Body Mass Index as a Risk Factor for Recurrence and Frequency of Re-surgery after Lumbar Spine Surgery.

Abstract

Obesity is linked to degenerative spinal disorders, but its effect on recurrence and re-surgery after lumbar spine surgery remains unclear. Elevated body mass index (BMI) may influence outcomes through biomechanical stress and metabolic inflammation. To evaluate the association between BMI and the risk of recurrence and re-surgery following lumbar discectomy. This retrospective cohort study included 286 adult patients (171 males, 115 females; mean age 41.9 ± 11.2 years) who underwent single-level lumbar discectomy for degenerative disc disease at Al-Ahrar Teaching Hospital and Zagazig University Hospitals, Egypt, between January 2015 and October 2025. Patients with multilevel disease, spinal instability, prior lumbar surgery, or incomplete follow-up were excluded. BMI was recorded at surgery and follow-up. Recurrence was defined clinically and radiologically, confirmed by re-surgery. Logistic regression and Kaplan-Meier analysis assessed associations between BMI and recurrence. Recurrence occurred in 28 patients (9.8%). Patients with recurrence had higher BMI at initial surgery compared with those without recurrence (25.8 ± 2.8 vs. 22.9 ± 2.0 kg/m²; P < 0.001). Overweight and obese patients (BMI ≥25 kg/m²) accounted for 64.3% of recurrences. Each 1 kg/m² increase in BMI increased recurrence odds by 38% (OR = 1.38; 95% CI 1.17-1.63; P < 0.001). Kaplan-Meier analysis showed shorter recurrence-free survival in patients with elevated BMI (P < 0.001). Modic changes were the strongest independent risk factor. Elevated BMI is significantly associated with increased recurrence and reoperation after lumbar discectomy. Preoperative BMI optimization may reduce the risk of re-surgery and improve postoperative outcomes.