Advanced technique of biportal endoscopic transforaminal lumbar interbody fusion for revision surgery: a technical note
Article information
Abstract
The application area of biportal endoscopic spine surgery (BESS) is gradually expanding. Compared with conventional fusion surgery, transforaminal interbody fusion (TLIF) using BESS (BESS-TLIF) has the advantages of less bleeding, minimal postoperative pain, and faster recovery. This technical note highlights its application in managing complex conditions such as scar tissue adhesion, altered anatomy, and implant removal, common in reoperations. The method focuses on precise dissection, endoscopic visualization, and careful tissue handling to ensure effective decompression and stabilization. Three representative cases, including reoperations for recurrent disc herniation, adjacent segment disease (ASD) following prior fusion, and ASD with nonunion of the prior fusion site requiring fusion extension, were described. All three cases exhibited clinical improvement following surgery. BESS is an effective and safe method for spinal revision surgery not only in simple decompression surgery but also in cases that required fusion surgery. As BESS is advancing, its role in complex spinal surgeries is expected to expand, potentially setting new standards in minimally invasive spine surgery.
Introduction
The development of biportal endoscopic spine surgery (BESS) has led to the gradual expansion of its application area in spine surgery. BESS is performed not only in simple discectomy but also in the decompression of spinal stenosis and transforaminal lumbar interbody fusion (TLIF) [1,2]. Compared with minimally invasive TLIF using a tubular retractor, BESS-TLIF demonstrates similar or superior results in terms of initial postoperative pain, blood loss, rehabilitation, and hospitalization period [3]. In addition, BESS appears to be useful in spinal reoperations. Kim et al. [4] reported the usefulness of the spine reoperation technique using biportal endoscopy.
TLIF can be performed as a follow-up procedure to address instability, degeneration, and back pain that occurred following the initial spine surgery for herniated intervertebral disc or stenosis. Compared with individuals who had not undergone surgery, tissue adhesions and altered anatomical structure may cause intraoperative difficulties. In addition, certain cases require fusion surgery for adjacent segment disease (ASD) occurring following the previous lower-level fusion surgery. In these cases, TLIF can also be performed using BESS. This technical note describes the BESS-TLIF technique as a reoperative procedure following previous surgery, focusing on soft tissue management and implant removal.
Technical Notes
BESS-TLIF in patients who previously underwent discectomy or decompression on the same side
At the previous partial laminectomy site, scar tissue is formed and adheres to the dura and bone. If surgery is performed without appropriate dissection of this area, iatrogenic dural tears or nerve injury may occur, requiring appropriate soft tissue handling.
Portal making
The level of each pedicle is checked using a C-arm image intensifier, and a vertical incision of approximately 1.5 cm is made just lateral to the pedicle (Fig. 1). In this technique, total facetectomy, decompression, and cage insertion are performed through an incision into which a pedicle screw is inserted. To allow for ideal pedicle screw insertion, each pedicle must be tilted and marked in a true view on the C-arm image intensifier.
The incision is made just lateral to the pedicle lateral margin or 1 cm lateral to the pedicle lateral margin considering convergence when inserting the pedicle screw. Before inserting the endoscope, a blunt instrument must be inserted through the incision to separate soft tissue and bone. At this time, with C-arm image intensifier, the previous laminectomy site (dotted line) must be identified, palpated, and carefully separated.
Soft tissue preparation with adhesiolysis
If partial laminectomy was performed previously, damage to the nerve tissue must be avoided because severe adherence of the scar tissue, bone, and dura exists. Initially, a blunt instrument is used to peel the soft tissue over the facet joint and lamina. Adherent scar tissue does not peel off easily. However, to prevent damaging the nerve tissue, the work must be done above the bone under the guidance of a C-arm image intensifier (Fig. 2A, B). Subsequently, a blunt instrument is used to palpate and confirm the safe area made of bone. Then, the scar tissue is cut using a surgical blade above the bone in the safe area (Figs. 2C, D, and 3A). Furthermore, the superficial scar tissue adhering to the dura is detached from bone, and the margin of the remaining bone is checked. The scar tissue is carefully peeled off from the bone margin to access the epidural space; however, if this is challenging, a little more bone is removed using a burr or Kerrison punch to secure a space (Fig. 3B). When the space leading to the epidural space is confirmed, adhesiolysis is performed to separate the scar tissue and bone carefully (Figs. 2E, 3C). Then, the scar tissue is removed up to the area where facetectomy will be performed to prevent the dura from being torn apart by the scar tissue when removing the inferior articular process (IAP) (Fig. 2F).
(A) It is difficult to access the epidural space at the previous surgery site because the scar tissue is heavily adhered to the dura and bone. (B) Safe area must be secured by checking the remaining bone area at the previous partial laminectomy site using a blunt instrument. (dotted line) (C, D) Use a blade to cut the scar tissue above the safe area made of bone, and when the bone below is exposed, the scar tissue is carefully removed. (E) Afterwards, the margin of the bone is checked and space is secured through additional bone resection to access the epidural space. (F) For facetectomy, separate the scar tissue and bone to the area where the bone needs to be removed and perform bone resection using an osteotome.
(A) Identification of the bone margin using a blunt instrument, followed by excision of the previous scar tissue with a surgical blade in a safe zone. (B) Additional bone resection using a high-speed burr to create sufficient working space, addressing adhesion between the scar tissue and bone. (C) Careful adhesiolysis of the epidural space using a blunt-tipped instrument through the secured space.
Facetectomy
The IAP of the upper vertebra is excised using an osteotome to the area where scar tissue dissection was performed, starting from just above the tip of the superior articular process (SAP) of the lower vertebra (Fig. 2F). When the medial margin of SAP is exposed, the dura lateral margin and bone are carefully separated using a blunt-tipped probe. After palpating the lower pedicle using a probe bent at 90°, facetectomy is performed by removing the SAP using an osteotome in the cranial area of the upper margin of the pedicle.
Disc preparation, cage insertion, and percutaneous instrumentation
If Kamabin’s triangle is found after facetectomy, a retractor is used to protect the traversing root without damaging the exiting root, and an annulotomy is performed using a blade. The retractor plays a role in securing visibility and protecting the root during disc preparation. After the disc has been sufficiently removed, an endoscope can be used to check whether the bony endplate has been sufficiently exposed. After disc space preparation, the cage is inserted by either inserting two cages or inserting one large cage. Then, the surgery is completed by inserting the pedicle screw and connecting the rod using the percutaneous technique.
TLIF at the adjacent level performed in ASD that occurred following previous fusion
Making incisions
If computed tomography (CT) confirms union of the lower segment, the existing screw can be removed. Initially, the C-arm image intensifier is used to check the location of the existing screw, and a 1.5-cm skin incision is made vertically. After checking the pedicle of the upper segment where the new pedicle screw is to be inserted, a 1.5-cm vertical incision is made on the lateral margin or 1 cm lateral to the lateral margin of the pedicle (Fig. 4).
The location of the incision indicated on the anterior-posterior plain radiograph (yellow line). Using the C-arm image intensifier, each pedicle and the inserted screw must be adjusted to the true view and then the incision should be determined.
Screw removal with endoscopy
If an endoscope is not utilized in implant removal, the process may be difficult owing to scar tissue formation and a narrow field of view. However, it can be removed relatively easily using an endoscope. The pedicle screw is checked under C-arm guidance, and a vertical incision of approximately 1.5 cm is made on the lateral margin of the screw head. Subsequently, a blunt instrument is used to push out the soft tissue, which is checked using an endoscope. At this time, a shaver is inserted through the same incision to clean up the soft tissue. Then, the scar tissue can be removed under direct observation using a blade or hook-type electrocautery, allowing for screw removal (Fig. 5A). Because the screw hole is directly visible, a bone chip and a new screw can be inserted easily (Fig. 5B). If screw reinsertion is unnecessary, a material such as bone wax is used to plug the screw hole.
(A) Schematic diagram of screw removal using biportal endoscopic spine surgery. (B) Appearance of screw confirmed on endoscope. (C) Screw hole confirmed after removing the screw. A new pedicle screw can be inserted through this hole.
BESS-TLIF
BESS-TLIF is performed on the adjacent segment. Given that no scar tissue exists in this area, it is performed in the same manner as other BESS-TLIF. First, the facet joint and resection part of the IAP and lamina are checked using the osteotome based on the tip of the SAP. Then, the SAP is removed, allowing the assessment of the disc space. After disc preparation, the cage is inserted.
Instrumentation
For the level where the screw was previously removed, the existing screw hole is checked using an endoscope, a bone chip is placed into the hole, and a screw that is one size larger is then inserted (Fig. 4C). Subsequently, a screw is inserted at the adjacent level using a percutaneous technique, and the rod is connected.
Case presentation
All patients provided written informed consent for the publication of clinical details and images.
BESS-TLIF in patients who previously underwent discectomy or decompression on the same side
A 42-year-old female patient, who had undergone three surgeries for L4–5 herniated intervertebral disc, underwent surgery at another hospital for the fourth recurrence 6 months before the outpatient visit. The patient complained of pain in the right lower extremity and back that occurred 2 weeks ago. The herniated intervertebral disc at the L4–5 level and the left laminectomy state were confirmed on magnetic resonance imaging (MRI) (Fig. 6A–C). For this, BESS-TLIF was performed (Fig. 6D, E), and the pain on the lower extremity and back improved.
(A) Plain lateral radiograph of the patient before surgery. T2-weighted sagittal (B) and axial (C) magnetic resonance imaging (MRI) shows a herniated intervertebral disc at the L4–5 level. (D) Plain lateral radiograph and (E) T2–weighted sagittal MRI taken after biportal endoscopic spine surgery–transforaminal interbody fusion.
BESS-TLIF performed in ASD that occurred following lower segment fusion
An 83-year-old male patient underwent L4–5 interbody fusion at a different hospital 2 decades ago and presented with pain radiating to the lower extremity and back pain that began 3 months before visiting Daechan Hospital. Lateral plain radiography confirmed L4–5 fusion and instrumentation, along with retrolisthesis of the L3–4 level (Fig. 7A). MRI confirmed retrolisthesis accompanied by central and both foraminal stenoses at the L3–4 level (Fig. 7B). Preoperative CT revealed bone union at the previous interbody fusion site (Fig. 7). Accordingly, the existing screw was removed, and BESS-TLIF was performed at the L3–4 level (Fig. 7D, E), resulting in relief from both axial pain and radiating pain.
(A) The patient’s preoperative plain lateral radiograph, L4–5 interbody fusion status, and L3–4 retrolisthesis are confirmed. (B) Central stenosis at L3–4 is confirmed on preoperative T2-weighted sagittal magnetic resonance imaging (MRI). (C) On preoperative computed tomography, union was confirmed at the previous fusion site between L4–5 level. (D) Plain lateral radiograph and (E) T2-weighted sagittal MRI image taken after L3–4 biportal endoscopic spine surgery–transforaminal interbody fusion.
Fusion extension with BESS-TLIF due to nonunion and ASD following previous surgery
The patient was a 73-year-old man who had undergone spine surgery 4 times before visiting Daechan Hospital. The last fusion surgery was performed 4 years ago. He complained of severe back pain and pain radiating to the lower extremities and had difficulty walking >100 m due to intermittent claudication. Preoperative X-ray imaging revealed interbody fusion of L3–4–5 and spondylolisthesis of L5–S1. At the L3–4 level, the pedicle screw was inserted only on one side (Fig. 8A). Preoperative MRI confirmed central and foraminal stenoses on L5–S1 (Fig. 8B). CT confirmed union at the L4–5 level but nonunion at the L2–3 level (Fig. 8C). Accordingly, BESS-TLIF was performed at the L5–S1 level, during which the existing implant was removed through BESS, and instrumentation was extended from L3 to S1 (Fig. 8D, E). Following surgery, the patient’s radiating pain and claudication, with back pain showing improvement 1 month further.
(A) A plain lateral radiograph taken before surgery shows L3–4–5 interbody fusion and spondylolisthesis of L5–S1. (B) Central stenosis at the L5–S1 level was confirmed on preoperative T2-weighted sagittal magnetic resonance imaging (MRI). (C) Preoperative computed tomography scan confirmed bone union at the L4–5 level, but nonunion was confirmed at L3–4 level. (D) Plain lateral radiograph and (E) T2-weighted sagittal MRI image taken after surgery.
Discussion
Performing surgery on patients who have undergone surgery often presents significant challenges for surgeons. These difficulties arise from the changes in the anatomical structure and the presence of dense scar tissue that strongly adheres to surrounding areas. Scar tissue, particularly when involving nerve structures, increases the risk of nerve damage intraoperatively. Consequently, the procedure often takes longer and may not be completed. To manage these complexities effectively, surgeons must have substantial experience and follow precise surgical principles while handling tissues with care. One of the most notable advantages of BESS is its superior visualization. Placing the endoscope in direct proximity to the target tissues offers a magnified and detailed view. The continuous flow of water not only removes debris and minor bleeding but also displaces the dura mater, creating an extra workspace without using suction devices that might obstruct the view. This setup allows surgeons to easily distinguish normal tissues, such as pinkish muscles and ligaments that exhibit a clear fiber orientation, from scar tissue, which appears pale and lacks any identifiable fiber structure. This improved visual clarity ensures that the surgery can be performed safely and accurately.
The scope of the application of BESS is gradually expanding. Studies have reported cases being treated with endoscopy in areas or conditions that were previously considered contraindications to endoscopic surgery. Kim et al. [5] reported treatments using BESS for various thoracic spine diseases. In addition, a study reported its application in the treatment of infectious diseases and tumors, which were previously considered contraindications of BESS [6–8]. Surgical applications using BESS also extend to revision surgeries. Kim et al. [4] reported on the use of BESS for treating recurrent disc herniation. In spine surgery, revision procedures can be particularly challenging because of adhesions caused by scar tissue and deviations from normal anatomical structures. However, the improved visualization provided by endoscopy allows for more precise and cautious handling of soft tissue, reducing the risk of nerve damage [4]. These advantages enable BESS to be effectively utilized in spine revision surgeries.
The advancement of spinal fusion techniques has greatly enhanced patient outcomes in the treatment of degenerative lumbar spine disorders. Since its introduction by Harms and Jeszenszky [9], TLIF has gained widespread popularity. Initially, early TLIF involved exposing all posterior elements and resecting the facet joint [10]. With the introduction of tubular retractors and percutaneous pedicle screw insertion, the procedure evolved into minimally invasive spine surgery (MIS)-TLIF, with reduced incidence of associated surgical morbidity [11]. As BESS became more widely accepted, its benefits were increasingly recognized, which led to the adoption of BESS for TLIF [12]. The emergence of BESS-TLIF marks a significant step forward in MIS, offering advantages over traditional MIS-TLIF, such as less postoperative pain, faster recovery, and shorter hospital stays [3].
In surgeries for adjacent segment pathology, no clear consensus has been established on whether to extend fusion using existing implants or remove them entirely, as this decision is often dependent on the surgeon’s preference. In revision surgeries, implant removal generally requires a longer incision, leading to significant blood loss and extended operative time [13,14]. However, as described in this study, BESS allows implant removal with minimal incision and reduced blood loss. A study reported that when only posterolateral fusion is performed without interbody fusion, maintaining the existing implant and extending the fusion can reduce the risk of mechanical complications compared with that when the implant is removed [15]. Therefore, implant removal should be performed when interbody fusion has been performed, and union was confirmed on CT. Otherwise, fusion extension, including the previous surgical level, is necessary. As described in case 3, in situations where stability must be maintained because of nonunion or instability at the previous surgical site, existing screws can be removed, and new pedicle screws can be inserted, with fusion-level extension achieved through the same incision.
This technical note focuses on the application of BESS-TLIF in revision spine surgery, and several limitations should be acknowledged. First, the techniques and outcomes described herein are based on limited case presentations, which may not be generalizable to all patients or surgical scenarios. Second, long-term follow-up data are nonexistent to evaluate the durability of BESS-TLIF in revision settings, particularly concerning adjacent segment degeneration and implant-related complications. Finally, surgical outcomes may be significantly dependent on the surgeon’s proficiency with BESS, which could limit its wider adoption. Further multicenter studies with larger sample sizes and extended follow-up periods are necessary to validate these findings.
In conclusion, BESS-TLIF represents a promising approach for revision spine surgery, offering the advantages of minimal soft tissue damage, reduced blood loss, and shorter hospital stays. This study demonstrates the utility of the technique in challenging cases, including those with significant scar tissue adhesions and ASD. As BESS is advancing, its role in complex spinal surgeries is expected to expand, potentially setting new standards in MIS. More studies are needed to establish long-term outcomes and refine surgical protocols, ensuring broader accessibility and safety for diverse patient populations.
Key Points
Biportal endoscopic spine surgery-transforaminal lumbar inter body fusion (BESS-TLIF) is an effective and minimally invasive approach for revision spine surgery, addressing challenges like scar tissue adhesion, altered anatomy, and implant removal.
The endoscopic technique offers superior visualization, enabling precise dissection and adhesiolysis, reducing the risk of dural tears and nerve injury in revision cases.
BESS-TLIF can be effectively applied to adjacent segment disease cases following prior fusion, allowing fusion extension with minimal soft tissue disruption and blood loss.
This study highlights the expanding role of BESS beyond simple decompression, demonstrating its feasibility in complex revision cases, potentially setting new standards in minimally invasive spine surgery.
Notes
Conflict of Interest
No potential conflict of interest relevant to this article was reported.
Author Contributions
Conceptualization: YIK, JYL, HCK, HGC. Data curation: YIK, JYL, HGC. Formal analysis: YIK, SHH. Funding acquisition: not applicable. Methodology: YIK, JYL, HGC, JWP. Project administration: YIK. Visualization: YIK. Writing-original draft: YIK. Writing–review & editing: YIK. Final approval of the manuscript: all authors.