Abstract: Objective To investigate different ways of annulus fibrosus repair after transforaminal endoscopic nucleus pulposectomy in the treatment of lumbar disc herniation and clinical outcomes. 
Methods In total, 128 patients with lumbar disc herniation were treated with minimally invasive transforaminal endoscopic nucleus pulposectomy via the lateral-posterior approach. All patients underwent transforaminal endoscopic nucleus pulposectomy (using TESSYS technology). Thirty-two patients in the control group were directly withdrawn from the working channel without any routine treatment after simple removal of the nucleus pulposus. The experimental group was divided into three groups according to different repair methods of annulus fibrosus repair before surgery: the radiofrequency group (n=32) was treated with bipolar radiofrequency to ablate and shrink the ruptured fibrous ring; 32 patients in the protein glue group were treated with medical biological protein glue to locally seal the damaged area of the fibrous ring before the end of the surgery. Another 32 patients in the artificial dura mater group were treated with artificial dura mater slices (5 mm×5 mm) placed at the damaged area of the fibrous ring. Visual analog scale (VAS) pain score, Oswestry disability index (ODI), MRI T2 weighted image signal intensity, and nucleus pulposus removal volume (cm3) lumbar curvature index (LCI) and intervertebral space height were compared in the four groups. 
Results The incisions of all postoperative patients healed in stage I, and there were no early postoperative complications. All patients were followed up for 10-22 months, with an average of 18 months. During the follow-up period, the patient had no typical symptoms of postoperative nucleus pulposus protrusion. Postoperative follow-up did not show any adverse reactions of two absorbable implant materials, biological protein glue and artificial dura mater. During the follow-up period, there were no complications such as intervertebral space infection, cerebrospinal fluid leakage, and epidural hematoma. There was no statistically significant difference in preoperative ODI score, lower back VAS pain score, and lower limb VAS pain score among groups (P＞0.05). At the 2-year follow-up after surgery, all three indicators in each group showed significant improvement compared with those before surgery (P＜0.05). There was no significant difference among four groups (P＞0.05). There was no significant difference in signal intensity of T2 weighted MRI images of intervertebral discs among the groups before surgery (P＞0.05). There was a significant difference between the 2-year follow-up after surgery and before surgery (P＜0.05). There was a significant difference in signal intensity among four groups of intervertebral disc MRI T2 weighted images at 2-year follow-up (P＜0.05). Before surgery, there was no significant difference in LCI and intervertebral space height among four groups (P＞0.05). And the 2-year follow-up after surgery, the LCI and intervertebral space height of the four groups were all lower than those before surgery (P＜0.05), and there was no significant difference in LCI among four groups (P＞0.05). The intervertebral space height of the radiofrequency group, protein glue group, and artificial dura mater group was higher than that of the control group (P＜0.05). The volume of nucleus pulposus removal during surgery in the radiofrequency group, protein glue group, and artificial dura mater group was (4.1 ± 1.8) cm3, (4.2±1.4) cm3, and (4.0 ± 1.6) cm3, respectively, which was greater than the volume of nucleus pulposus removal in the control group ［(3.9±1.9) cm3］, and the difference was significant (P＜0.05). At 3 and 6 months after surgery, the spinal motor function measurements in the frequency group, protein glue group, and artificial dura mater group were better than those in the control group (P＜0.05). 
Conclusion Application of transforaminal endoscopic nucleus pulposectomy and annulus fibrosus repair in the treatment of lumbar disc herniation have great clinical outcomes. More to the point, longer-term results will need further follow-up observation. 

Key words: intervertebral disc displacement, nucleus pulposectomy, transforaminal endoscope