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_6013_Библиотеки_им_академика_М_И_Перельмана.pdf
Procedure 21 | VEPTR Opening Wedge Thoracostomy for Congenital Spinal Deformities 207
1st rib
FIGURE 21-25
E X PA NS I O N P E A R L S
• Distraction of the devices should be
slow. When there is excessive reactive
force within the first 5 mm of
expansion, the distraction forceps are
locked by the nut on the handles, and
a relaxation period of 3 minutes is
allowed to enable the chest wall tissues
to accommodate the distraction and
the reactive forces to dissipate. Another
distraction of 2 to 3 mm is then
performed. The cycle is repeated until
the reactive force is consistently large,
and then the distraction lock is placed.
• With the VEPTR II in those patients with
kyphosis, the surgeon may consider
accessing the proximal rod through a
separate incision to gently straighten
it with in situ benders to provide
corrective force for the kyphosis in
addition to expanding the device.
E X PA NS I O N P I T F A L LS
• Overdistraction, forcing the devices into
greater length even when there is large
reactive force, will cause breakage of
the ribs of attachment and should be
avoided.
• The goal of an expansion surgery is to
take the slack out of the system, not
correcting further deformity.
Replacement Procedure
n
When devices are completely expanded and the patient is still growing, a
change to a longer size is warranted.
n
In an outpatient setting, using a general anesthetic, limited skin incisions are
made over key areas. For the hybrid devices, the rib sleeve–superior cradle junction, the distraction lock of the rib sleeve, and the hook are accessed through
separate incisions. For rib-to-rib devices, the rib sleeve–superior cradle junction,
the distraction lock of the rib sleeve, and the distal end of the inferior rib cradle
are accessed. The devices are unlocked by removal of the distraction locks and
the cradle end locks, and loosening of the hook. The old devices are removed
through the inferior incisions. Longer devices, appropriate for the new length,
are inserted and then distracted to tension the construct.
n
Wounds are closed in the usual fashion, and postoperative care is similar to
that for the expansion procedure.
Evidence
Campbell RM, Hell-Vocke AK. Growth of the thoracic spine in congenital scoliosis
after expansion thoracoplasty. J Bone Joint Surg Am 2003;85:409-20.
Campbell RM Jr, Smith MD. Thoracic insufficiency syndrome and exotic scoliosis.
J Bone Joint Surg Am 2007;89(Suppl 1):108-22.
Campbell RM, Smith MD, Hell-Vocke AK. Expansion thoracoplasty: the surgical
technique of opening-wedge thoracostomy. Surgical technique. J Bone Joint
Surg Am 2004;86(Suppl 1):51-64.
Campbell RM Jr, Smith MD, Mayes TC, et al. The characteristics of thoracic
insufficiency syndrome associated with fused ribs and scoliosis. J Bone Joint Surg
Am 2003a;85:399-408.
Campbell RM, Smith MD, Mayes TC, et al. The effect of opening wedge
thoracostomy on thoracic insufficiency syndrome associated with fused ribs and
congenital scoliosis. J Bone Joint Surg Am 2003b;85:1615-24.
P R O C ED U R E 2 2
Posterior Thoracolumbar
Fusion Techniques
for Adolescent
Idiopathic Scoliosis
Coleen S. Sabatini and David L. Skaggs
I N D I CAT I O NS P I T F A L L S
• Don’t miss an underlying diagnosis;
remember that idiopathic scoliosis is a
diagnosis of exclusion.
• If there is abnormal pain or any
neurologic signs or symptoms, magnetic
resonance (MR) images of the cervical,
thoracic, and lumbar spine should be
obtained. Scoliosis secondary to a
syrinx, Chiari malformation, or osteoid
osteoma are examples of underlying
conditions that may cause scoliosis and
be mistaken for idiopathic scoliosis.
Also, scoliosis in a pre-adolescent,
scoliosis in the setting of thoracic
kyphosis greater than 40 to 50 degrees,
or scoliosis that has been rapidly
progressive should also be evaluated
with MRI.
• A characteristic of adolescent idiopathic
scoliosis is rotatory deformity that
presents as a hump or asymmetry in
the Adams forward-bending position.
If there is no significant rotatory
deformity on clinical examination and/
or on radiographs, a diagnosis other
than adolescent idiopathic scoliosis
should be suspected. Figure 22-1, A
shows scoliosis without rotation; Figure
22-1, B shows syrinx in this patient,
with no rotatory component to the
scoliosis.
• Consider the possibility of congenital
scoliosis. Radiographs should be
reviewed carefully to ensure that there
are no osseous abnormalities.
Indications
n
Thoracic scoliosis greater than or equal to 50 degrees
n
Thoracolumbar or lumbar scoliosis greater than or equal to 45 degrees
n
Slightly smaller curve magnitude than the above criteria in cases in which
there is significant decompensation or cosmetic deformity unacceptable to the
patient
Surgical Anatomy: Choosing Levels for Fusion
n
In general, the major curve, which is the largest measured curve, is always fused.
Figure 22-2 shows the Lenke classification.
I N D I CAT I O NS
C O N T RO V E R S IE S
• Anterior, rather than posterior, spinal
fusion may be performed if there
is a single major curve. This is
most commonly done in a single
thoracolumbar curve at this time.
A
FIGURE 22-1, A-B
Figures 22-1, 22-4 through 22-21, and 22-23 through 22-30 are reproduced with permission
from Children’s Orthopaedic Center–Children’s Hospital Los Angeles, Los Angeles, Calif.
B
Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis 209
Curve Type
Proximal Main Thoracolumbar/ Curve
Type Thoracic Thoracic Lumbar Type
1 Nonstructural Structural (major*) Nonstructural Main thoracic (MT)
2 Structural Structural (major*) Nonstructural Double thoracic (DT)
3 Nonstructural Structural (major*) Structural Double major (DM)
4 Structural Structural (major*) Structural Triple major (TM)
5 Nonstructural Nonstructural Structural (major*) Thoracolumbar/lumbar (TL/L)
6 Nonstructural Structural Structural (major*) Thoracolumbar/lumbar–
main thoracic (TL/L–MT)
*Major=largest Cobb measurement, always structural
airetirC larutcurtS
)sevruc ronim(
Proximal thoracic: Side-bending Cobb t25°
T2-T5 kyphosist+20°
Main thoracic: Side-bending Cobb t25°
T10-L2 kyphosis t+20°
Thoracolumbar/lumbar: Side-bending Cobbt25°
T10-L2 kyphosis t+20°
Modifiers
Minor=all other curves with structural criteria applied
Location of Apex
(SRS definition)
Curve Apex
Thoracic T2-T11-T12 disk
Thoracolumbar T12-L1
Lumbar T1-2 disk–L4
Lumbar
Spine
Modifier
A
B
C
CSVL to
Lumbar Apex
CSVL between pedices
CSVL touches apical body(ies)
CSVL completely medial
Curve type (1-6) + lumbar spine modifier (A, B, or C) + thoracic sagittal modifier (
A B C
Classification (e.g., 1B+): ________________
Thoracic Sagittal
Profile
T5–T12
– (hypo) <10°
N (normal) 10°-40°
+ (hyper) >40°
–
, N, or+)
FIGURE 22-2 CSVL, Center sacral vertical line; SRS, Scoliosis Research Society. (From Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic
scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 2001;83:1169-81.)
F U S I ON L E V E L PE A R L S
• The upper left thoracic curve should be
included if any of the following are
present:
• On physical examination
• The left shoulder is higher.
• The left ribs are higher at the base
of the neck.
• On a radiograph
• The left clavicle is significantly
higher.
• T1 on the left is tilted significantly
higher.
• The upper curve does not bend
out to less than 25 degrees.
• There is a very large main right
thoracic curve, approximately 70
degrees or greater, with substantial
correction expected.
• The lower instrumented vertebra on a
primary thoracic curve is most often a
vertebra touching the center sacral line
(Figure 22-3).
T4
T11
CSVL
FIGURE 22-3 CSVL, Center sacral vertical line; LIV, lower instrumented vertebrae;
UIV, upper instrumented vertebrae.
UIV
LIV
210 Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis
• The most common lower instrumented
vertebra for a selective thoracic fusion
with any curve with a Lenke B- or
C-type modifier is the vertebra most
closely bisected by the center sacral
line.
• For curves in which the lumbar apical
vertebral body is not completely
translated from midline (lumbar
modifiers A and B), selective thoracic
fusion is generally recommended. For
curves where the lumbar apical vertebra
is completely translated from the
midline (a lumbar C-modifier), in which
the center sacral line falls completely
medial to the most medial aspect of
the lumbar apical vertebrae, properly
selected curves may also be treated
with selective thoracic fusion. This
decision rests on many factors,
including the amount of rotation that
is present clinically and the relative
size and stiffness of the curve on
upright and bending films. This is a
controversial subject.
• The importance of careful evaluation
of the sagittal profile when choosing
fusion levels cannot be overstated.
From a sagittal perspective, if T2 to T5
is greater than or equal to 20 degrees
of kyphosis, or if T10 to L2 is greater
than 20 degrees of kyphosis, these
should be considered structural curves,
and they must be included in the
fusion.
A
FIGURE 22-4, A-B
Examination/Imaging
n
Physical examination includes a detailed neurologic examination, evaluation of
B
shoulder and iliac crest height, inspection of sagittal balance and notation of
any significant kyphosis or lordosis (Figure 22-4, A), and evaluation of rotational
F U S I ON L E V E L PI T F A L L S
• Not appreciating kyphosis in the sagittal
plane and ending instrumentation at
the apex of kyphosis is likely to lead to
junctional kyphosis and the need for
revision surgery.
• Never end the lower instrumented
vertebra at the apex of scoliosis. For
example, if an apex of the lumbar
curve is at L3, the lower instrumented
vertebra should never be L3, or there
will likely be significant
decompensation.
• Discipline yourself to count the
vertebrae and ribs for every scoliosis
case. An abnormal number of lumbar
or thoracic vertebrae could lead to the
inadvertent choice of the incorrect
fusion levels.
deformity in the Adams Forward Bending Test (Figure 22-4, B). Curves with
significant rotation in the Adams Forward Bending Test are more likely to be
structural than those curves without significant rotation.
n
Standard imaging includes posteroanterior (PA) (Figure 22-5, A) and lateral
standing (Figure 22-5, B) radiographs and supine bending radiographs to the
right and left (Figure 22-5, C and D). In large curves greater than about
90 degrees, supine traction films (Figure 22-6,
C
) are often more beneficial than
bending films (Figure 22-6, A and B). The authors routinely measure the Cobb
angles on the standing and bending films to aid in determining structural curves
and levels of fusion. It is crucial to determine the apex of kyphosis or any
abnormal areas of kyphosis to make certain that instrumentation does not end
in these areas.
Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis 211
A B
C
FIGURE 22-5, A-D
D
212 Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis
A B
C
FIGURE 22-6, A-C
Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis 213
Head
Transverse
P O S I TI O N I N G PE A R L S
• If the fusion is to extend to T2 or
higher, make certain the patient’s neck
is not extended, or the head will be in
the way of screw trajectory when
performing the instrumentation.
• The motto for preparation is “you can’t
get too high”; including the posterior
neck in the preparation will ensure
adequate access to the upper thoracic
spine.
• Early in positioning, place a strap
across the patient’s buttocks to prevent
caudad migration of the patient, which
will move the patient’s head into a bad
position and require repositioning
before starting (Figure 22-8).
• A Jackson top table easily allows for
halo femoral traction. For halo traction,
there is a small hole with a pulley
directly in line with the head. Traction
lines from the legs may be hung over
the end of the table (Figure 22-9).
P O S I TI O N I N G PI T FA L L S
• If the shoulders are abducted less than
90 degrees, the arms will be in the way
as the surgeon works on the upper
thoracic spine.
• If the shoulders or elbows are extended
upward toward the ceiling, imaging
of the upper thoracic spine will be
difficult. Slightly lowering the elbows
maximizes fluoroscopic lateral imaging
of the upper thoracic spine.
Positioning
n
The patient is positioned prone with the abdomen hanging free to prevent
venous congestion.
n
The patient may be positioned using a variety of methods, such as a Relton-Hall
frame, longitudinal rolls, transverse rolls, or a Jackson top table, which is the
authors’ preference. With a Jackson top table, the head is supported in a headholder, with a mirror underneath so that the anesthesiologist may visualize the
eyes and face. There is a transverse chest pad with disposable padding on top
of the table, which minimizes shear forces on the nipples. There are variablesized hip pads on which the anterior/superior iliac spines are centered. This
allows the abdomen and midline pelvis to hang free. The legs are placed in a
leg sling, often with pillows underneath and between them. The arms are placed
on arm boards. Traditionally, the shoulders should be abducted no more than
90 degrees to avoid stretch on the brachial plexus. As long as the arms are
being monitored, early notification of any significant neurologic or vascular
problems because of positioning should be apparent, and intraoperative adjustments can be made if necessary (Figure 22-7).
holder
FIGURE 22-7
chest pad
Hip pads
Leg sling with pillows
FIGURE 22-8
214 Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis
A N E S TH E S I A P EA R L S
• Communication with the anesthesia
team is crucial for a safe and efficient
operation.
• The authors’ preference is for the mean
arterial pressure to be 75 to 80 mm Hg
of mercury or higher during the
correction maneuver.
• Tranexamic acid is used to help reduce
blood loss. At the senior author’s (DLS’s)
institution, a 50 mg/kg loading dose
is given over 30 minutes (maximum
of 5 g) followed by 5 mg/kg/hr
maintenance dosing for idiopathic
scoliosis patients,
• Intrathecal opioids are drawn up by an
attending anesthesiologist and then
administered by the surgeon, either
before incision or early in the
dissection. At the senior author’s
institution, sufentanil 0.5 mc/kg
(maximum dose 30 mcg) and
Duramorph 5 mc/kg (maximum dose
250 mcg) are used.
FIGURE 22-9
P O RTA L S / E X P O S U R ES
P E A R LS
• Intraoperative imaging to confirm the
proximal and distal fusion levels should
be done early in the dissection to
confirm the correct location.
• Well-placed self-retainers with very
significant tension will aid in pulling
tissue off the bone. The authors’
preference is generally a cerebellar
distractor at the very top and bottom
of the wound, with one or two longer
straight retractors toward the middle of
the wound (Figure 22-10).
• Use of a fibrin sealant sprayed on the
soft tissues may aid in minimizing
bleeding.
• Bone wax placed directly on any
bleeding bony surfaces will help to
minimize blood loss.
• Make certain the lateral and inferior
aspects of the facet joints are carefully
dissected free of soft tissue. If this
is done at the time of the initial
dissection, it will save time during the
facetectomies. Otherwise, during the
facetectomies, there will be bleeding
from soft tissue attachments.
• The interspinous ligament and facet
joint capsules above and below the
extent of the intended fusion must
be kept intact, or there will be an
increased risk of junctional kyphosis.
FIGURE 22-10
Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis 215
Portals/Exposures
n
A slightly curvilinear incision is made so that, when the spine is straightened,
the incision will straighten as well. The curve of the incision should be larger
for larger scoliotic curves and thinner children and, conversely, straighter for
smaller scoliotic curves and more obese patients.
n
After the initial incision, Bovie cautery is used for dissection. Care should be
taken to dissect exactly in the midline, which is an avascular plane. The spinous
processes may be palpated with the fingers or a Cobb elevator. The cartilaginous
cap over the spinous process may be split in half. The muscles are removed from
the bone with Bovie cautery, while applying tension to the soft tissues with a
Cobb elevator. Note that the Cobb elevator does not scrape the muscles from
the bone, but rather applies tension, often quite significant tension, to enable
this separation from muscle and bone to be done with cautery.
n
Dissection should be done subperiosteally to fully expose the lamina and
the facet joints, and to proceed to the tips of the transverse processes
bilaterally.
Procedure
S T E P 1 P EA R L S
• A complete facetectomy, leaving the
superior facet joint intact, is crucial in
order to visualize the starting point for
the pedicle screw, to mobilize the spine,
and to maximize fusion (Figures 22-12
and 22-13).
FIGURE 22-11
Step 1: Facetectomies
n
Thoracic spine: Using a
osteotome, make a square cut to remove the inferior facet joint. This should
expose the superior facet joint in its entirety (Figure 22-11).
n
Lumbar spine: A
remove the inferior facet in the lumbar spine. An alternative method is to
remove it with a rongeur.
1
-inch osteotome or a specially designed square-cut
2
1
-inch osteotome, usually with a single blow, is used to
2
FIGURE 22-12
216 Procedure 22 | Posterior Thoracolumbar Fusion Techniques for Adolescent Idiopathic Scoliosis
S T E P 1 P IT FA L L S
• Performing the facetectomy with a
power burr may lead to bleeding
and disruption of the superior facet
cartilage, making visualization more
difficult.
• An incomplete facetectomy may lead to
a misjudgment of the starting point of
the pedicle screw.
S T E P 2 P EA R L S
• Resection of the interspinous ligament
and ligamentum flavum is often carried
out with a single grasp, with a large
rongeur in experienced hands.
• Full removal of all posterior soft tissue
structures, including the joint capsule,
interspinous ligament, and ligamentum
flavum is essential to produce
physiologic thoracic kyphosis if the
spine is hypokyphotic preoperatively.
• It is not necessary to remove the
ligamentum flavum near the proximal
or distal end vertebra if significant
correction is not expected from these
levels.
Step 2: Release of the Spine
n
The authors typically release the inferior half of the spinous process, the inter-
spinous ligament, and the ligamentum flavum. This may be done with a spinous
process cutter, a rongeur for the interspinous ligament, and a Kerrison rongeur
or punch for the ligamentum flavum.
Step 3: Pedicle Screw Placement
n
The starting point for the thoracic pedicle screw from a mediolateral direction
FIGURE 22-13
is just lateral to the midpoint of the superior facet. In a cephalad-caudad posi-
S T E P 2 P IT FA L L S
• All members of the surgical team must
take note that, from this point forward
in the procedure, the spinal canal is
open, and care must be taken to avoid
inadvertent entrance into the canal,
especially by less-experienced surgical
assistants.
tion at T1, T2, and T12 (upper and lower thoracic spine), the starting point is
the midline of the transverse process. Where these two lines intersect is the
starting point for the pedicle screw. At T7, T8, and T9 (mid-thoracic spine), the
very cephalad edge of the transverse process provides the cephalad-to-caudad
starting point. The saying “7, 8, 9 sure is fine” may help one remember this.
n
The starting point in the lumbar spine is the intersection of the pars interarticu-
laris and the midpoint of the transverse process.
n
There are many different methods of starting pedicle screws, including use of a
pedicle probe, a curette, or the authors’ preference of power assistance with a
drill. (The authors routinely have three drills on a scrub table.)
n
S T E P 3 B PE A R L S
• To differentiate between cortical bone
and the soft cancellous channel, a
slow-moving drill bit provides more
tactile feedback than does a stiff
pedicle probe.
Pedicle screws can be placed under fluoroscopic/image guidance or using a
freehand technique.
•
Step 3A:
A Midas Rex M8 burr (Medtronic, Minneapolis, Minn.) or equivalent
is used to make a very small decortication at the pedicle screw starting point,
just deep enough to go to the cortex. Often, the cancellous bone of the
pedicle can be visualized at this point.