Keywords lumbosacral disk degeneration disorders - endoscopic biportal surgery - minimally
invasive spine surgery - lumbar interbody fusion - degenerative spondylosis
Introduction
Degenerative lumbosacral spondylosis (DLS), with concomitant neurologic deficit and
functional disabilities, is typically managed via surgery.[1 ] Despite the clinical efficacy of this approach, intraoperative and postoperative
complications have led to the demand for a minimally invasive approach.[2 ]
Biportal endoscopic spine surgery (BESS) is being increasingly applied to diskectomy
and decompression surgery.[3 ] This method adheres to the minimally invasive principle; at the same time, it is
designed to realize the essence of surgical intervention by securing an increased
degree of freedom for the surgeon's hand and a wide view suitable for complex bony
vertebrae. Moreover, reports on its efficacy and safety are increasing.[4 ] The surgeon can approach the anterior and posterior structures of the spine through
a posterior approach with the preservation of support structures. Bilateral multilevel
application is also possible.[5 ]
It may seem unreasonable to apply a minimally invasive method to the extensive surgery
of multilevel degenerative spondylolisthesis. However, the advantages of BESS may
be valid for sufficient decompression and careful exploration. Reports on the feasibility
of BESS interbody fusion in cases of lytic spondylolisthesis and single-level degenerative
spondylolisthesis have been published.[6 ]
[7 ]
[8 ]
Thus, here, we aim to describe a surgical technique of decompression and interbody
fusion using the BESS and present clinical and radiologic results in patients with
severe multilevel DLS.
Methods
This retrospective case study was conducted in compliance with the Declaration of
Helsinki and approved by the institutional review board. Informed consent was obtained
from each patient.
Both patients had two or more adjacent lesions. Data were gathered retrospectively
and analyzed after receiving approval from the institutional review board. The data
were as follows: inpatient and outpatient medical charts, nursing records, surgical
records, images, and logon records from hospital information systems.
Surgical Techniques
The surgery was performed under general anesthesia. Intraoperatively, each patient's
blood pressure, heart rate, electrocardiogram, oxygen saturation, and respiratory
rate were monitored. The patients were placed in the prone position. Their backs were
gently flexed by placing the Wilson frame under the abdomen. The frame was fixed using
a soft strap on the trunk and thighs for stabilization. The lumbosacral region was
exposed, while the rest of the body was covered with sterile drapes. The target site
was identified under fluoroscopy, and incisions were made bilaterally based on the
intervertebral disk levels for cage insertion.
Step 1. Incision. Two portals were constructed as follows: the entry points were marked 1 cm above
and 2 cm below the target intervertebral level (lower margin of the upper lamina)
and 0.5 cm laterally from the spinous midline. The marked skin can be opened by 1 cm
using the transverse incision method, providing low resistance to major movements
of the inserted devices, thus reducing damage to the longitudinal muscle fibers. The
cranial portal was used for continuous irrigation and endoscopy, and the caudal portal
was used for the operating devices. Three sets of two portals have a total of eight
incision lines bilaterally and sharing a caudal portal on the upper level and a cranial
portal on the lower level ([Fig. 1 ]).
Step 2. Approach. After muscle exfoliation using a dissector, a 30-degree endoscope with a 4-mm diameter
was inserted into the target lamina. A continuous irrigation system was connected
and controlled to set a pressure of 50 mm Hg. After ensuring a clear endoscopic view,
an indicator was inserted into the caudal portal to identify the tip through the endoscopic
view. Target points and instrument placement were confirmed through fluoroscopy.
Step 3. Laminectomy and facetectomy. The interlaminar ligament was resected 1 to 1.5 cm transversely. Partial laminectomy
was performed using an elliptical arthroscopic burr. After inspecting the dura mater,
the thickened ligamentum flavum (LF) was removed using a Kerrison punch. The neural
structures of the spinal canal and foramen were inspected. The endoscope was inserted
deeply to check the subarticular annulus fibrosus, and the contralateral LF and epidural
space were then inspected by rotating the 30-degree endoscope ([Fig. 2 ]). The total inferior articular process and partial superior articular process were
subsequently removed using an osteotome and a chisel, thus securing the cage insertion
space and root decompression. Bone fragments were picked up.
Step 4. Disk space preparation and cage insertion. Approaching the subarticular annulus fibrosus, disk materials were removed through
an incised hole of the herniated annulus. The cartilage of endplate was scraped to
induce bone union using a curette and a reamer. The reserved intervertebral space
enabled the direct entry of the endoscope. The cage size was defined by the last reamer
size. A mixture of harvestet local bony fragments with demineralized bone matrix (DBM)
was packed in the cage. In this process, the neuromuscular structures were protected
through a retractor.
Step 5. Contralateral decompression. Once it was confirmed, through endoscopy and radiography, that the cage placement
was stable, the contralateral LF was removed and decompression was added ([Video 1 ]). When the 30-degree endoscope was rotated 150 degrees axially at the level of posterior
epidural space, the contralateral LF and dura were identified. The contralateral recess
decompression byLF removal using the punch enabled endoscopic identification of the
contralateral traversing spinal root.
Step 6. Repetition of steps 4 and 5 according to the target levels. Since the intervertebral height was restored through these operating steps, the decompression
was performed form the caudal to the cranial level to prevent a traction injury of
nerve roots.
Step 7. Percutaneous pedicle screw fixation. Under radiography, pedicle screws were inserted. Reduction was tried, and the presence
of a listhesis was considered. The pedicle screws and the rods were locked.
Step 8. Inspection before closing. Bleeding and the integrity of spinal and neurovascular elements were closely monitored
through endoscopic exploration. By seeing the dural pulsation caused by normal breathing,
the degree of decompression was evaluated endoscopically. Once all the instruments
were removed, a subfascial hemovac was inserted and the skin was sutured ([Fig. 3 ]).
Step 9. Postoperative management. Walking with a rigid brace was allowed on the day after surgery once stable vital
signs were confirmed. The patients were discharged 3 to 5 days after surgery.
Fig. 1 Overview of biportal endoscopic spine surgery for multilevel degenerative lumbosacral
spondylosis (target levels: L2/L3, L3/L4, and L4/L5). Three sets of two portals have
a total of eight incision lines bilaterally, sharing an upper caudal portal and a
lower cranial portal.
Fig. 2 Endoscopic views on the L3/L4 epidural space. Left: The dura, nerve root sleeve,
and nerve root (solid
arrowhead ) above the annulus (open arrowhead ). The dotted line is the resected lamina. Right: Contralateral epidural space. The arrow points at the foramen.
Video 1 Endoscopic view during total diskectomy and cage insertion in biportal endoscopic
spinal surgery (BESS) for L4/L5 interbody fusion.
Fig. 3 The sutured skin of the portals and inserted subfascial Hemovac drain immediately
after surgery. Eight incisions were placed bilaterally and the target levels were
L2/L3, L3/L4, and L4/L5.
Case 1
A 75-year-old woman with no history of trauma was admitted to the hospital with chronic
hip pain, continuous radicular pain, and severe claudication that had lasted 5 years.
She reported that even if she walked only 10 steps, she felt calf pain and weakness,
so she had to sit down and rest. She had been taking limaprost 5 µg three times a
day, 37.5 mg of tramadol, and 325 mg of acetaminophen on an irregular basis for 10
months. In the last month, the buprenorphine patch (10 µg/h, total 10 mg) has been
used every week, but there has been no symptomatic improvement. A plain lumbosacral
radiograph showed compression fractures of the third, fourth, and fifth lumbar vertebrae
with severe degenerative changes in the endplates and facet joints. On magnetic resonance
imaging (MRI), L3/L4, L4/L5, and L5/S1 disk herniations and severe stenosis of the
foramen and spinal canal were observed. Difficulty in ambulating for more than 30 m
was noted, and the extensor and flexor muscles of both ankles showed grade 4 muscle
weakness. Previous surgical history included a partial gastrectomy for gastric cancer
2 years prior. She was taking an antihypertensive medication.
She underwent biportal endoscopic decompression with a three-level interbody fusion
from L3 to S1 through the unilateral biportal approach at each level. The duration
of operation was 170 minutes, and blood loss was 500 mL. Postoperative MRI and X-ray
images demonstrated an improvement in the lumbar lordosis, significant decompression
of the neural structures, and well-placed implants ([Fig. 4 ]).
Fig. 4 Pre- and postoperative images of the case 1. (A,B ) Preoperative radiographs. (C,D ) Preoperative spine magnetic resonance imaging (MRI). (E,F ) Radiographs 3 months after the surgery.
Ambulation with minimal assistance was initiated on the third postoperative day. There
was gradual relief of pain and claudication; 8.9 to 3.2 on the visual analogue scale
(VAS) of back pain, 7.4 to 1.5 on the VAS of leg pain, and 66.7 to 19.8% on the Oswestry
disability index (ODI) score 4 weeks postsurgery. Even if she walked more than 30 m
indoor, no pain or weakness occurred. There was no evidence of pseudoarthrosis or
neurologic deficits at the 1-year follow-up. At this time, she reported that she could
walk about a distance of ∼150 m without a rest. Acetaminophen was taken due to intermittent
low back pain, but it did not exceed once a week.
Case 2
A 73-year-old woman presented with chronic low back pain and radicular pain and severe
claudication in both legs that had lasted 8 years. The symptoms were more dominant
on the right and were recently observed to worsen upon coughing. She had difficulty
walking independently. She was able to move about 5 m under a minimal assistance,
but had to rest due to right severe leg pain and bilateral legs weakness. She was
taking celecoxib 100 mg and gingko leaf extract 40 mg twice a day for 1 year, and
was also taking oxycodone 5 mg irregularly to recent exacerbated pain. A plain lumbosacral
radiograph showed degenerative malalignment of the second to fifth lumbar vertebrae
with severe degenerative changes in the endplate and facet joints. On MRI, lumbar
disk herniations and severe stenosis of the foramen and spinal canal were observed.
The extensor muscles of both ankles showed grade 3 muscle weakness and the flexor
muscles of both ankles and knees showed grade 4 muscle weakness. Electrophysiologic
studies showed chronic bilateral L5 and S1 radiculopathies. She was taking antihypertensive
and antiglycemic medications.
The patient underwent biportal endoscopic decompression with three-level interbody
fusion from L2 to L5. The duration of operation was 160 minutes, and blood loss was
650 mL. Her scoliosis improved partially after surgery. Sufficient decompression was
achieved through increase of the intervertebral and foraminal space ([Fig. 5 ]).
Fig. 5 Pre- and postoperative images of the case 2. (A,B ) Preoperative radiographs. (C,D ) Preoperative spine magnetic resonance imaging (MRI). (E,F ) Radiographs 1 month after the surgery.
She was able to walk with a rolling walker 2 days after surgery. After 4 weeks, her
symptoms gradually improved: 8.1 to 2.8 on the VAS of back pain, 7.2 to 1.9 on the
VAS of leg pain, and 58.2 to 11.8% on the ODI. She showed a dramatic improvement in
claudication, allowing her to walk three times 20 m without a rest. No pseudoarthrosis
or neurologic deficits were observed, and the strength of the extensor muscles of
both ankles improved to grade 4 on follow-up 18 months after surgery. At this time,
she reported that she had no difficulty walking and said she could climb a low-height
hill. She mentioned that she often had low back pain with minimal to moderate intensity
when walking continuously for more than 30 minutes outdoor, but the pain resolved
after resting. She did not report taking any analgesics due to pain.
Discussion
Innovations in endoscopic instruments and surgical techniques have shifted the treatment
paradigm for degenerative lumbar spine disease from open surgery to minimally invasive
surgery.[9 ]
[10 ] Various methods, depending on the approach, direction, and the structure to be removed,
are available. However, the principles of endoscopic decompression and fusion maintain
the concepts of open decompression with interbody fusion. Unnecessary damage should
be limited based on the principle of minimal invasiveness, but the minimal intervention
should be sufficient for resection, decompression, reduction and fixation. Resection
of the facet joint and annulus fibrosus is unavoidable in most minimally invasive
techniques.[11 ]
[12 ]
[13 ]
Aging initiates disk degeneration through dehydration and fragmentation of the nucleus
pulposus.[14 ]
[15 ] Degeneration affects the distribution and balance of the load on the annulus fibrosus.
The accumulated load causes structural problems such as a break in annular continuity,
instability of intervertebral joints, thickening of ligaments, and a decrease in the
height of the intervertebral foramen; thus, a vicious cycle develops.
Surgical decompression should be considered for significant neurologic deficits. Options
include decompression with extensive osteotomy, and fusion as an additional treatment.
Studies on surgical outcomes were subjected to Cochrane review, which revealed a lack
of high-quality evidence.[16 ] Case reports showed favorable surgical outcomes with low complication rates.
Reports on BESS are increasing as this method allows sufficient decompression and
wide exploration as do the conventional method, but is minimally invasive. If performed
on severe stenosis, favorable outcomes can be expected, BESS is applicable to multilevel
disease.[5 ] Endoscopic decompression through the posterior approach can minimize the incision
site, and the direct endoscopic approach to the annulus fibrosus enables real-time
confirmation of the insertion pathway of the interbody cage. In addition, it is possible
to disperse the load applied to the implanted rods and screws by preserving the supportive
bony structures as much as possible.
Here, we used BESS for the surgical treatment of multilevel degenerative spondylosis
with concomitant radiculopathies and claudication. The two patients were at high risk
for conventional surgery because of old age, and multilevel disease. Blood loss is
higher in conventional surgery, which is associated with more complications especially
in older patients. Selective decompression of severe intervertebral foramen stenosis
was indicated to prevent the additional neurologic complications that can occur while
re-establish lordosis with fusion. There were additional advantages of BESS such as
the possibility to remove herniated disk material, to insert a cage and to perform
annuloplasty; moreover, multilevel treatment is possible.[3 ]
[5 ] Clinical outcomes showed remarkable pain reduction, fewer complications, and early
ambulation. Daily activities improved gradually, without pseudoarthrosis or additional
neurologic deficits during follow-up. There was high patient satisfaction with the
surgery. Attention to the longer operation time is necessary. Constant irrigation
with pressure to secure the field of endoscopic view during manipulation can cause
neurologic damage. Evidence of increased epidural pressure during surgery has been
reported.[17 ] The intraoperative irrigation pressure should be kept below 50 mm Hg; further, if
possible, neurologic monitoring is recommended.
Conclusion
More reports on the type, severity, and incidence of complications as well as the
effectiveness of surgery are necessary. BESS can be applied to multilevel degenerative
spondylosis. BESS provides freedom for the surgeon's hand and a sufficient operative
view.
