Early versus late construct failure in spine metastatic disease: implications for surgical strategy and oncologic outcome.

Purpose: This study aimed to identify variables that portend early construct failure requiring surgical revision in patients undergoing instrumented fusion for spine metastases.

Methods: A detailed retrospective chart review was performed. Demographic, surgical, and oncologic variables were collected and analyzed via independent samples t-testing, chi-square testing, and Kaplan-Meier method with log-rank testing. Significance was determined as p < 0.05.

Results: 482 spinal fusion operations for solid tumor metastases were performed between 2012 and 2022. Of these, 24 (5.0%) required revision surgery for construct failure. There were no major differences between the revision and non-revision patients in terms of several surgical characteristics. Thirteen (54.1%) were revised within 3 months of index surgery. These early construct failures were more likely to have functional neurological deficits at surgery (6/13 vs. 0/11 [p = 0.009]), longer constructs (mean 6.4±2.4 vs. 4.2 ± 1.4 levels [p = 0.015]), and cement-augmented pedicle screws (4/13 vs. 0/11 [p = 0.044)) compared to late construct failures (> 3 months after index surgery). Additionally, 17 symptomatic failures were identified, compared to 7 asymptomatic failures which were identified incidentally with routine follow-up imaging. All 7 asymptomatic construct failures occurred in the early revisions group [p = 0.004]. Revision surgery for early construct failure was associated with significantly reduced median overall survival compared to late failure (p = 0.010).

Conclusion: Construct failures in our cohort were not associated with any classical characteristics of patients undergoing revision spine surgery. Early revision (< 3 months) portends a reduction in overall survival when compared with late revisions, and early revised patients were more likely to have had more extensive surgery and poorer neurological status at the time of index cases.