Minimally invasive release fusion of mild to moderate lumbar isthmic spondylolisthesis slippage Tan Jun, Department of Spine Surgery, Shanghai Oriental Hospital
Section I. Overview of lumbar spondylolisthesis
I. Definition of lumbar spondylolisthesis
Herbiniaux, a Belgian obstetrician and gynecologist, was the first to notice the existence of this lesion in 1782, describing a case of L5 slipping forward on the sacrum. olisthesis” first introduced the name of lumbar slippage, defined as “the forward slippage of a vertebral body relative to its adjacent next vertebral body”. Taillard defined it in 1957 as “the forward slippage of a vertebral body together with its arch, transverse process and superior process due to continuous interarticular rupture or lengthening “.
Nowadays, we generally define lumbar spondylolisthesis as a partial or complete slippage of the surface of the upper vertebral body and the lower vertebral body due to abnormal bony connection between the vertebral bodies. The bony structures of the small posterior lumbar joints, the intact vertebral arch, the unextended pedicle, and the control of the vertebral body by the intervertebral disc all prevent the vertebral body from sliding forward. When the normal locking mechanism fails due to defective bony structures and disc degeneration, it can eventually lead to vertebral slippage. Lumbar spondylolisthesis is a pathological process in which a vertebral body slides forward relative to its subordinate vertebral body to produce clinical symptoms or signs.
Second, the classification of lumbar spondylolisthesis
The most widely used is the Wiltse-Newman-Macnab classification system proposed by Wiltse and Newman et al. in 1976 according to its etiology, including: dysplastic, isthmic, degenerative, traumatic and pathological.
Third, imaging of lumbar spondylolisthesis
Imaging examinations through X-ray plain film, multiplanar reconstruction with multi-detector alignment spiral CT, magnetic resonance imaging (MRI) and lumbar myelography can identify the type of slippage, evaluate the degree of slippage progression, interpret clinical symptoms and help physicians select appropriate treatment.
Before understanding the different types of slippage, the first step should be to define the indicators for measuring the degree of vertebral slippage. And the measurement of the degree of slippage is performed using standing lateral radiographs of the lumbar spine. Meyerding, an obstetrician, proposed the most common classification (Figure 13-1): I degree slippage = 25%, II degree slippage = 25% to 50%, III degree slippage = 50% to 75%, IV degree slippage = 75% to 100%, and V degree slippage > 100%, which refers to complete subluxation of lumbar 5 sacral 1, which becomes a spinal prolapse.
Figure 13-1 Meyerding classification method
Section 2: Lumbar isthmic spondylolisthesis slippage
I. Etiological classification of isthmic lumbar spondylolisthesis and its clinical manifestations
Most lumbar spondylolisthesis is asymptomatic and is often discovered unintentionally during physical examination. Patients presenting clinically with lower back pain are not necessarily the cause of the symptom, even if an isthmic dislocation or lumbar spondylolisthesis is found on radiographs. In Scott’s report, congenital lumbar spondylolisthesis accounted for approximately 40% of slipped patients, degenerative lumbar spondylolisthesis for 45%, and isthmus lesions, etc., for 15%. Congenital lumbar spondylolisthesis is clinically rare, and lumbar isthmus lesions and degenerative lumbar spondylolisthesis are common in adults. The symptoms and signs of patients are related to the type of lumbar spondylolisthesis, the stability of the spine, the degree of spondylolisthesis, and age and gender.
Isthmic cleft lumbar spondylolisthesis is most often seen in patients under the age of 50. Patients are mostly adolescents, with onset around the age of 6 and a high incidence between the ages of 11 and 15, and the incidence is four times higher in females than in males. Isthmic dislocation can occur at any level of the spine or can occur simultaneously in multiple segments, with simple isthmic dislocation being the most common, with slippage generally occurring between 20 % and 30 %.
The underlying lesion in isthmic fracture spondylolisthesis is a defect between the isthmus of the vertebral arch articulation, the etiology of which is still unclear. wiltse et al. speculated that fatigue fractures may have occurred in the isthmus, a lesion seen in congenitally weakly developed isthmus, with arch defects occurring most often between 5 and 7 years of age, further vertebral slippage occurring between 10 and 15 years of age, and rarely after 20 years of age.
Nerve root irritation is a common symptom. After the vertebral body slips forward, the intervertebral foramen is usually enlarged and the vertebral plate is left posteriorly, and the nerve roots are generally not disturbed. Nerve root compression can occur when the nerve arch is stretched and rotated around the small joint between the sacral bones, and the intervertebral foramen is invaded; the second type of nerve root invasion is when the proximal end of the isthmic fissure forms a hook-like osteophyte (sometimes called a mushroom cap-like osteophyte) that compresses the nerve root, which is more likely to be involved when the vertebral space narrows; in addition, the proliferating fibrocartilage at the site of the isthmic defect may also cause nerve root In addition, the nerve roots may be invaded by the proliferating fibrocartilage in the isthmic defect; eventually, the nerve roots may be involved by rupture of the slipped segment or other segments of the disc.
The nerve root penetrates the intervertebral foramen and enters the muscle with a more fixed stroke. In patients with lumbar spondylolisthesis, the vertebral body slides forward and downward along the sloping upper surface of the inferior vertebral body, especially at the L5-S1 segment, and the pedicle slides downward along the nerve root causing compression and intertwining with the nerve root that penetrates the intervertebral foramen.
Without disc degeneration there is no slippage of the vertebral body. Usually the degeneration is slowly progressive, sometimes the disc breaks down and bulges out of the circumference of the vertebral body like a painted putty in which the nerve roots can be encapsulated as they emanate from the foramen.
Below the transverse process and lateral to the vertebral body there are very strong ligamentous strips connected, called the transverse corporal ligament. At the level of L5, the fifth lumbar nerve travels between the ligament and the sacral wing, and when the L5 vertebral body slips forward and downward, the transverse corporal ligament cuts the lumbar 5 nerve root, causing it to latch on to the sacral wing. At the site of slippage, intrusion from the vertebral arch as well as from outside the intervertebral foramen can lead to nerve root compression; therefore, lumbar 5 vertebral body slippage usually involves the lumbar 5 nerve root.
The isthmic fracture of the vertebral arch predisposes to early degeneration of the underlying disc, and the slipped vertebral body eventually leads to disc degeneration. These degenerations themselves can lead to pain, causing localized or referred pain in the sciatic innervation area without radicular irritation.
Thus the causes of pain in the isthmic fissure of the vertebral arch, with or without slippage, include instability, intrinsic nerve root intrusion in the intervertebral foramen, extradural nerve root entrapment, and disc degeneration.
Second, the surgical treatment of lumbar isthmic spondylolisthesis slippage
Whether lumbar spondylolisthesis requires surgery is decided according to clinical symptoms. Its main manifestation is lower back pain and nerve root irritation symptoms. The purpose of surgery is to relieve the pain and release the nerve compression by decompression, repositioning, stabilization of the spine and fusion. It is important to accurately determine the cause, location and extent of the symptoms before surgery, and to focus on several steps such as decompression, fixation and fusion during surgery. Intermittent claudication is related to spinal stenosis; neuropathic paresthesia is related to lateral saphenous fossa stenosis and nerve root compression; and intractable low back pain is related to segmental instability. A reasonable surgical plan was developed based on the above clinical manifestations and then combined with relevant imaging examinations.
(I) Traditional surgical options
The traditional procedures include anterior decompression interbody implant fusion and posterior decompression intertransverse or intervertebral body implant fusion.
The anterior approach facilitates the exposure of the anterior spinal column, facilitates the removal of intervertebral discs, and has a large bone graft bed, which helps restore the physiological curvature of the lumbar spine. However, complications such as trauma and injury to the great vessels and sympathetic chain have prevented its widespread implementation.
The posterior approach allows clear visualization of degeneration and abnormalities of posterior spinal structures, such as small joint hyperplasia, degenerative degeneration, calcification of the posterior longitudinal ligament, and spinal stenosis, and allows simultaneous completion of spinal canal enlargement, decompression of the nerve root canal, transcatheter pedicle screw fixation, and bone grafting. However, there is a risk of nerve injury when performing anterior spinal cord operations, removing herniated discs, and performing intervertebral fusion.
Harms et al. modified the posterior interbody fusion by expanding the bone window outward to expose the entire posterior wall of the nerve root foramen, thus eliminating the need to overdraw the nerve roots medially when placing the fusion device and exposing only the unilateral nerve root foramen, reducing the strain on the spinal capsule, known as Transforaminal Lumbar Interbody Fusion (TLIF).
Lauber et al. reported 39 cases of mild lumbar spondylolisthesis with transforaminal interbody fusion, and the mean Oswestry dysfunction index decreased from 23.5 to 13.5 points, with a fusion rate of 94.8%, suggesting that transforaminal interbody fusion is a safe and effective method of interbody fusion. Houten et al. concluded that in the treatment of lumbar degenerative disc disorders, transforaminal interbody fusion treatment could achieve better results.
(ii) Recommended minimally invasive treatment strategies for lumbar spondylolisthesis
TLIF has been widely used clinically as a new type of lumbar fusion. Compared with other lumbar fusion procedures, TLIF enters the intervertebral space through the posterior lateral intervertebral foramen and completes the support of the anterior column while preserving the posterior dynamic tension structure, which has almost no effect on the mechanical load distribution of the spine and does not require excessive separation of the distraction dural sac and nerve roots during surgery, avoiding The postoperative epidural adhesions and scar formation are avoided, the possibility of intracanalicular plexus bleeding and nerve root injury is reduced, and the musculoligamentous structures of the lumbar region are better protected, which reduces surgical trauma and shortens the recovery time.
However, traditional posterior open surgery requires extensive stripping of the paravertebral muscles, which is highly traumatic to the tissue and may have an impact on the recovery and stability of the spine after spine surgery. In recent years, greater progress has been made in minimally invasive spine techniques. On the basis of open TLIF, Foley et al. first introduced the minimally invasive TLIF technique, in which an expandable cannula is inserted through the muscle gap and the operation of TLIF is completed within the cannula, which has the same advantages as open TLIF while minimizing medically induced soft tissue injury and reducing the loss of innervated muscle atrophy after lumbar back muscle stripping The clinical efficacy of TLIF is excellent, with less intraoperative bleeding, less postoperative pain and shorter hospital stay.
For the surgical treatment of lumbar spondylolisthesis, we recommend the use of minimally invasive TLIF for the release of mild to moderate lumbar isthmic spondylolisthesis.
From February 2004 to June 2008, we treated 21 cases of lumbar isthmic spondylolisthesis with minimally invasive TLIF under X-Tube, including 14 cases of I° slippage and 7 cases of II° slippage.
Procedure: After general anesthesia, the patient was placed prone on the surgical bed with soft pads on the chest and hip to avoid pressure on the abdomen, and the lumbar lesion was identified by C-arm fluoroscopy, marked on the body surface, and routinely disinfected and toweled. A longitudinal incision of approximately 2.5-3.0 cm in length was made in the posterior midline (determined by the preoperative CT scan), and the minimally invasive working tube was angled towards the superior edge of the disc, and the dilating catheter was inserted step by step, with the free arm fixed caudally to avoid interfering with the lateral X-ray fluoroscopy. Finally, an X-tube manipulation cannula is implanted and located at the small joint to prop up and remove the soft tissue from the small joint and the surface of the vertebral plate (Figure 13-2).
The fibrous scar tissue on the dorsal side of the isthmic fissure is removed, and most of the visible floating lamina and upper and lower articular processes are removed using a bone knife and lamina bite forceps or a grinding drill as bone graft material for backup, and the nerve roots are carefully exposed and loosened and protected, and the fall between the slipped vertebrae is detected on the lateral side of the dural sac, and the intervertebral disc is incised parallel to the direction of the intervertebral space, and an enlarged reamer is used sequentially to cut and separate the intervertebral disc and endplate cartilage with The intervertebral space is propped open until the anterior longitudinal ligament is partially torn, the disc is resected to the lateral aspect of the pedicle, and the free piece is removed with a nucleus pulposus forceps (Figure 13-3). Hemorrhage from the vertebral plexus can be stopped by bipolar electrocoagulation, gelatin sponge, and bone wax compression. After reamer release and bracing, the intervertebral mobility increases and it can be found that the slipped vertebral body has been partially repositioned. The pedicle screw is placed according to the anatomical landmarks, the appropriate fusion device Cage is selected, the intervertebral bone graft and Cage placement are performed, and the final pedicle screw is locked (Figure 13-4). Since the implantation of the Cage with the fixation of the pedicle screws affects the spinal sequence, it can be found that partial repositioning will still be obtained. Screws with a lifting effect are not used in this procedure (Figure 13-5). The intervertebral disc and isthmus are again explored and decompressed to ensure that no neural structures are compressed or present in tension. after the C-arm fluoroscopy is clear, the wound is flushed with 250 ml of saline plus 160,000 units of gentamicin, hemostasis is complete, negative pressure drains are left in place bilaterally, and sutures are placed layer by layer.
Figure 13-2 Implantation of X-tube operation cannula, removal of small joints, and
Figure 13-3 Removal of the free piece by nucleus pulposus forceps after reamer release of the intervertebral space
Soft tissue on the surface of the vertebral plate
Figure 13-4 A. L4-5 vertebral isthmus fracture slip; Figure 13-4B. Intraoperative fluoroscopic view showing Cage placement and arch fixation after release
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