Clinical Outcomes of Percutaneous Transforaminal Endoscopic Discectomy Versus Fenestration Discectomy in Patients with Lumbar Disc Herniation
DING Zhen-mei, TAO Yong-qing*
Department of Orthopaedics, Nantong Fourth People's Hospital, Nantong, Jiangsu, 226005, China
*Corresponding Author:TAO Yong-qing, E-mail: taotao39@163.com
Abstract

Background: Fenestration discectomy (FD) is a common treatment method for lumber disc herniation (LDH), with good effects obtained. Nevertheless, it also causes many complications, such as lumbar instability, lumbago and back pain. Percutaneous endoscopic lumbar discectomy (PTED) is a new minimally invasive treatment available for LDH with conservative therapy failure. At present, this technique has been carried out in China. The purpose of this study was to conduct a randomized prospective trial to compare the surgical outcomes of PTED and FD, explore the clinical application value of PTED, and discuss the operative manipulated skills of PTED.Methods: Totally 100 patients with LDH were enrolled from March 2014 to December 2015 and randomly divided into PTED group and FD group, 50 cases in each group. FD group received FD including epidural anesthesia, unilateral fenestration decompression, removal of nucleus pulposus, and nerve root decompression and release, while FTED group received PTED including local anesthesia, endoscopic removal of herniated nucleus pulposus and nerve root decompression and release. Both groups were followed up postoperatively. The duration of operation, incision length, postoperative bed-rest and hospital stay were compared between two groups, and the visual analogue scale (VAS), Oswestry disability index (ODI), and therapeutic effects at the final follow-up time were recorded and compared between 2 groups.Results: All patients completed the operation successfully. The surgical duration was similar between two groups ( P>0.05). PTED group showed a less incision length and shorter postoperative bed-rest time and hospital stay than FD group ( P<0.01). The VAS and ODI scores showed a significant decrease in both groups postoperatively when compared with operation before ( P<0.05), but with no significant difference between two groups ( P>0.05). Moreover, the excellent and good rate was higher in PTED group thanin FD group, with no statistical difference between them ((90.0% vs. 90.0%, Z=-1.113, P=0.266)).Conclusion: Both FD and PTED are effective in the treatment of LDH. However, PTED is superior to FD due to smaller incision, shorter postoperative hospital stay, less affect on spinal instability and faster recovery, thus the long-term outcomes deserve to be further studied.

Key words: Percutaneous transforaminal endoscopic discectomy; Fenestration discectomy; Lumbar disc herniation; Minimal invasive surgery
Introduction

Lumbar disc herniation (LDH) is a common disease in spine surgery, and a major cause of back pain and sciatica [1]. In conventional open lumbar discectomy, posterior approach to resect partial vertebral plate and facet joint has been adopted for full exposure of intervertebral foramen and disc, with definite effects obtained. However, it can also lead to destruction of unilateral facet joint, thus aggravating lumbar instability and degeneration. Additionally, this surgery has large operative wound and long postoperative recovery time[2]. In the 1880s, Parviz Kambin and Hijikata first adopted working pipe to conduct discectomy. Until 1996, US Food and Drug Administration (FDA) had approved the use of spinal endoscopic system, and spinal endoscope technologies have been gradually carried out in the treatment of lumbar disc herniation (LDH) [3]. Fenestration discectomy (FD) is a common treatment method for LDH, with good effects obtained. However, paravertebral muscle stripping, long-time traction during operation and excessive removal of posterior lumbar structure can trigger complications like lumbar instability, lumbago and back pain [4, 5, 6]. Percutaneous endoscopic lumbar discectomy (PTED) is a new minimally invasive treatment method for patients with LDH with conservative therapy failure. At present, this technique has been carried out in China [7, 8]. The purpose of this study was to conduct a randomized prospective trial to compare the surgical outcomes of PTED and FD, explore the clinical application value of PTED, and discuss the operative manipulated skills of PTED.

Materials and Methods
General data

Ethical committee approval was obtained from The Second People’ s Hospital of Changzhou, and patients were enrolled immediately after they signed the informed consent forms. Inclusion criteria: (1) preoperative conventional examinations including adem-positionvertebra lumbalis X-rays, dynamic radiographs, magnetic resonance imaging (MRI), computerized tomography (CT); (2) patients with recurrent LDH; (3) lumbago accompanied by radioactive pain of unilateral lower limb which showed positive straight leg raising test, decreased muscular strength, skin numbness and the corresponding tendon hyporeflexia; (4) patients after invalid conservative treatment for 3 months; (5) imageological examination showing single-segmental unilateral LDH without accompany of lateral recessus stenosis, and thickening and calcification of posterior longitudinal ligament andligamentum flavum. Exclusion criteria: (1) patients with surgical contraindication; (2) patients with multi-segmental or bilateral LDH; (3) patients with LDH infectious lesions (discitis and tuberculosis of lumbar spine); (4) patients with the head of intervertebral disc dissociating and protruding upwards; (5) patients with severe scoliosis, spondylolysis, lumbar spondylolisthesis, lumber instability, lumbar vertebrae fracture, etc.; (6) patients in pregnant period or those with mental disease, and the elderly with poor tolerance to operation.

A total of 100 patients with single-segmental unilateral LDH admitted in our hospital from March 2014 to December 2015 were enrolled and randomly divided into two groups: PTED group and FD group, 50 cases in each group. The baseline data were shown in Table 1. There was insignificant difference between two groups in baseline data, such as gender, age, distribution of segmental lesions, and course of disease (P> 0.05), with comparability.

Table 1 The Baseline Data in two Groups ( x̅± s)
Methods

FD group: FD was performed under epidural anesthesia. Patients were placed in prone position. 4 cm of incision was made on the middle of skin between spinous processes in lesion clearance. After incising subcutaneous tissues and deep fascia, sacrospinal muscles were split along the margin of the affected side and vertebral plate to fully expose vertebral plate and zygapophyseal joint on surgical site. Gun-shaped rongeur was used to remove the partial vertebral plate. Then the laminotomy was performed to eliminate epidermal ligamentum flavum and expose theca vertebralis and nerve roots. After herniated intervertebral disc tissues were exposed, herniated nucleus pulposus and residual diseased tissues in intervertebral disc were removed. Spinal canal and nerve roots were re-examined, and nerve roots were decompressed. After rinsing the wound and hemostasis, one drainage tube was indwelled, after which the wound was sutured.

PTED group: Patients received PTED and the operation was performed according to the reference of Wu et al.[9].

Observational indexes

The surgical duration, incision length, postoperative bed-rest and hospital stay were compared between two groups, and the visual analogue scale (VAS), Oswestry disability index (ODI), and therapeutic effects at the final follow-up time were recorded in 2 groups.

Evaluation criteria

VAS [10]was used to assess pain intensity before and after operation. 0: no pain; 1-3 points: mild pain; 4-6 points: moderate pain; and 7-10 points: severe pain. The higher the score was, the severer the pain was. ODI [11]questionnaire was used to investigate the effect of backache on activities of daily life (ADL) of patients. ODI questionnaire contained ten questions, with the highest score being 5 points. The higher the score was, the severer the functional disorders became. Therapeutic effects at the final follow-up time were assessed by Macnab evaluation standard recorded in Li et al.[12].

Statistical analysis

SPSS15.0 Software package was used for all data analysis. The ranked data were analyzed using rank-sum test. The measurement data with normal distribution were expressed as mean± standard deviation, and intra-group comparison was analyzed using one-way analysis of variance and comparison among groups was analyzed by independent-sample t test. A value of P< 0.05 was considered statistically different.

Results
Operative and follow-up outcomes of two groups

Patients in both groups completed surgery smoothly and none was transferred to other surgical methods. One patient in FTED group had transient hyperpathia of lower limbs and was remitted completely two weeks after treated with mecobalamine. While 3 patients in FD group had aggravated neurological symptoms of lower limbs, and got better after treated with neurotrophins, hormones and dehydration with mannitol postoperatively. There was no severe complication, such as positioning error, intervertebral infection, and imparement of large vessels and nerve roots in two groups. In addition, all patients were followed up, with an average time of 12 months (8-19 months), and none had recurrence during follow-up period.

The surgical duration in PTED group was longer than that in FD group (P> 0.05). And incision length, postoperative bed-rest and hospital stay in PTED were superior to those in FD group (P< 0.01) (Table 2).

Table 2 Comparison of Surgical Duration, Incision Length, Postoperative Bed-rest and Hospital Stay Between Groups( x̅± s
VAS score in two groups before and after operation

There was no statistical difference in VAS score between two groups before operation (P> 0.05). Compared with treatment before, VAS score significantly decreased in both groups after operation, and the difference was significant (P< 0.05). Although VAS score in PTED group was lower than that in FD group after operation, there was insignificant difference between two groups(P> 0.05) (Table 3).

Table 3 Comparison of VAS Score Between two Groups Before and After Operation( x̅± s) Points
ODI score in two groups before and after operation

There was no difference in ODI score between groups before operation (P> 0.05). Compared with treatment before, ODI score significantly decreased in both groups after operation, and the difference was significant (P< 0.05). Although ODI score in PTED group was lower than that in FD group after operation, the difference was insignificant (P> 0.05) (Table 4).

Table 4 Comparison of DOI Score Between two Groups Before and After Operation ( x̅± s) Points
Comparison of therapeutic effects at the final follow-up time

Therapeutic effects at the final follow-up time were assessed by modified Macnab evaluation standard. In PTED group, 26 cases were rated “ excellent, 19 rated “ good” , 3 rated “ fair” , and 2 rated “ poor” . In FD group, 24 cases were rated “ excellent” , 21 rated “ good” , 2 rated “ fair” , and 3 rated “ poor” . There was no statistical difference in “ excellent and good” rate between two groups (90.00% vs. 90.00%, Z=-1.113, P=0.266).

Discussion

Patients with LDH often suffer from pain caused by autoimmunity, mechanical compression, and bladder function, etc.. PTED, a new surgery for the treatment of LDH, can reduce anesthesia risk under local anesthesia [13]. Meanwhile, patients can not only eat normally before operation, but also turn over and eat food by themselves after operation. Due to small incision (about 0.5 cm), PTED can relieve patients’ pain and lower the incidence rate of postoperative infections to a large extent when compared with FD which may cause large incision and high operative risk under general anesthesia [14]. Additionally, due to the safety of anatomical location, and under direct vision through endoscope, the new technique rarely causes any injury to important organs and tissues [15].

In present study, the postoperative bed-rest of PTED group was about one day which meant that patients could leave bed and did activities almost within one day. A shorter hospital stay in PTED group showed that patients got better after operation. Moreover, a smaller incision in PTED group than FD group indicated that PTED had a slighter trauma, and maximally reduced patients’ pain, so that patients might have less pain after operation. Those results were almost consistent with Tenenbaum et al. [16]. VAS and ODI scores significantly decreased in both groups after operation, and the difference was significant (P< 0.05), but there was insignificant difference in those two indicators between two groups after operation (P> 0.05), which were consistent with the results of Choi et al. [17]. No statistical difference was found in “ excellent and good” rate between two groups, showing that PTED and FD were all effective in the treatment of LDH. However, PTED had smaller incision, shorter hospital stay and rapid recovery. Therefore, long-term therapeutic effects deserved to be further explored.

As for skills of PTED, several points should be taken into consideration: (1) Before operation, doctors need to encourage patients to eliminate the anxiety and worries so as to increase their compliance. (2) Closed long needle is used to improve the effect of local anesthesia for deep tissues. (3) Adem-positionvertebra lumbalis X-rays, dynamic radiographs, lumber MRI, and CT are carefully observed before operation to determine the puncture point, angle, and location. (4) The needle should be used towards the head and the outside for patients with posterior-lower herniation of nucleus pulposus and to the outside for those with obesity. (5) Nucleus pulposus should be fully stained, which is conductive to the confirmation of location of nucleus pulposus under endoscope, surgical operation and inspection of residual nucleus pulposus. (6) The needle should enter into herniated nucleus pulposus and intervertebral disc. (7) Surgical field is carefully identified during the operation to fully decompress and avoid postoperative recurrence.

Declaration

The authors of this manuscript declare that they have no conflicts of interest.

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