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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6032_Библиотеки_им_академика_М_И_Перельмана
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fibers to expose the underlying rib and intercostal space. If the affected level
is above T7, the ventral edge of the latissimus dorsi is retracted or incised.
30
The thoracotomy can be performed through a rib-sparing approach in which
the intercostal spaces are elevated off the rib or by resecting a portion of the
rib directly over the appropriate spinal level.30 After rib resection or
retraction, the pleura is incised and single-lung ventilation is initiated. The
anesthesiologist generally reduces inspiration volume before the pleural
incision to avoid inadvertent injury to the lung. Self-retaining rib retractors
enable clear visualization of the lateral aspect of the spine. A spinal needle is
inserted into the disk space and radiography is used to confirm the target
spinal level. With this approach, the anterolateral circumference of the
thoracic vertebra can be visualized. Segmental vessels can be ligated or
clipped and cut if vertebral body access is needed. A radiolucent sponge is
placed anterior to the spine to protect the aorta during the remainder of the
surgical procedure.
29,30
Advantages and Limitations
Minimally invasive thoracotomy is less technically demanding than closed
thoracotomy and results in less blood loss and faster patient recovery
compared with procedures using a larger thoracotomy incision. However,
there is a substantial learning curve among surgeons not familiar with
transthoracic approaches and those unaccustomed to working without the
assistance of a thoracic surgeon. Also, some patients may be unable to
tolerate single-lung ventilation.
Posterior Midline Approach to the Thoracolumbar Spine
The posterior midline approach is perhaps the most common approach used
by spine surgeons in routine practice. This approach provides direct
visualization of the spinous process, laminae, pars interarticularis, facet
joints, transverse process, and pedicles. It can be used to perform diskectomy,
direct decompression, osteotomies, and posterior interbody fusion and to
place pedicle screws and cortical screws.
Patient Position
The posterior midline approach is performed with the patient prone on a
spinal frame, with the abdomen hanging freely to decrease blood loss.
Fluoroscopy can be used to mark the target level before the skin incision is
made. The skin and subcutaneous tissue are infiltrated with 1:500,000
epinephrine, which may help in hemostasis.
Surgical Steps
A midline skin incision corresponding to the target vertebrae is performed,
and further dissection down the midline is accomplished using electrocautery
to reach thoracolumbar fascia, which are incised in line with the skin incision.
Cerebellar or Gelpi retractors are used to help maintain sufficient tissue
tension during exposure. The tendinous attachments of muscles over the
spinous process are released, followed by subperiosteal exposure of the
lamina of interest using a Cobb elevator. The procedure is repeated until all
target vertebrae are exposed. This procedure can be performed unilaterally or
bilaterally, depending on surgical indications. At this point in the procedure,
the paraspinal muscles can be held laterally with self-retaining retractors.
Exposure lateral to the facet joints can be accomplished if pedicle screws are
planned or access to the intertransverse region is desired for bone graft
placement. When using conventional pedicle screws, the multifidus tendons
can be released from the lateral facet capsule with electrocautery. This
facilitates gentle retraction of the muscles lying over the transverse processes,
which can be elevated rather easily with a Cobb elevator. Care should be
taken around the superior and inferior margins of the facet because arterial
perforators can be a nuisance if not recognized and cauterized. For pedicle
screw placement through the cortical bone trajectory, the exposure only needs
to reach the lateral aspect of the pars interarticularis. This spares the muscle
attachments along the lateral facet joint, which aids in achieving a minimally
invasive midline dissection. After the desired procedure is completed, the
muscle, fascia, subcutaneous tissue, and skin are closed in individual layers.
Advantages and Limitations
Advantages of the posterior midline approach are surgeon familiarity, clear
appreciation of the anatomy, and little or no risk of neurovascular injury.
Limitations include possible excessive blood loss, extensive soft-tissue
damage, and severe postoperative pain.
Lateral Lumbar Interbody Fusion
Lateral lumbar interbody fusion (LLIF) is a general term given to evolving
methods of less invasive access to the lateral aspect of the spinal column via
a retroperitoneal approach with the patient in the lateral decubitus position.
Two types of LLIF have been described—direct (look) lateral interbody
fusion (DLIF) and extreme lateral interbody fusion (XLIF).
31-36
XLIF was originally described as a two-incision technique in which the
first incision is made just lateral to the paraspinal muscles and a second
incision is made in the midaxillary line.31 The first incision allows the
surgeon to mobilize the peritoneum away from the percutaneous application
of tubular retractors that are inserted through the second incision.31 As
originally described, the tubular retractors are placed directly through the
psoas muscle to dock onto the disk of interest.
In the DLIF technique, a single incision is made in the midaxillary line;
often this incision is longer than that used in XLIF to allow the surgeon to
directly look at the muscle layers and deep surgical anatomy.
33,34
The DLIF
technique allows the surgeon to directly visualize the psoas muscle and place
retractors anterior to rather than through the muscle. By directly visualizing
the anatomy and approaching the spine anterior to the psoas, the DLIF
technique may reduce injury to the lumbosacral plexus. This type of injury
has been reported with the XLIF technique.
34
Appropriate Levels
Lumbar levels from L2-L3 and L3-L4 can be accessed through LLIF, but L4L5 and L5-S1 are difficult to approach secondary to the iliac crest. Some
authors report that L4-L5 can be approached through increased lateral flexion
of the patient, but the risk of L4 nerve injury should also be considered in
preoperative planning and intraoperative execution.
32-34
The approach to
levels above L2 is challenging because the ribs tend to deflect the retractors
away from optimum disk access. In addition, the diaphragmatic crus or
diaphragm itself may inhibit access in this region. Transdiaphragmatic access
is possible; however, the surgeon should be prepared to place a chest tube in
this setting.
Positioning and Neuromonitoring
LLIF is performed with the patient in the lateral decubitus position to avoid
injury to the inferior vena cava and allow the peritoneum to fall anterior and
away from the surgical trajectory. The use of an adjustable table with a break
placed at the disk space of interest (especially at lower lumbar levels and
thoracolumbar levels) may facilitate safe access. Care should be taken to flex
the ipsilateral hip, which may help in mobilization of the psoas without
putting unnecessary pressure on the lumbar plexus during retractor
placement. Intraoperative neuromonitoring and directional electromyography
(EMG; free-run EMG through the dilators, which can be rotated) has been
advocated to reduce plexus injury related to retractor placement.
35
Surgical Steps
The correct level is identified through biplanar fluoroscopy or navigation, and
a marking is placed on the flank corresponding to the center point of the
targeted disk space. A 3-cm incision is placed on the left flank, and
electrocautery is then used to cut through the external oblique fascia.
31,32
Depending on the number of affected levels, the skin incision can be
extended. Blunt dissection with a finger or peanut is used to reach the
retroperitoneum through the external oblique, internal oblique, and transverse
abdominis muscles. Branches of the subcostal iliohypogastric and ilioinguinal
nerves may be encountered either running freely in the retroperitoneum or,
more commonly, between the internal oblique and transversus abdominus.
37
Abdominal wall denervation and dermatomal pain can occur if these branches
are not protected. To reach the psoas, dorsal to ventral blunt dissection is
used to move the peritoneum away from the surgical plane. Before passing
through the psoas, the anterior vessels and posterior lumbar plexus are
checked. To ensure their safety, the psoas should be separated between the
middle and anterior third of the muscle, and the abdominal contents along
with peritoneum are protected by placing handheld retractors. After the psoas
muscle is visualized, sequential tubular dilators are passed through the
muscle to reach the disk space. Dilators are rotated 360° while stimulating
EMG leads to assess the proximity of the lumbar plexus.
35
Complications
The most commonly observed complications of this approach (with a
reported incidence of 0.7% to 19.7% during long-term follow-up) are anterior
thigh numbness and hip flexor weakness.36 Vascular injury is uncommon, but
it can be life-threatening because lateral positioning places barriers to and
allows minimal access for timely vascular repair.
38
Oblique Lumbar Interbody Fusion
Oblique lumbar interbody fusion (OLIF) is an alternative to LLIF. A
retroperitoneal approach to the lumbar spine from L5-S1 to L1-L2 is
achieved through a single skin incision. Advantages of OLIF over DLIF and
XLIF are a decreased risk of neurologic injury and improved access to the
L4-L5 and the L5-S1 levels.
39
Positioning and Neuromonitoring
OLIF is performed with the patient in lateral decubitus position on a Jackson
frame. Lumbosacral plexus injury risks are lower compared with XLIF, and
the routine use of EMG neuromonitoring is less common.
39-41
Surgical Exposure
The center point of the targeted disk space is marked under fluoroscopy. For
a single level, OLIF uses an incision similar to that used in XLIF; however, it
starts at the anterior edge of the disk (localized fluoroscopically) and extends
3 to 4 cm anteriorly in line with the disk. For multilevel procedures, an
oblique skin incision of 5 to 10 cm is created in line with the fibers of the
external oblique muscle along the lateral wall of the abdomen. The incision
can be curved anteriorly along the anterior border of the anterior superior
iliac spine (ASIS) and approximately 5 to 8 cm anterior to the anterior margin
of the vertebral body39 (Figure 4). Abdominal muscles can be bluntly
separated with minimal cautery after dividing their fascia. The peritoneum is
separated from underlying retroperitoneal structures by blunt finger
dissection, and the abdominal contents are retracted anteriorly. The psoas
muscle and the genitofemoral nerve are visualized, and the targeted disk
space is then approached between the left psoas and the aorta. A spinal
needle or Kirschner wire is placed in the disk space to confirm the surgical
level fluoroscopically. The left-sided ureter and the sympathetic chain are
mobilized anteriorly. In initial reports of this technique, the iliolumbar veins
were not routinely ligated because the approach to the L4-L5 disk is lateral or
anterolateral as opposed to directly anterior as performed in the anterior
lumbar interbody fusion technique. This modification requires less retraction
of the great vessels. Importantly, when approaching the L5-S1 level, the disk
is removed lateral to the common iliac vessels rather than in the bifurcation.
Retraction of the peritoneum and vessels can be performed either with
handheld retractors or using sequential dilators and self-retaining retractors as
described previously in LLIF exposures.
39
Complications
Complications of OLIF include ureteral injury, neurologic injury, and
transient psoas weakness.
41
Minimally Invasive Transforaminal Lumbar Interbody Fusion
The minimally invasive transforaminal lumbar interbody fusion (TLIF)
technique has become increasingly popular because of the perceived
advantages of preserving the posterior osteoligamentous (supraspinous and
interspinous ligaments) tension band and the need for less retraction of
lumbar multifidus muscles.
42-44
Disadvantages include a substantial learning
curve, increased ionizing radiation exposure to the patient and staff, and
reported increased risks of nerve root injury.
43
Surgical Steps
The patient is placed prone on a Jackson frame and the affected spinal level is
identified fluoroscopically. Guidewires are inserted into the pedicles via 1- to
2-cm paramedian incisions, and cannulated pedicle screws are placed over
the guidewire. Performance of TLIF on the more symptomatic side is
recommended. If substantial symptoms are present bilaterally, the
contralateral side can be directly decompressed by depressing the thecal sac
anteriorly and “crossing over” to the other side and performing the
decompression. This decompression is technically demanding. If a durotomy
occurs, it may not be repairable using this approach. Sequential soft-tissue
dilators are then docked on the intervening facet and expanded to a desired
working diameter of approximately 24 to 28 mm. Various additional
retractors can be inserted over the tubular retractors to allow even greater
visibility. The decompression of the lateral recess and foramen is performed
Figure 4
through the ipsilateral facet and pars interarticularis. Contralateral
decompression of the spinal canal can be performed by angling the retractor
blades to the opposite side or by inserting the retractor on the contralateral
side and repeating this step.42 Bayoneted Kerrison and pituitary rongeurs can
assist in decompressing the neural elements. Distraction of the pedicle screws
allows for greater interpedicular access to the disk for TLIF. Pedicle screws
are placed in a percutaneous fashion on the contralateral side to complete the
construct.
42
Schematic drawings depict the sequential layers of the
surgical exposure for oblique lateral interbody fusion. A,
With the patient in the lateral decubitus position, the skin is incised in
diagonal fashion just proximal to the iliac crest. Below the
subcutaneous fat, the external oblique muscle is encountered and can
be divided parallel to the muscle fibers (dotted line). B, Below the
external oblique muscle, the internal oblique muscle is encountered
and can be divided parallel to the muscle fibers (dotted line). C, Below
the internal oblique muscle, the transversalis fascia is encountered
and can be divided in line with the skin incision. Below the
transversalis fascia lies the retroperitoneal fat. D, The retroperitoneal
contents are gently retracted anteriorly to expose the psoas muscle
and anterolateral aspect of the lumbar spine.
Complications
Complications associated with minimally invasive TLIF are incidental
durotomy, implant malposition, neural injury, and nonunion.
Anterior Lumbar Interbody Fusion
Anterior lumbar interbody fusion approaches the disk space from a nearly
direct anterior retroperitoneal approach. Because this procedure provides
wide access to the disk space, it can be used to treat a vast spectrum of
conditions, including degenerative conditions, deformities, spondylolisthesis,
and failed posterior surgery (such as pseudarthrosis).
45-48
Surgical Exposure
Anterior lumbar interbody fusion is performed with the patient supine. To
facilitate natural lumbar lordosis, a roll or a bump is placed under the lumbar
spine. A vertical, paramedian skin incision may be needed for multiple levels;
however, a low transverse Pfannenstiel incision can be used for exposure to
L5-S1 and sometimes for L4-L5.48 A left-sided retroperitoneal dissection
allows easier dissection of the inferior vena cava. After the skin incision,
further dissection through the fatty layer is performed using electrocautery to
reach the anterior layer of the rectus sheath, which is then incised vertically.
The peritoneum is separated using blunt finger dissection to create the
retroperitoneal plane. The peritoneum is retracted from the left side toward
the center using handheld retractors to reach the anterior surface of the great
vessels. Dissection is performed anterior to the psoas muscle; care must be
taken to preserve the genitofemoral nerve, which lies on the anterior surface
of the psoas. Each anatomic level has a different relationship to surrounding
neurovascular structures.48 At the L5-S1 disk level, the disk space is
approached between bifurcation of the common iliac vessels, which are
retracted laterally.48 Care should be taken to ligate the middle sacral vein.
Bipolar cautery is recommended to reduce the risk of presacral plexus injury,
which can lead to sexual dysfunction, particularly retrograde ejaculation. At
L4-L5, the left-sided common iliac vessels lie on the anterior surface of the
disk. Typically, these vessels are retracted from left to right. When
mobilizing the iliac veins, ligation of the iliolumbar vein may prevent traction
to the right iliac vein during mobilization. Vertebral body osteophytes may
obstruct vein mobilization. Obtaining a subperiosteal plane can facilitate vein
mobilization around adherent osteophytes. At the L3-L4 disk level and
higher, the inferior vena cava and the aorta are more easily mobilized to the
patient’s right side.
Complications
The most common specific complications of the anterior lumbar interbody
fusion approach include bowel perforation, ureteral or bladder injury,
vascular injury, retrograde ejaculation, deep vein thrombosis, and
retroperitoneal hematoma resulting from failed hemostasis.
46
Wiltse Approach
The Wiltse approach, also known as the paraspinal approach, is indicated for
far lateral disk herniation, posterolateral bone grafting for fusion in situ, and
pedicle screw placement.
Surgical Exposure
The Wiltse muscle-splitting approach involves the intermuscular plane
between the multifidus and longissimus muscles.49 The correct level is
identified by placing a spinal needle in the paraspinal area corresponding to
the intended disk level and confirming the position fluoroscopically. A
vertical skin incision of 3 to 4 cm is made approximately 3 cm lateral from
the midline. In thin patients, the intermuscular septum between the multifidus
and longissimus can be palpated, and the incision is made directly over this
septum. The deep fascia is identified and incised vertically. The septum
between the longissimus and the multifidus is identified, and a second fascial
incision is then made in the lateral most aspect of the multifidus. This allows
gentle retraction of the multifidus toward the midline. Blunt, handheld
appendiceal retractors can be helpful. Blunt finger dissection through the
fatty plane between the multifidus and longissimus muscles is performed
until the lateral aspect of the facets and the cephalad and caudal transverse
processes can be palpated. After the lateral aspect of the facet joint is clearly
visualized, a bipolar cautery facilitates release of the multifidus attachments
from the facet. A Penfield No. 4 retractor is used to strip muscle from the
cephalad and caudal transverse processes, thereby exposing the
intertransverse membrane. The septum is then released from the medial
superior border of the caudal transverse process and reflected proximally and
laterally. Frequently, a facet bleeder will require coagulation during this
maneuver. A Penfield No. 4 retractor also is used to mobilize perineural fat to
expose the far lateral herniated fragment and the exiting nerve root. Most
commonly, the nerve root is most easily mobilized cranially.
Advantages and Limitations
The Wiltse approach requires less bone removal than the conventional
midline approach to treat lateral and far lateral disk herniations. The approach
also allows clear visualization of the neuroforaminal and extraforaminal
areas. Although the Wiltse approach is more appropriate for far lateral disk
herniations, it becomes more challenging to use at the lower spinal levels,
especially L5-S1, because of close approximation of the L5 transverse
process and the sacral ala.49 Other limitations include bleeding from
surrounding muscles, injury to the nerve root, and difficulty in enucleating
the disk.
50,51
Bone Grafting
Autologous iliac bone graft is preferred for use in spine fusion. It is strongly
recommended that spine surgeons have a working knowledge of the
technique of obtaining graft from the anterior and posterior iliac crests. Both
the anterior and posterior ilium are potential sources for cancellous, cortical,
or combined bone graft; however, in terms of volume, bone graft of maximal
quality can be obtained from the posterior iliac crest.
Posterior Iliac Bone Graft
Posterior iliac bone graft can be obtained through the same skin incision as
used in the index spine procedure or through a separate skin incision. Using
the same midline posterior incision to approach the posterior iliac crest is
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