Paravertebral Muscular Neurophysiological Function as an Independent Outcome Predictor of Recurring Herniation/Low Back Pain after Radiofrequency Ablation: A Prospective Follow‐Up and Case‐Control Study Based on Surface Electromyography

Abstract

Objective Spinal endoscopy radiofrequency is a minimally invasive technique for lumbar disc herniation (LDH) and low back pain (LBP). However, recurring LDH/LBP following spinal endoscopy radiofrequency is a significant problem. Paravertebral musculature plays a crucial role in spine stability and motor function, and the purpose of the present study was to identify whether patients’ baseline lumbar muscular electrophysiological function could be a predictor of recurring LDH/LBP. Methods This was a prospective follow‐up and case‐control study focusing on elderly patients with LDH who were treated in our department between January 1, 2018, and October 31, 2021. The end of follow‐up was recurring LBP, recurring LDH, death, missing to follow‐up or 2 years postoperation. The surface electromyography test was performed before the endoscopy C‐arm radiofrequency (ECRF) operation to detect the flexion–relaxation ratio (FRR) of the lumbar multifidus (FRRLM) and the longissimus erector spinae (FRRES), and the other baseline parameters included the general characteristics, the visual analogue scale, the Japanese Orthopaedic Association score, and the Oswestry Disability Index. Intergroup comparisons were performed by independent t‐test and χ2‐test, and further binary logistic regression analysis was performed. Results Fifty‐four patients completed the 2‐year follow‐up and were retrospectively divided into a recurring LDH/LBP group (Group R) (n = 21) and a no recurring group (Group N) (n = 33) according to their clinical outcomes. FRRLM and FRRES in Group N were much higher than those in Group R (p < 0.001, p = 0.009). Logistic regression analysis showed that only the FRRLM (odds ratio [OR] = 0.123, p = 0.011) and FRRES (OR = 0.115, p = 0.036) were independent factors associated with the ECRF outcome. Conclusions Lumbar disc herniation patients’ baseline FRRLM and FRRES are independent outcome predictors of recurring LDH/LBP after ECRF. For every unit increase in baseline FRRLM, the risk of recurring LDH/LBP is decreased by 87.7%, and for every unit increase in baseline FRRES, the risk of recurring LDH/LBP is decreased by 88.5%.

Keywords

• Flexion–Relaxation Ratio
• Outcome Predictor
• Paravertebral Musculature Function
• Spinal Endoscopy Radiofrequency
• Surface Electromyography (sEMG)