Risk Scale to Guide Prophylactic Paraspinous Flap Closure in High-Risk Spine Surgery

Background: Wound failure after posterior spine surgery can lead to infection, hardware loss, and reoperation. Prophylactic paraspinous muscle flaps are used selectively, but criteria to select which patients benefit most have not been consistent. Methods: We conducted a retrospective cohort study (2011–2022) of complex posterior spine operations closed by plastic surgery at a single center. The exposure was prophylactic paraspinous flap at the index operation versus standard primary closure. The primary outcome was a plastic surgery–managed wound complication requiring clinical intervention or return to the operating room. Using only routine pre and intraoperative variables, we created a five factor bedside score (obesity; lumbar/sacral level; albumin 250 minutes; American Society of Anesthesiologists ASA class ≥3) and a parallel logistic model that excluded treatment to estimate baseline risk and support decision making. Results: Among 281 operations, 150/281 (53%) received prophylactic paraspinous closure. Plastic-surgery–managed wound complications occurred in 35/281 (12.5%). A simple baseline-risk model separated patients into Low, Intermediate, and High-risk groups with observed complication rates of 7.9%, 11.7%, and 23.2%, respectively. Model performance was modest (area under the ROC curve AUC 0.66; optimism-corrected AUC 0.56; Brier 0.106). In adjusted analyses, ASA ≥3 was associated with higher odds of a wound complication (adjusted OR 9.35; 95% CI, 1.20–73.02). In the High-risk (4–5 points) group of the five-factor score, prophylactic closure reduced reoperations from 20.0% (4/20) to 0% (0/27) (absolute risk reduction ARR 20%; number needed to treat NNT 5; p=0.027). No significant differences were seen in the lower-risk groups. Conclusion: A simple five factor score stratifies baseline wound risk after posterior spine surgery and identifies patients most likely to benefit from prophylactic paraspinous flap closure. Selective, preoperative use in high risk patients may reduce returns to the operating room.