Minimally Invasive Stabilization Versus Open Surgery for Spinal Metastases: A Retrospective Study Utilizing Propensity Score Matching and Weighting Sensitivity Analyses

Background: Minimally invasive spinal stabilization (MISS) is increasingly used in metastatic spine surgery, but comparative evidence vs. open posterior stabilization (OPEN) remains limited. We compared perioperative outcomes, focusing on wound-related morbidity. Methods: This retrospective single-center cohort included 71 patients undergoing posterior stabilization for spinal metastases (MISS n = 45; OPEN n = 26). Wound-healing disorder was the primary endpoint. Groups were compared using nonparametric exact tests; adjusted and propensity score analyses were performed to assess robustness. Results: Baseline SINS, operated segment, and instrumented levels were comparable. BMI was higher in MISS (25.8 [24.0–29.7] vs. 22.1 [20.0–24.9] kg/m2; p = 0.001), and urgent admissions were more frequent in OPEN (42.3% vs. 11.1%; p = 0.006). Wound-healing disorders occurred in 6.7% (3/45) of the MISS group vs. 30.8% (8/26) of the OPEN group. (p = 0.014; crude RR 4.62, 95% CI 1.34–15.88). After adjustment for admission type, BMI, and ECOG (n = 65), the association was attenuated (adjusted RR 1.80, 95% CI 0.24–13.68; p = 0.572). SSI occurred in 1/45 (2.2%) MISS vs. 5/26 (19.2%) OPEN (p = 0.022). Estimated blood loss was similar between groups (MISS: 500 [350–800] vs. OPEN: 600 [500–700] mL; p = 0.357). The median length of stay was shorter in the MISS group, though this did not reach statistical significance. In trimmed IPTW (64 complete cases), OPEN remained associated with higher weighted risk (RR 1.91, 95% CI 0.42–8.65; p = 0.403). Conclusions: OPEN surgery was associated with higher unadjusted wound-related morbidity than MISS, while blood loss did not differ between approaches. Length of stay tended to be shorter after MISS, but analyses were underpowered.