and instability, often requiring surgical decompression and stabilization. As survival improves and the use of spinal instrumentation increases, understanding surgery-associated complication risks has become increasingly important. While postoperative complications in metastatic spine surgery have been reported across multiple cohorts, factors related to construct design and anchorage, including implant failure, wound infection, and postoperative bleeding, remain incompletely characterized. This study examines the incidence of these complications and their associated factors in patients undergoing stabilization for metastatic spinal disease. This retrospective study retrospectively analyzed 149 patients who underwent stabilization surgery for spinal metastases between 2010 and 2020. Instability was assessed using the Spinal Instability Neoplastic Score (SINS), functional status using the Karnofsky Performance Score, and neurological status using the Frankel classification. Associations between patient-, disease-, and surgery-related variables and postoperative outcomes were examined primarily using univariate logistic regression analyses. In univariate analyses, implant failure was significantly associated with instrumentation anchored in metastatically involved adjacent vertebrae (OR 9.22), reoperation for tumor progression (OR 8.25), preoperative Frankel Score E (OR 5.25), active smoking (OR 4.05), and postoperative wound infection (OR 4.88). Postoperative wound infection was associated with construct anchorage in metastatically involved adjacent vertebrae (OR 4.78) and a preoperative ACE-27 comorbidity score of 1 (OR 3.54). Postoperative bleeding or hematoma was associated with wound infection (OR 5.21), advanced age at surgery (OR 1.09), impaired preoperative mobility (OR 3.78), and lower postoperative Karnofsky Performance Score (OR 0.96). The Spinal Instability Neoplastic Score was associated with implant failure in univariate analysis but did not account for construct-end anchorage. Anchoring spinal constructs in vertebrae affected by metastases was consistently associated with increased risks of implant failure and postoperative infection following stabilization surgery. These findings highlight the mechanical and biological vulnerability of metastatic bone and suggest that, when feasible, fixation into structurally uninvolved vertebrae may reduce postoperative complications. • End anchorage in tumor-affected vertebrae raised failure 9-fold. • Wound infection and implant failure each raised the other's odds 5-fold. • While SINS remains valuable for assessing baseline instability, it did not retain an association with implant failure after adjustment, suggesting that radiographic instability alone may be insufficient to capture the mechanical challenges of metastatic fixation. • Extending construct ends into healthy bone may lower complication risk. This retrospective cohort study evaluated associations between clinical, radiographic, and surgical factors and postoperative complications following stabilization surgery for spinal metastases in 149 patients. Anchoring fixation constructs in metastatically involved vertebrae was consistently associated with higher risks of implant failure and wound infection. Tumor progression, active smoking, and functional status were also associated with implant failure. Postoperative bleeding was associated with wound infection, older age, and lower Karnofsky Performance Score, highlighting the multifactorial nature of complications in this population.