In the interlaminar group, an intraoperative epineurium injury occurred (3.3%), without cerebrospinal fluid fistula. No limb paralysis or postoperative infections were observed after surgery. One case suffered recurrence 10 weeks after surgery, resulting in a total recurrence rate of 3.3% during the 18-month follow-up. 29 cases (96.7%) return to work three months after surgery. The recurrence case was treated by minimally-invasive transforaminal lumbar interbody fusion.
In the transforaminal group, an intraoperative epineurium injury occurred (3.3%), without cerebrospinal fluid fistula. No limb paralysis or postoperative infections were observed after surgery. No visceral organ or vascular injury occurred. 30 cases (100%) return to work three months after surgery. In addition, no recurrence occurred during the 18-month follow-up (0%).
Previous studies on PELD via the interlaminar and transforaminal approaches have reported the mean operative times ranging 22.0 to 71.3 minutes and 22.0 to 86.0 minutes, respectively.[15,18,22–28] The mean operative times of both groups in the present study were consistent with those in the literature. Furthermore, the mean operative time of the interlaminar group was significantly less than that of the transforaminal group.
During traditional PELD using YESS and TESSYS techniques, preoperative localization of the puncture target, punching procedures, and foraminoplasty are performed under fluoroscopy, resulting in too much radiation exposure. Previous studies have reported the mean fluoroscopy times during interlaminar and transforaminal endoscopic discectomy of 0.6 to 5.5 seconds and 6.5 to 39.4 seconds, respectively.[12,15,26,29,30] In this study, preoperative and intraoperative fluoroscopy was only applied to locate the puncture target and working cannula. full-endoscopic visualization technique provides an opportunity to establish the working cannula under visual control, with less radiation exposure and a shorter fluoroscopy time compared to those in traditional PELD.[15,29,30] Furthermore, the mean fluoroscopy time in the interlaminar group was significantly shorter than that in the transforaminal group.
Due to extensive exposure of the intervertebral disc and nerve root, scarring of the epidural space has been observed postoperatively after conventional surgeries.[31–35] Although only 10% become clinically symptomatic, epidural adhesions have been confirmed on MRI images in many cases. However, full-endoscopic visualization technique via the interlaminar approach preserves most of the ligamentum flavum, and reduces the formation of epidural scar adhesion. Furthermore, no scarring in the access area, and only slight scarring in the spinal canal has been observed in cases of recurrent herniation. Full-endoscopic visualization technique via the transforaminal approach avoids the irritation of the spinal canal and the formation of epidural scar adhesion.
Although cases of recurrent disc herniation were excluded from the present study, full-endoscopic visualization technique via both interlaminar and transforaminal approaches is possible for revision surgeries. Furthermore, full-endoscopic visualization technique via the transforaminal approach can be used to perform discectomy with unscarred virgin tissue to avoid the risk of iatrogenic neural injury and dural tears after surgeries via the interlaminar approach.[12,14,17] Full-endoscopic visualization technique via the interlaminar approach can also be used to perform discectomy with unscarred virgin tissue in cases treated by surgeries via the transforaminal approach.
The present study was also of some limitations, as it is a retrospective, non-randomized controlled cohort study with a small sample size and short follow-up period. It may be difficult to compare the true disc herniation recurrence rate after discectomy in such a short follow-up period. The senior author's personal experience in full-endoscopic visualization technique via both approaches may also bias the results. Further prospective, randomized, controlled studies, as well as more comparative studies, with larger sample sizes and longer follow-up periods, should be conducted to assess the clinical outcomes.
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