Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6030_Библиотеки_им_академика_М_И_Перельмана.pdf
Figure 6–1
Lateral radiograph of a patient with cervical myelopathy due to cerebrospinal meningitis (CSM).
C4
C5
Spondylosis
C6
C7
Spinal
nerve root
Body
Cord
Lamina
OPLL or
spur
Figure 6–2
Magnetic resonance imaging (MRI) of a patient with cervical myelopathy due to CSM. Note that the compression is asymmetric to the left. Subsequent treatment will need
to specifically address the site of pathology.
■
30
SECTION I THE CERVICAL SPINE
Eurostile
C3
C1
C2
SCM
Trachea
C5
C6
C7
T1
Strap muscle
C4
Longus coli muscle
CC
IJV
SCM
Longitudinal
incision
Transverse
incision
Figure 6–3
Levels of approach and possible incisions.
Prevertebral
fascia
Superficial
fascia
Pretracheal
fascia
C6
A
Figure 6–4
(A,B) Axial schematics of the Smith-Robinson approach at the C6 level.
Eurostile
6 ANTERIOR CERVICAL CORPECTOMY
31
B
■
1.5 cm
Figure 6–5
Extent of decompression in cervical corpectomy. At least 1.5 cm of bone should be
resected as indicated by preoperative imaging findings.
A
Figure 6–6
(A) Decompression is complete. (B) Lateral view. Small angled rongeurs are used to perforate the end plates.
■
32
SECTION I THE CERVICAL SPINE
Eurostile
B
AB C
Figure 6–7
(A–C) Postoperative plain radiograph and drawings of a C5-C6 anterior cervical corpectomy with strut graft and anterior plate reconstruction.
Eurostile
Figure 6–8
Postoperative computed tomography (CT)-myelogram of an anterior cervical corpectomy and fusion (ACCF). Note the left-sided decompression.
6 ANTERIOR CERVICAL CORPECTOMY
33
■
7. Now, the carotid sheath and its structures may be gently retracted laterally with the SCM. Above C3–4, the superior thyroid arteries connect
the sheath to the midline structures. This limits the degree to which
this plane can be opened. Occasionally these vessels must be sacrificed for exposure; however, DO NOT divide the superior laryngeal
nerve that runs with these vessels.
8. Inferiorly, the ventral belly of the omohyoid is occasionally encountered. This structure may usually be retracted inferiorly; however,
no functional loss is associated with dividing it (especially if subsequently repaired). Further, the inferior thyroid artery and vein may
need to be retracted inferiorly or divided. If divided accidentally, the
inferior thyroid artery may retract behind the carotid sheath where it is
difficult to retrieve.
9. Next, a plane is developed deep to the cut pretracheal fascia by blunt
dissection (finger or Kidner). Proceed carefully medially behind the
esophagus. Soon, the cervical bodies should be visible, covered by longus colli and prevertebral fascia. The anterior longitudinal ligament
(ALL) is noted in the midline as gleaming white structure.
10. At this point, a 22-gauge needle is placed in the superior disc and a localizing radiograph is obtained.
11. This plane now exposes the prevertebral fascia, a firm, tough membrane in front of the prevertebral muscles on which the sympathetic
chain runs. This fascia is incised as the longus colli muscles are split
longitudinally with a Bovie. With a few millimeters of longus elevated
subperiosteally, rounded, hand-held retractors may be safely placed
under the muscle bellies.
Technique
1. With deep retractors in place under the longus muscles, anterior
osteophytes are resected with a Leksell rongeur. Then, discectomies
are performed above and below each intended corpectomy level with a
No. 15 blade through the ALL, anterior annulus, and anterior disc.
Then, a pituitary rongeur is used to remove superficial disc material. A
curet may be passed into the disc space to retrieve additional disc
material. We have not routinely completed the discectomy at this
point, as the additional exposure afforded by the vertebrectomy allows
a safer decompression. The disc margin and uncinate processes remain
significant landmarks for depth and laterality in the subsequent
decompression.
2. The corpectomy begins with a small rongeurs or high-speed bur to
create a trough in the body’s center. The necessary width of decompression can be estimated from preoperative studies. However, no less
than 1.5 cm of bone from the central body should be removed
(Fig. 6–5).
3. The corpectomy is carefully continued posteriorly to the level of the
posterior cortex. Intermittently, bone wax on a Penfield may be used to
stanch bleeding. Some authors recommend a diamond-tip bur at the
posterior cortex; we have not found this necessary. As the posterior
cortex is thinned, a small curet may be used to breech the cortex. This
small opening is gradually enlarged by elevating the thin flap of posterior cortex with a curet or fine Kerrison. This decompression is continued cranially and caudally to the adjacent disc spaces.
4. We typically undercut the superior and inferior margins of the adjacent bodies. Then, a fine nerve hook is used to assess the decompression. In the face of continued compression, the bone removal is continued. If there is a radicular component to the patient’s complaints,
the decompression is extended laterally to the disc space. Here, a fine
Kerrison or curet is passed into the foramen, allowing decompression
of the medial 1 to 3 mm of nerve root.
5. With the decompression complete, the defect must be prepared for stabilization. Careful end-plate preparation is critical. First, the end-plate
cartilage is removed with a curet. Although some authors recommend
burring the end plates to encourage fusion, this may result in collapse
of the graft. We recommend small, angled curets to perforate the end
plates (Fig. 6–6).
6. The intended strut graft is measure with the disc space distracted.
Such distraction may be obtained by a head halter, manually by anesthesia, or with a Caspar retractor. Overdistraction is to be avoided, as
it will change the weight-bearing characteristics of the cervical spine
and is associated with increased collapse of the graft.
7. Several different grafts and cage devices have been proposed for corpectomy defects. Most commonly, iliac crest or fibular struts are used.
Iliac crest may be used for up to a three-level corpectomy. Studies have
demonstrated that fibular struts are stronger in compression. Although
improved incorporation rates and times are reported for autograft, the
added morbidity of autogenous fibula harvest has led to an increase in
allograft fibula usage in recent years.
8. Several different graft geometries have been espoused as well. Most
commonly,a straight fibular strut is cut to length and tamped into position with 1 to 2 mm of countersinking. Some authors recommend purposely keying the graft into the cancellous bone of the bodies above
and below the corpectomy as a means of preventing extrusion. One elegant approach is the fibular H-graft of Whitecloud and LaRocca. Here,
the graft is notched at both ends. The middle thirds of the superior and
inferior vertebrae are perforated with a bur. Then, the fibular graft is
locked into the end plate at both ends. Regardless of the graft geometry
employed, careful measurement of depth will prevent graft encroachment on the canal.
Instrumentation may be added to increase fusion rates and postopera-
tive stability.
Advantages
1. A buttress effect to decrease graft migration.
2. Decreased graft collapse by load sharing.
3. Decreased postoperative immobilization with possible early return to
work and function.
4. Theoretically, fusion rates are improved.
Disadvantages
1. Additional operating room time and cost.
2. The potential for screw fracture or migration, which could lead to
esophageal erosion.
3. A possibly increased rate of infection.
The indications for plating remain controversial, but internal fixation
can be recommended in revision surgery, to obviate halo use in multiple
level corpectomy, and when bracing is impossible or unreliable (e.g., obese
patients). Closure is performed over a soft Jackson-Pratt drain with 2-0
Vicryl in the platysma followed by a 3-0 Vicryl subcuticular suture (Figs.
6–7 and 6–8).
Exposure Secrets
1. Careful attention to detail during the approach will afford significantly
improved ease and extent of exposure and thereby allow safer decompression and reconstruction. This attention begins with careful positioning. First, place a towel roll between the patient’s scapulae. Then,
ensure the neck is turned 15 degrees to the contralateral side. Slight extension is also helpful; however, in patients with significant canal stenosis, this should be avoided to prevent cord compression. Some find
that a horseshoe headrest allows the most accurate positioning of the
head. A reverse Trendelenburg position of 30 degrees reduces venous
bleeding and increases accessibility.
2. For radiographic visualization, especially in the lower cervical spine,
keep the arms at the sides (wrap the hands and protect the cubital tunnel). Then, secure the shoulders inferiorly with tape, but do not use too
much force because a brachial plexopathy may result. Alternatively, a
Kling roll may be tied around the wrists and traction applied at the
time of the radiographic exposure.
3. In thick-necked patients, a longitudinal approach allows for the addi-
tional extensibility that may be needed for visualization. Loupes and a
headlight or an operating microscope will further increase visualization. Undermining the platysma and complete fascial release aids in
deep dissection and manipulation.
4. Equal elevation of the left and right longus colli muscles for at least
one-half interspace above and below the intended discectomies allows
placement of a self-retaining retractor. This retractor may safely stay
beneath these muscle bellies during the procedure and affords excellent visualization. When the extent of decompression and reconstruction is longer, a second, self-retaining retractor (with blunt blades) may
be placed craniocaudally in the wound. During lengthy decompression procedures, these retractors should be removed at regular intervals to allow decompression of the soft tissue structures.
Pitfalls
1. Tightly stenotic patients are extremely prone to hyperextension cord
injuries while anesthetized and paralyzed. The utmost care in positioning and, often, fiberoptic intubation are required.
2. On the approach, carefully identify the carotid sheath, by palpation of
the pulse, prior to continuing the deep dissection. A nasogastric tube
will aid in identifying and preventing injury to the esophagus. Failure to
detect a laceration of the esophagus may result in dysphagia early. Later,
mediastinitus may ensue, with a high morbidity and mortality rate.
3. In the deep dissection, avoid injury to the discs of adjacent levels.
Also, overstretching the longus muscles may result in injury to the cervical sympathetic chain and a postoperative Horner’s syndrome.
■
34
SECTION I THE CERVICAL SPINE
Eurostile
4. It is important to be cognizant of the midline at all times. Drifting laterally may injure the vertebral arteries. During the decompression, identify the uncovertebral joints as a guide to the lateral aspect of the disc
space. Also, the lateral aspect of the body may be palpated with a Penfield or similar probe.
5. During the insertion of the bone graft, maintain a Kocher or similar
clamp on the strut graft during insertion/tamping. Also, during initial
placement, spanning the graft and the adjacent, intact body with the
tamp will prevent overdeep insertion and spinal cord injury.
Complications
1. Complaints surrounding the graft harvest site are the most common
after anterior fusion procedures. These problems include pain, infection, ilium fracture, and lateral femoral cutaneous nerve palsies. Next,
a transient sore throat or difficulty swallowing is reported.
2. Esophageal and tracheal injuries are uncommon, but can be avoided
with careful retractor placement.
3. Vocal cord paralysis is reported in up to 11 % of cases but is usually
temporary and unilateral. Laryngoscopy to assess vocal cord motility
may be indicated if there has been no improvement at 6 weeks.
4. Horner’s syndrome, from injury to sympathetic chain, usually via overretraction on longus colli, presents with ptosis, miosis, and anhidrosis.
5. Anterior decompression procedures may be associated with neurologic injury and cerebrospinal fluid (CSF) leak. The incidence has been
reported at 1 % overall. Transient C5 root injury is the most common.
However, devastating spinal cord injuries are also reported. It is crucial not to attempt to reach around the back of the superior or inferior
body to remove additional osteophytes. Rather, extend the corpectomy
to the next level cranially or caudally as needed.
6. Loss of stability of the reconstructed spine from angulation of the graft
is also reported. In long strut fusions, this may result in airway obstruction or spinal cord compression.
7. Lundsford reported a 1.4 % incidence of wound infection at the neck
and another 1.4% incidence at the graft harvest site.
8. Adjacent segment degeneration may be seen in 25% of patients within
10 years. This phenomenon may be particularly common in older
patients with preexisting degeneration or in fusions ending at C5 or C6.
9. Vessel injury is less commonly reported but may include the carotid
sheath and contents, which are usually protected by anterior border of
SCM. Injudicious placement of self-retaining retractors may endanger
the sheath. Overretraction on hand-held retractors may also have dire
consequences. As mentioned above, the vertebral artery is vulnerable
if the decompression strays laterally. The thoracic duct is vulnerable at
the cervicothoracic junction on the left side.
Postoperative Care
1. The patient may be out of bed the evening of surgery. Early ambulation
is encouraged.
2. A drain is routinely left in the deep space of the neck. This drain is removed once its output is less than 10 cc per 8-hour period, and the
patient is successfully ambulating and tolerating a regular diet.
3. In most patients, we use a firm collar postoperatively for 6 to 12 weeks.
In patients reconstructed with a strut and anterior cervical plate, the
collar is often discontinued earlier, at 2 weeks. The patient generally
wears the brace full time, except when showering. In patients with
longer strut fusions or marked osteopenia, a halo or posterior stabilization may be required.
4. Routine radiographic examination of the healing graft site is undertaken at 2 weeks and 8 weeks, and at 6 and 12 months.
Suggested Readings
Bernard TN, Whitecloud TS. Cervical spondylotic myelopathy and my-
eloradiculopathy: anterior decompression and stabilization with autogenous fibula strut graft. Clin Orthop 1987;221:149–160.
Bohlman H. Cervical spondylosis with moderate to severe myelopathy.
Spine 1977;2:151–162.
Emery SE. Anterior approach for cervical myelopathy. In: Clark CR, ed.
The Cervical Spine. 3rd ed. Philadelphia: Lippincott-Raven; 1998:825–
837.
Emery SE, Bohlman HH, Bolesta MJ, Jones PK. Anterior cervical dis-
cectomy and arthrodesis for the treatment of cervical spondylotic myelopathy: 2–17 year follow-up. J Bone Joint Surg Am 1998;80:941–951.
Fernyhough JC, White JI, LaRocca H. Fusion rates in multi-level cervical
spondylosis comparing allograft fibula with autograft fibula in 126
patients. Spine 1991;16(suppl):S561–S564.
Herkowitz H. The surgical management of cervical spondylotic
radiculopathy and myelopathy. Clin Orthop 1989;239:94.
Kurz LT, Herkowitz HN. Surgical management of myelopathy. Orthop Clin
North Am 1992;23:495–504.
Whitecloud T, LaRocca H. Fibular strut graft in reconstructive surgery of
the cervical spine. Spine 1976;1:33.
Zdeblick T, Bohlman H. Myelopathy, cervical kyphosis and treatment by
anterior corpectomy and strut grafting. J Bone Joint Surg Am
1989;71:170.
Eurostile
6 ANTERIOR CERVICAL CORPECTOMY
35
■
7
Multiple-Level Cervical Vertebrectomy
(Corpectomy) and Stabilization Using
Cortical Bone
Thomas S. Whitecloud III and Orderia Mitchell
Goals of Surgical Treatment
Directly decompress the cervical spinal cord and stabilize the cervical
vertebral column after decompression.
Diagnosis
Cervical myelopathy secondary to cervical cord compression can occur
due to congenital narrowing, cervical spondylosis, tumor, or trauma. The
diagnosis is made by physical examination, plain x-rays, magnetic resonance imaging (MRI), and/or myelo/computed tomography (CT).
Indications for Surgery
1. Cervical spondylotic myelopathy
2. Multiple levels for stabilization
3. Tumors
4. Trauma
Positioning
Correct preoperative positioning is essential.
1. Supine with neck in the neutral position (Fig. 7–1).
2. Head halter or skeletal traction is applied.
3. Cervical traction with 10 lbs (fractures may require less traction).
4. Obtain anteroposterior (AP) and lateral views of the spine to assure
correct position of the vertebral column.
Incision Options
1. Transverse
2. Oblique
It is possible to expose up to three levels through a horizontal skin incision, but the amount of retraction necessary for this exposure is sometimes
excessive and can be difficult in larger patients. The incision we prefer is
an oblique incision along the medial border of the sternocleidomastoid on
the patient’s right side (Fig. 7–2). The incision can be extended superiorly
to the level of the vertebral body of C2 and inferiorly to the body of C7 and
the C7-T1 disc space.
Dissection
After the skin incision is made and the incision is carried down to the level
of the platysma muscle, the platysma is incised in line with the incision.
This is followed by identification of the medial border of the sternocleidomastoid muscle, which is mobilized through the length of the skin incision to maximize soft tissue relaxation. The interval between the carotid
sheath, esophagus, and trachea is identified and developed. Blunt dissection is performed through this interval, gently dissected proximally and
distally. Dissection is performed using a single digit, a Kitner, or blunt instrument. Care is taken not to injure the neurovascular structures laterally
or the esophagus and trachea medially. Dissection is carried down to the
anterior portion of the cervical spine. Blunt retractors are placed, which allows excellent exposure with little danger of injury to the carotid sheath or
esophagus. The precervical fascia is exposed and incised. The anterior portion of the vertebral column is now exposed. The longus colli muscles are
identified and elevated laterally. Hemostasis is achieved as this process is
performed. Self-retaining blunt retractors are inserted (Casper), further exposing the anterior column. It is important to obtain hemostasis as the exposure proceeds, allowing better visualization of the operative field.
Points of Interest
1. Blunt dissection decreases the chance of soft tissue injury.
2. Following the fascial planes minimizes injury.
3. It may be necessary to release the omohyoid muscle.
4. Headlight illumination allows excellent visualization of the operative
field. Magnification with loupes or the operative microscope should be
utilized.
5. Retraction can be performed using a blunt self-retaining retractor,
which provides better soft tissue protection.
Decompression
Prior to decompression a needle is placed for verification of the respective
disc space level and center of the vertebrae. After identification of the correct levels using radiographic control, discectomies are performed. Removal of the disc material first facilitates a later corpectomy. Disc excision
should be done to the level of the uncinate processes bilaterally. Removal
of posterior osteophytes should not be attempted until vertebrectomy has
been performed.
Vertebrectomy (Corpectomy)
Vertebrectomy/corpectomy is performed after removal of the disc. A
trough is made in the anterior aspects of the intervening vertebral body
using a large rongeur (Fig. 7–3). The trough is widened to an approximately
12-mm width in the center of the vertebral body. In the case of tumor, all of
the involved vertebral bodies are removed back to the spinal cord. For fractures, compressive lesions are also removed back to the spinal cord. Hemostasis can be obtained by the use of bone wax and done at one level
while decompressing another level. Bleeding is usually due to segmental
vessels entering the center of the vertebral body. The trough is gradually
deepened using both a large rongeur and large curet (Fig. 7–4). Once the
trough is deepened approximately three fourths of the depth of the vertebral body, a power bur is used to remove the remaining portion of the cancellous body. Removal of the posterior cortical bone is performed with a diamond-tipped bur. When the posterior wall is thinned, a small-angle curet
or a small rongeur can be used to remove the remainder of the posterior
wall and any osteophytes located at disc level. The lateral recesses are
decompressed by undercutting the edges of the vertebral bodies bilaterally.
If most of the compression occurs at the disc level, which is secondary to
posterior and posterior lateral osteophytes, the compressive structures are
best removed from the middle portion of the vertebral body rather than at
disc level. The compressive structures are readily visualized and it may be
safer to remove them in this manner.
Allograft Selection and Preparation
The graft of choice is a fibular allograft. It is slightly longer than the trough
usually by a length of 5 to 8 mm. The width of the fibular strut should be as
wide as possible. Parallel notches should be made at each end of the graft
using a power bur (Fig. 7–5). Insertion of the graft should be performed
placing the widest portion of the graft in the trough seated against its lateral
borders. In the case of tumors, there may be no lateral walls for seating of
the graft, only inferior and superior notches. The preparation of the undersurface of the vertebral body is performed by undercutting the inferior and
superior end plates with a bur. This undercutting is done by approximately
one fourth of the depth of the body. The holes are made wide enough to accept the graft using a curet. Care should be taken not to violate the anterior
edges of vertebral end plates.
After the patient’s vertebral bodies and allograft have been prepared,
the superior end of the graft is inserted first (Fig. 7–6). Cervical traction is
applied and the inferior end is seated. Release of traction allows the graft to
be seated. At this time, imaging confirms the graft position. It is important
to ensure that the graft is well seated in the superior and inferior vertebrae
(Fig. 7–7). When the patient is positioned upright, additional seating of the
strut graft occurs due to loading. This causes further locking of the graft
into position (Fig. 7–8).
Complications
1. Dislodgment of the graft
2. Transient dysphasia
3. Esophageal injury
4. Hoarseness
Dislodgment of the graft is usually due to the graft being too short and
not locking in place or fracture of the superior edge of the inferior vertebrae. If this occurs, a longer graft needs to be inserted or the undercut portion of the inferior vertebrae made deeper. Inserting a longer graft usually
provides a stable construct. Transient dysphasia and esophageal injury can
■
36
SECTION I THE CERVICAL SPINE
Eurostile
C1
C2
Skin incision
C4
C3
C5
C6
C7
Figure 7–1
Positioning of patient.
Figure 7–2
Incision.
A
Figure 7–3
(A,B) Vertebrectomy.
Eurostile
7 MULTIPLE-LEVEL CERVICAL VERTEBRECTOMY (CORPECTOMY)
37
B
■
Figure 7–4
(A,B) Interoperative trough/vertebrectomy.
Figure 7–5
Graft preparation.
Figure 7–6
Graft placement.
Figure 7–7
Graft in place.
■
38
A
Figure 7–8
X-rays of the graft at surgery (B), and graft locked in place after the patient is positioned upright (A).
SECTION I THE CERVICAL SPINE
Eurostile
B
be minimized by blunt dissection and gentle retraction. Protection of the
esophagus, trachea, and vascular structures using blunt retractors minimizes injury. Transient dysphasia can be improved by releasing the retractors when possible. Hoarseness can occur but usually is transient in nature.
Care must be taken when dissecting at C6 and below to avoid injury to the
recurrent laryngeal nerve.
Postoperative Care and Management
Most patients are treated with a Philadelphia collar. Exceptions are
tumors, trauma patients, or patients who are severely osteopenic. A Halo
vest may be necessary in these individuals. Dislodgment of the graft or
swelling usually occurs within the first week after surgery. The graft usually dislodges at the anteroinferior aspect of the lowermost vertebral body
and usually is associated with a fracture of the edges of the lower vertebral
body. Management has been described. The patient is usually maintained
in a hard cervical collar or halo for approximately 8 to 12 weeks. During
this time, the patient undergoes rehabilitation as required.
For one- or two-level pathology, an autogenous iliac crest graft can be
utilized. It is recommended that if there are more than two vertebral bodies
removed, a cortical graft should be used because of the increased resistance
to friction.
Points of Interest
1. Identification of correct levels and center of the vertebral body by
using a spinal needle in the disc space and radiographic control.
2. Hemostasis.
3. Spinal cord decompression should begin at the midportion of the
vertebral body.
4. Preparation of the allograft fibula using a bur, not an osteotome or
rongeur.
5. Use of a wide blunt retractor minimizes soft tissue, vessel organs, and
vessel injury.
Suggested Readings
Bailey RW, Badgley CE. Stabilization of the cervical spine fusion. J Bone
Joint Surg 1960;42:565.
Bernard TN Jr, Whitecloud TS III. Cervical spondylotic myelopathy and
myeloradiculopathy: anterior decompression and stabilization with
autogenous fibula strut graft. Clin Orthop 1987;221:149–160.
Bohlman HH. Cervical spondylosis with moderate to severe myelopathy: a
report of 17 cases treated by Robinson anterior cervical discectomy
and fusion. Spine 1977;2:151–162.
Eurostile
7 MULTIPLE-LEVEL CERVICAL VERTEBRECTOMY (CORPECTOMY)
39
■