Relationship between paraspinal sarcopenia and clinical outcomes of intervertebral disc degeneration patients following unilateral biportal endoscopy discectomy

This study aims to evaluate the prognostic significance of preoperative paraspinal sarcopenia (PS) on long-term clinical outcomes in patients with intervertebral disc degeneration (IDD) undergoing unilateral biportal endoscopy discectomy (UBED), and to identify independent risk factors of postoperative chronic low back pain. A retrospective cohort study was conducted on 148 IDD patients who underwent UBED, classified into sarcopenia (n = 65) and non-sarcopenia (n = 83) groups based on psoas muscle index (PMI) thresholds. Radiographic parameters, including PMI, erector spinae muscle index (EMI), multifidus muscle index (MMI), multifidus fat infiltration (MFI), erector spinae fat infiltration (EFI), and multifidus muscle density (MMD), were assessed via CT/MRI. Clinical outcomes were evaluated using the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) preoperatively and postoperatively at 1 month, 6 months, and final follow-up (≥ 12 months). Univariate and multivariate logistic regression analyses identified risk factors for chronic low back pain. The sarcopenia group exhibited significantly lower muscle indices (PMI, EMI, MMI; all P < 0.001) and higher fat infiltration (MFI, EFI; P < 0.05) compared to the non-sarcopenia group. While both groups demonstrated improvements in VAS and ODI scores postoperatively, the sarcopenia group had higher VAS (3.21 ± 0.92 vs. 2.75 ± 0.72, P < 0.001) and ODI (22.19 ± 4.37% vs. 19.08 ± 3.43%, P < 0.001) at final follow-up. Elevated BMI, lower BMD, reduced muscle indices (PMI, EMI, MMI), and severe MFI were significant predictors of chronic low back pain (P < 0.05). PS is a modifiable risk factor for postoperative chronic low back pain after UBED. Preoperative identification of high-risk patients and targeted interventions to improve muscle function may enhance clinical outcomes. These findings underscore the importance of integrating muscle health assessments into spine care pathways.