Incidence and risk factors of persistent low back pain following posterior decompression and instrumented fusion for lumbar disk herniation

INTRODUCTION: The aim of this study was to explore the incidence and risk factors of persistent low back pain (PLBP) following posterior decompression and instrumented fusion for lumbar disk herniation and to provide references in decision-making and surgical planning for both spinal surgeons and surgically treated patients. PATIENTS AND METHODS: By retrieving the medical records from January 2013 to December 2016, 221 patients were retrospectively reviewed. Patients were classified as having PLBP if numeric rating scale (NRS) scores were >50 at all postoperative follow-up time points (3 months, 6 months, and 12 months). According to the occurrence of PLBP, patients were divided into two groups: PLBP group and non (N)-PLBP group. To investigate risk values for PLBP, the following three categorized factors were analyzed statistically. Patient characteristics: age, gender, body mass index (BMI), preoperative low back pain, comorbidity, smoking, and drinking. Surgical variables: surgical strategy, surgical segment, the number of fusion levels, surgery time, blood loss, and size of incision. Radiographic parameters: preoperative lumbar lordosis (LL), correction of LL at immediate postoperation, Modic changes, and preoperative paraspinal muscle degeneration. RESULTS: PLBP was detected in 16 patients and were enrolled into the PLBP group. There was no difference between the two groups in age, gender, BMI, comorbidity, smoking, and drinking. The preoperative low back pain was more severe in the PLBP group than that in the N-PLBP group. There was no difference in surgery time, blood loss, surgical strategy, number of fusion levels, and the size of incision. Surgery segment at L(5)–S(1) was more prevalent in the PLBP group than that in the N-PLBP group, and there was no difference in preoperative LL, correction of LL, preoperative lumbar mobility, and Modic changes. The fatty infiltration rate (FIR) was larger in the PLBP group than that in the N-PLBP group. Multivariate logistic regression model revealed that preoperative low back pain (NRS > 35), surgery segment at L(5)–S(1), and FIR > 15% were independently associated with PLBP. CONCLUSION: The incidence of PLBP following posterior decompression and instrumented fusion for lumbar disk herniation is 7.2%, and the risk factors include preoperative low back pain, surgery segment at L(5)–S(1), and preoperative paraspinal muscle degeneration.