Degree of paraspinal muscle fat infiltration predicts non-infectious poor wound healing following lumbar surgery

• Preoperative paraspinal muscle fat infiltration percentage, measured via MRI, is an independent risk factor for non-infectious poor wound healing after traditional open posterior lumbar surgery. • Fat infiltration percentages in the multifidus and erector spinae muscles have high predictive value (AUC > 0.7) for identifying patients at risk of poor wound healing. • Osteoporosis is associated with increased fat infiltration in the L4 multifidus muscle, suggesting a link between bone health and muscle degeneration. • The study provides a quantitative threshold (L4 multifidus >16.31%, L4 erector spinae >8.945%) for clinically significant fat infiltration that increases the risk of poor healing.