General Information
This research obtained the support of the Ethics Committee of our institution and informed consent of all patients. From August 2016 to December 2019, we collected 42 consecutive patients with L5-S1 CLDH treated with PEID and PETD in our hospital. These patients were divided into PEID (n = 24) and PETD (n = 18) groups according to the surgical methods. The inclusion criteria were as follows: 1) symptoms of pain and numbness of lower limbs; 2) L5-S1 CLDH confirmed by preoperative lumbar X-ray, computed tomography (CT) and magnetic resonance imaging (MRI); 3) failure of conservative treatment or no significant improvement in symptoms for greater than 3 months; and 4) the follow-up time was greater than 12 months. The exclusion criteria were as follows: 1) multisegmental lesions; 2) noncalcified lumbar disc herniation; 3) lumbar spinal stenosis, lumbar instability, lumbar tuberculosis, lumbar infection or spinal tumor. A percutaneous transforaminal endoscopic spine system (Joimax, Karlsruhe, Germany), tip-flexible bipolar radiofrequency system (Elliquence LLC, USA), ultrasonic osteotome (SMTP, China) and endoscopic instruments (MaxMorespine GmbH, Germany) were used.
Surgical Procedure
PEID. All patients were placed on the operating table in the prone position after general anesthesia. The surgical segment was identified by fluoroscopy on an X-ray machine. After marking the puncture site on the body surface, routine disinfection was performed. The puncture point was anesthetized with local infiltration of 0.5% lidocaine. The puncture needle was inserted in 1.0 cm beside the posterior midline. The needle position was confirmed by fluoroscopy of a C-arm X-ray machine. A 0.7-cm longitudinal incision was made at the skin mark. The skin, subcutaneous tissue and lumbodorsal fascia were incised in turn. The dilating tube was placed to the ligamentum flavum. The working cannula and endoscope were inserted along the dilating tube. After checking the operating system, the light source was connected, and the operation was performed under continuous saline irrigation. Under the endoscope, the ligamentum flavum was cut by scissors. After reaching the epidural space, the lateral dural sac and nerve root were exposed. The locations of the nerve root, dural sac and herniated disc were explored. The degree of calcification and size of the herniated disc were carefully confirmed. Under the endoscope, the calcified and herniated disc tissue was removed by an ultrasonic osteotome (SMTP, China), and the herniated free nucleus pulposus was removed using nucleus pulposus forceps. Under direct vision, no obvious compression of the nerve root and dural sac was observed. During the operation, bipolar radiofrequency ablation was used to adequately stop bleeding. After removing the working cannula, the incision was closed intradermally and covered with a sterile dressing. All patients underwent CT and MRI examinations before (Fig. 1A-D) and after (Fig. 1E-H) operation.
PETD. The patient was placed in a prone position after local anesthesia, and the responsible segment was identified by C-arm X-ray fluoroscopy. The level of responsible intervertebral space and the posterior midline line were marked. Routine disinfection and sheet laying were performed. The puncture site was set at 12 ~ 14 cm next to the posterior midline, and the puncture point was anesthetized with 0.5% lidocaine injection. The 18-G puncture needle was inserted in the marked puncture site, and the needle slid along the lateral aspect of the superior articular eminence and entered the spinal canal through the intervertebral foramen. It was confirmed that the puncture needle was located in the midline on the anterior radiograph and the posterior upper edge of the vertebral body on the lateral radiograph by fluoroscopy with a C-arm X-ray machine. After inserting the guide wire, a puncture needle was removed. The skin was cut to approximately 0.7 cm, and the expanding cannula was inserted gradually. Finally, the bevelled cannula was inserted along the dilatation tube. When the working channel was difficult to insert, part of the superior articular eminence could be ground off with a circular saw. The position of the working cannula was confirmed under fluoroscopy on a C-arm X-ray machine. The working cannula was flushed with 3000 ml of saline, and the calcified disc and herniated nucleus pulposus were removed with an ultrasonic osteotome (SMTP, China) and nucleus pulposus forceps under an endoscope. The working cannula was moved appropriately. The nerve roots and dural sac were moved. The nerve roots and dural sac were then explored for relaxation, and no protruding discs compressed the nerve roots and dural sac. The bipolar radiofrequency ablator was used to perform fibrous annuloplasty. Bleeding points were carefully explored and given adequate hemostasis. The nerve root and dural sac were confirmed to be free of compression, and no bleeding points were evident. The working cannula was removed. Then, the incision was sutured intradermally and covered with a sterile dressing. The CT and MRI examinations of all patients were done before (Fig. 2A-D) and after (Fig. 2E-H) operation.
Measures
Demographic characteristics, such as age, sex, body mass index (BMI) and follow-up time, were compared between the PEID and PETD groups. Surgical outcomes, such as operative time, intraoperative blood loss, intraoperative fluoroscopy times, postoperative hospital stay and complications, were compared between the two groups. Clinical outcomes indicators, including the preoperative and postoperative visual analog scale (VAS)[7] for leg pain, Oswestry disability index (ODI)[8], and modified MacNab criteria[9]at the last follow-up, were compared between the two groups.
Statistical Assessments
The SPSS 25.0 program (IBM Corporation, USA) was used for statistical analysis of all data. Comparisons between the two groups were analyzed by independent-sample t tests, whereas paired-samples t tests were used for intragroup comparison. Sex and complications were compared by chi-square tests. The modified MacNab criteria were compared by the Mann-Whitney U test. P < 0.05 indicates a statistically significant difference.