A Suture Technique for Ruptured Annulus Fibrosus Following Decompression Under Percutaneous Transforaminal Endoscopic Discectomy

Summary

This protocol describes an innovative suture technique for ruptured annular fibrosus during percutaneous transforaminal endoscopic discectomy.

Abstract

The suture technique for a ruptured annulus fibrosus (AF) under full-endoscopy remains challenging. Direct suturing of a ruptured annular tear after full decompression has been shown to decrease the recurrence rate of lumbar disc herniation during endoscopic surgery. Traditional suture operations under endoscopy involve only simple suturing of the ruptured AF. Due to the weak and poor quality of the AF tissue around the tear portal, using this area as needle insertion points during suturing may lead to insufficient tension and a low success rate of AF closure. Currently, there is no detailed technical illustration based on video for AF tear suturing under lumbar full-endoscopy. We innovatively propose a method of covering and suturing the AF tear by pulling up the posterior longitudinal ligament (PLL) under lumbar endoscopy and using three stitches (PLL-AF suture technique). The patient who received the novel suture technique achieved satisfactory results. Six months after the operation, lumbar MRI showed no evidence of recurrence in the outpatient clinic.

Introduction

Percutaneous transforaminal endoscopic discectomy (PETD), a minimally invasive procedure used to remove herniated discs in the lumbar spine, is performed with an endoscope - a thin tube with a camera and light at the tip that enables the surgeon to visualize internal tissues and surrounding structures on a monitor¹. With real-time image guidance on the monitor, surgeons can perform positioning, puncture, and placement of the cannula² through a small skin incision of approximately 1 cm. Step-by-step exposure under the endoscope follows, including the removal of surrounding soft tissue and foraminoplasty to enlarge the opening of the targeted lumbar foramen. Once a clear view and sufficient operating space are achieved, complete decompression of the lumbar nerve is performed by removing the compressive fragments³.

Preventing postoperative recurrence of disc herniation remains a long-term concern for spine surgeons. One strategy during surgery to minimize the risk of recurrence is to remove all suspected detached nucleus pulposus (NP), even if it has not yet herniated into the canal. This is because a ruptured annulus fibrosus (AF) cannot be fully repaired, and as a result, detached NP tissue susceptible to intradiscal pressure may potentially reherniate in the future⁴.

Despite promising advancements in tissue engineering for repairing and regenerating the nucleus pulposus (NP) and annulus fibrosus (AF), none of them have been clinically proven effective⁵. The direct closure of the AF tear after full decompression is an important technique for reducing the risk of recurrence in lumbar disc herniation (LDH). Currently, the most frequently used suture technique for AF repair under endoscopy involves performing a simple suture with one single stitch at the site of the tear⁶. Apart from concerns about whether a single stitch can generate enough tension, an insufficient suture area (both in terms of quality and quantity) on both sides of the annular tear is frequently encountered after endoscopic decompression.

Therefore, this study proposes a new technique for suturing the AF after decompression of PETD by pulling and suturing the nearby posterior longitudinal ligament (PLL) over the AF tear with three stitches (PLL-AF suture technique).

Protocol

The protocol adheres to the regulations stipulated by the ethical committee of Huazhong University of Science and Technology Union Shenzhen Hospital, which has granted approval for the protocol. The written informed consent from the patient was obtained. A 31-year-old female patient was enrolled, who had suffered from consistent left leg radiating pain with a visual analogue scale (VAS)⁷ equal to 8. Physical examination findings were as follows: (1) upper body side bending to the right; (2) restricted range of motion in leaning forward and back; (3) positive left straight leg raising test and Braggard test; (4) left tibialis anterior strength grade 4; (5) numbness in the lateral area of the left lower leg and dorsum of the left foot. A positive lumbar 4-5 disc herniation (left paramedian type) was confirmed with MRI. She had experienced ineffective outpatient conservative therapy, including rest, non-steroidal anti-inflammatory drugs (celecoxib 200 mg/day for 6 weeks), and acupuncture for two months. The surgical tools and equipment used in the study are listed in the Table of Materials.

1. Decompression under endoscope

1. Position and anesthesia
   1. Perform endoscopic lumbar discectomy through a transforaminal approach⁸. Place the patient in a prone position and mark the skin puncture point under fluoroscopic guidance. Inject 0.5% lidocaine (10 mL) into the puncture point after local disinfection and draping.
2. Puncture and cannula placement
   1. Puncture using an 18 G needle at the marked puncture point and adjust the position under fluoroscopy. Step by step, insert the dilatation cannula (3.7 mm in diameter) and confirm reaching an ideal position under fluoroscopy.
3. Endoscopic lumbar decompression
   1. Insert trephine saws of different sizes (5 mm, 8 mm, and 10 mm in diameter) and rotate to remove bone on the cranial, dorsal, and caudal aspects of the superior articular process of L5 to perform foraminoplasty⁹.
   2. Expose step by step and remove soft tissues. Visualize around the suspected area of the herniated disc (a hilly-like shape, usually significantly different from the surrounding flat area). Determine the targeted herniated disc and the compressed nerve root¹⁰.
   3. Identify and remove the herniated and loose disc (including AF, NP, and cartilage endplate). Examine the decompressed nerve root and confirm no residual discs are present.
      NOTE: To identify the targeted herniation, our experience is to assess the color, texture, and shape of the disc material. Ruptured or herniated discs may appear discolored, fragmented, or displaced compared to the surrounding normal tissue. To examine the condition of the decompressed nerve root, allow the patient to cough and observe the "pulsation" state of the decompressed nerve root¹¹.

2. PLL-AF suture technique

1. Penetration of the lateral AF tear
   1. Use a disposable annular stapler for endoscopic suture¹². Identify the AF tear and penetrate the first stitch (silk made, 0.4 mm in diameter) using a curve-shaped needle in the annular stapler into the intact lateral AF tissue (Figure 1A). Check and confirm that the stitch is anchored securely (Figure 1B).
2. PLL suturing
   1. Penetrate the second stitch (silk made, 0.4 mm in diameter) into the PLL and confirm it penetrates also through the below medial intact AF. Check and confirm that the stitch is anchored securely. Then, tighten the first and the second stitches with a square knot (Figure 1C).
      NOTE: Identifying the PLL after decompression can be challenging at times. Careful operation and determination of the medial and dorsal regions of the spinal canal are suggested.
3. The third strengthen stitch
   1. Cut the first stitch (Figure 1D) and penetrate the third stitch (silk made, 0.4 mm in diameter) at the lateral area of the intact AF and at the cranial position of the second stitch (Figure 1E).
   2. Check and confirm that the stitch is anchored securely. Cut both two stitches after making a square knot (Figure 1F). Check the nerve root again and make sure no compression exists.

3. Postoperative management

1. Administer 50 mg of flurbiprofen axetil intravenously for postoperative pain.
2. After surgery, permit the patient to leave the bed one day postoperatively, provided no special conditions or complications arise, and provide a lumbar brace¹³ (semi-rigid type with metal or plastic struts for support).

Representative Results

After successful and sufficient decompression, the herniated disc at L4/5 (Figure 2A,A') was resected. Local AF tear (both medial and lateral tear edges) and PLL were identified under the endoscope. The first stitch ensured that the lateral tear edge was contained and sutured. The PLL and the medial AF tear edge were penetrated and stitched along with the first stitch. A third fastened stitch was tied with the second stitch at the cranial side of the first stitch. The key point of this technique is to penetrate the PLL and the medial intact AF and pull to cover and stitch the lateral AF tear.

The demographic information, clinical data, surgical outcomes, and follow-up data of the patient are shown in Table 1. The total operation time was 83 min. The patient was allowed to leave the bed one day after surgery with a lumbar brace. The postoperative VAS⁷ for leg pain decreased to 1 point. Postoperative MRI showed the successful decompression of the left L4/5 nerve root (Figure 2B,B'). The numb sensation in the lower leg and foot significantly decreased, and the left tibialis anterior strength improved to grade 4+ on the day of discharge. At the six-month follow-up, lumbar MRI was performed, and no evidence of recurrence was observed (Figure 2C,C'). The patient reported no radiating pain or numbness in his left lower limb.

Figure 1: The schematic diagram of the novel 3-stitch annulus fibrosus (AF) suture technique under endoscope. (A) Local structure of the target level after decompression (PLL indicates the posterior longitudinal ligament). (B) Penetration the first stitch at the lateral section of the AF. (C) Penetration of the second stitch at the PLL and tightening with the first stitch to tie a square knot. (D) Cutting the first stitch yet retaining the second stitch. (E) Penetrating the third stitch at the lateral section of the AF and at the cranial position of the second stitch. (F) Cutting the two stitches after knotting. Please click here to view a larger version of this figure.

Figure 2: Preoperative and follow-up lumbar MRIs of the patient under PETD using PLL-AF suture technique. (A) and (A') indicates the preoperative sagittal and axial MRIs, showing L4/5 herniation with left nerve root compression. (B) and (B') indicates the postoperative MRIs, the nerve root was decompressed. (C) and (C') indicates the lumbar MRIs at six-month follow-up. Please click here to view a larger version of this figure.

Parameters	Values
Age (years)	31
Gender	Female
BMI#	25.3
Herniation location	L4/5
Herniation type	Left paramedian type
Operation time (minutes)	83
Preoperative VAS*	8
Postoperative VAS	1
VAS at 6m follow-up	0
#BMI: body mass index; *VAS: visual analogue scale.

Table 1: Summary of the demographic information, clinical data, surgical outcomes, and follow-up data of the enrolled patient.

Discussion

Achieving excellent AF suturing under the endoscope has significant benefits. It is expected to reduce the nerve mechanical stimulation caused by AF rupture or bulge, thereby decreasing postoperative residual discogenic low back pain and/or sciatica pain^4,12. Closing the annular tear portal can reduce nerve root irritation caused by the release of inflammatory mediators from the intervertebral disc⁵. Additionally, patients can feel more confident mobilizing early after surgery. This confidence contributes to an accelerated recovery process and better outcomes in terms of regaining strength and function¹⁴.

This study introduces a novel AF suturing technique that uses the PLL as the suturing material for the first time, providing a new approach to address the inadequate tension resulting from the traditional single-stitch suturing method and the lack of healthy or firm AF tissue available around the tear after decompression. Moreover, the PLL was tightly sewn above the AF tear, allowing for an increased lumbar canal volume at the compressed segment. During the second stitch placement under endoscopic guidance, it was crucial to ensure the simultaneous penetration of both the PLL and the healthy AF in the medial portion of the tear, while avoiding contact with the nerve root.

In the literature, few studies have reported the AF suturing technique of PETD^4,6,15. Most studies have focused on AF suture after lumbar micro endoscopic discectomy (MED) or open discectomy. According to a recent meta-analysis that examined 7 randomized controlled studies and 8 observational studies, it was found that discectomy combined with AF suture can effectively lower the rates of postoperative recurrence and reoperation in patients suffering from LDH¹⁶. Li et al.¹² found that the combination of AF suture and autologous conditioned plasma intradiscal injection has been studied and shown to effectively decrease the recurrence rate of LDH by 4% when compared to cases where no suture was applied. Another study comparing the clinical outcomes of PETD with MED for AF suture after decompression reported that the MED technique exhibited better preservation of disc height and displayed advantages in terms of a lower recurrence rate, although no statistical difference was observed between the two techniques¹⁷.

There were two limitations to this technique. One prerequisite for realizing this technique is that the surgeon must possess rich experience in endoscopic procedures. As a result, there is a certain learning curve associated with the development of this technique. Second, this research was a technical report. The long-term effectiveness of this suturing technique should be examined in a larger sample population. Third, this technique was not applicable for every case with LDH. For instance, if the AF tear became too narrow after decompression, suturing may not be required.

Materials

Name	Company	Catalog Number	Comments
0.5% lidocaine	Beijing Tide Pharmaceutical Co., Ltd	H37022768	For postoperative pain
Dilatation cannula	Beijing Tianqi Medical technology Co., Ltd., Beijing	ZJ289019	Cannulation
Disposable annular stapler	Medical Science & Technology Co., Ltd., Beijing	SMILE-L, 2020	Suture
Disposable stitches	Medical Science & Technology Co., Ltd., Beijing	SMILE-L, 2020-022	Stitch
Flurbiprofen axetil	Shandong Hualu Pharmaceutical Co., Ltd.	H20041508	For postoperative pain
Puncture needle	Beijing Tianqi Medical technology Co., Ltd., Beijing	ZJ289033	Puncture
Trephine saws	Beijing Tianqi Medical technology Co., Ltd., Beijing	ZJ289036	Foraminoplasty