1.1 Study design
We retrospectively reviewed the medical records of 230 patients, who treated at the Department of Pain Management, YangLing Demonstration Zone Hospital between January 2014 and December 2016. This study was approved by the clinical research ethics committee of YangLing Demonstration Zone Hospital (No. 2016-021). This study followed the Good Clinical Practice guidelines and the guidelines of the Helsinki Declaration. The study included 110 cases received TFESI (Group T) and 120 cases received TFESI combined with RF (Group TR).
Patients (aged 21~70 years old, BMI 16~38 and ASAⅠ~Ⅲ) undergoing TFESI combined with RF or TFESI operation as LDH were screened in this study. All patients presented who refused open surgery with lower back pain with sciatica and were ineffective after 3 months of adequately conservative treatment. The patient's signs and symptoms are caused by herniated discs, which was confirmed by MRI and CT. All patients were recorded CTF-classification of LDH. The following patients were excluded: multi-segmental disc herniation, sequestration type disc herniation，cauda equina syndrome, lumbar spinal stenosis, spinal metastatic disease, lumbar spondylolisthesis, psychosis, uncorrectable bleeding quality, patients who lost to follow-up, and previous lumbar surgery.
Guided by C-arm fluoroscopy, the patient is placed in the prone position with U-shaped pillows under the chest and both ilia so that the abdomen is suspended. The injection site was sterilized with antiseptic fluid and draped with surgical towels.
In the TFESI procedure, a local anesthetic (3 mL of 0.5% lidocaine) is injected into the skin and subcutaneous tissue at the injection site. A 0.35-inch 18 cm needle is advanced in the area below the pedicle. As the epidural space is approached, anteroposterior and lateral view will be taken to confirm the needle position. Use 0.5 mL contrast medium to check whether the needle is in the epidural space. 3 mL mixture of corticosteroids and anesthetics (80 mg methylprednisolone, 5 mL 2% lidocaine and 5 mL 1% ropivacaine) were injected (Figure 1).
In the RF procedure, a puncture needle using a radio frequency probe is used to pierce the protrusion. According to the preoperative physical examination and imaging examination, the responsible target position of the intervertebral disc was determined. 6-14cm was opened beside the posterior midline. The puncture was carried out through the safety triangle with an included angle of 20-40 at coronal position to the herniated part of the intervertebral disc. After confirming the position of the guide needle with the anteroposterior and lateral view, we remove the probe, use or not 1 mL contrast medium to check whether the needle is in the disc, then advance the catheter rod through the guide needle to the center of the protruding portion. Radio frequency treatment was performed using a radio frequency temperature-controlled thermocouple (XJ-08; Xi'an Sterilization Equipment Manufacturing Co., Ltd.; Xi'an). The electrodes are inserted into a puncture needle, sensory and motor responses during RF neurotomy procedure might be used (albeit not obligatorily) to confirm the close proximity of targeted (and non-targeted) nerves to RF electrodes. Thermo coagulation was applied at 60℃, 70℃, and 80℃for 60s each, and 90℃ for 100s. (Figure 2)
Gender, age, BMI, operating time, and hospitalization time were evaluated and recorded. Follow-up were conducted preoperatively, and at 1, 3, 6, 12 and 24 months postoperatively. During the individual interviews, we collected information from the patients regarding side effects, discomfort, and recurrence. Assessments were conducted using the visual analog scale (VAS), the Oswestry Disability Index (ODI)，andthe Global perceived effect (GPE). The VAS rates pain severity as a score from 0 to 10，0 indicates no pain and a score of 10 indicates the most severe pain. The ODI assesses low back pain-related disability: the higher the score, the more severe the disability. The Global perceived effect (GPE) scale is a 7-question scale that asks subjects to rate their condition after receiving treatment, where 1=worst ever and 7=best ever. Success was defined as a score ≥5. Recurrent disc herniation is defined as a painless interval of at least 6 months after surgery, with herniated disc material at the same level and presenting the same symptoms as before surgery.
The primary outcomes were VAS and ODI pre-operation, 1, 3, 6, 12, and 24 months after the operation. The secondary outcomes included operation time, hospitalization time, complication and recurrence.
1.5 Statistical analysis
The statistical analysis was performed with SPSS 24.0 for Windows (SPSS, Inc., IBM). Measured data were tested for normal distribution and the homogeneity of variance. Numeric variables were expressed as Mean ± SD and analyzed by Independent-Samples T-test. Repeated measures of ANOVA (with Bonferroni confidence interval adjustment) tests were conducted for VAS and ODI. Categorical data were expressed by N (%) and were analyzed with the χ2 test. The value of p < 0.05 was taken as a significant difference.