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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6030_Библиотеки_им_академика_М_И_Перельмана.pdf
A B
Figure 38–1
Postoperative posteroanterior (PA) radio-
graph 15 months after posterior spinal fusion
(PSF) with instrumentation demonstrating
many features of the crankshaft phenomenon.
Figure 38–2
A skeletally immature girl with severe scoliosis and a history of congenital heart disease.
(A) Preoperative PA radiograph. (B) Postoperative PA radiograph taken 2 years after anterior spinal fusion (ASF)/PSF, with instrumentation done at the same setting.
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180
Figure 38–3
Postoperative PA radiograph of a skeletally immature boy after ASF with instrumentation.
SECTION II THE THORACIC SPINE
Eurostile
A B
Figure 38–4
(A) Intraoperative view of completed discectomies and preserved segmental vessels using open thoracotomy. (B) Intraoperative view of disc spaces packed with morselized
autogenous rib graft.
A
Figure 38–5
(A) Intraoperative view of discectomy performed utilizing the thoracoscopic approach. (B) Intraoperative view through the thoracoscope of disc spaces packed with allo-
graft.
B
Eurostile
38 PREVENTION AND TREATMENT OF THE CRANKSHAFT PHENOMENON
181
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39
Thoracic Scoliosis
Vertebral Resection
Kirkham B. Wood
Goal of Surgical Treatment
The goal is to reestablish spinal balance in the sagittal, coronal, and axial
planes. Because the risk of neurologic injury is so strong when attempting
to correct fixed, rigid, severe, spinal deformities, the resection of one or
more apical vertebral bodies allows for the “shortening” of the spinal
column and less risk of neurologic trauma.
Diagnosis
Thoracic scoliosis is a three-dimensional rotational deformity of the spine
whose apex lies between T2 and T12. This chapter deals with a select subset of thoracic scoliosis: the spine that cannot be brought into balance
through either the traditional posterior approach or a combined anterior/
posterior operation with or without osteotomies. This diagnosis is made by
history (e.g., multiple previous failed operations, untreated congenital deformity), and plain radiographs including bending films to assess flexi-
bility as well as compensation. The spine is further stiffened by the ribs,
thorax, and sternum.
Indications for Surgery
A fixed and rigid thoracic scoliosis in which, based on the physical examination, history, and radiology including bending x-rays, it is felt that even a
combined anterior/posterior approach stands a high chance of failing to
adequately balance the spine.
1. Significant cosmetic deformity
2. 쏜 6-cm coronal plane imbalance that cannot be centered on side bend-
ing
3. Fixed upper thoracic and pelvic obliquity
4. Fixed asymmetric length between the concave and convex sides of the
spine
5. Severe rigid thoracic scoliosis that threatens to worsen
Contraindications for Surgery
1. A flexible thoracolumbar spine that corrects on side-bending into a
more physiologic range
2. Previous anterior thoracic exposure (relative)
3. Active spinal infection
Advantages
1. Ability to balance (in three planes) a rigidly fixed thoracic scoliosis de-
formity typically resistant to correction from either a posterior alone or
a posterior/anterior approach.
2. Improved cosmesis.
3. Shortening the spine (versus lengthening the spine as in a closing
wedge osteotomy posteriorly) lessens the risk of neurologic injury.
4. Thoracoplasty can be combined for those with residual axial plane de-
formity and to increase flexibility, and it provides abundant autogenous bone graft.
Disadvantages
1. High complication rate
2. Minor complications (e.g., dural tears) common
3. High blood loss
4. Operating room time and surgeon fatigue
5. Morbidity associated with the anterior exposure
6. Risk of pulmonary and neurologic injury
Procedure
Resection Levels
The number of vertebrae to be removed depends on the severity of the
curve and the degree of coronal imbalance. Typically it runs from one to
three vertebrae resected at the apex of the deformity. Beyond the resected
segment, discectomies and/or osteotomies are performed to aid in the cor-
rection.
Incision
Anteriorly, a curvilinear lateral incision is made over the area of resection
on the convex side of the deformity, as in either a standard thoracotomy or
a thoracoabdominal approach. A common approach is to make the incision
over the uppermost rib to be included in the fusion. Anteriorly, a standard
midline incision is made from two levels above the uppermost vertebrae to
be included to one below the most caudad vertebrae.
Exposure Secrets
1. A thoracotomy is performed at one segment above the most cephalad
level to receive attention.
2. The rib itself can be removed subperiosteally and used for bone graft,
or the thoracotomy can be between two ribs. Some believe that this
may lead to a more cosmetic result.
3. For longer segments, a second, more caudal thoracotomy can be performed to aid in the exposure of more distal segments. In this case, the
original skin incision should be based between the two thoracotomies
and subcutaneous flaps elevated to gain access to the ribs to be removed.
4. If desired, once the vertebrae for resection have been identified and exposed, and the segmental vessels ligated, an osteoperiosteal flap can be
created (Fig. 39–1). This technique can be used to contain the bone
graft material at the close of the anterior procedure.
5. After the vertebrae and pedicles have been removed completely back
to the exposed dura, Gelfoam or the like should be placed to protect the
neurologic elements against bone graft.
Posterior Correction
1. The posterior stage may follow the anterior surgery under the same anesthetic if the patient is medically stable, the length of the procedure is
not expected to extend beyond 10 to 12 hours, the blood loss is not excessive, and fatigue of the surgical team is not a factor.
2. The posterior exposure is standard over the length of the spine to be instrumented.
3. Where the vertebrae were resected anteriorly, the posterior remainder
of the vertebrae are removed, including any residual pedicles to the exposed dura, which is also protected with Gelfoam as in the anterior
stage.
4. In cases of dramatic rotational deformity, or if no autograft remains at
the ilia, convex side thoracoplasty can be performed, which may also
aid in deformity correction if the ribs can be disarticulated from the
vertebrae (Fig. 39–2).
5. Instrumentation is performed segmentally, taking care to avoid distraction of the anterior construct. Placing the convex rods first tends to
help guard against overdistraction more so than concave rods.
Grafting
Anteriorly, after the vertebrae have been resected, the morselized bone is
returned with autograft rib, if taken, into the bed created. If raised, the
osteoperiosteal flap can then be closed back down around the graft material (Fig. 39–3). Any bone harvested either from the iliac crest or from a
thoracoplasty is placed over the posterolateral spine over the entire levels
of instrumentation.
Pitfalls and Complications
1. After the posterior elements have been removed, some spontaneous
shortening will be seen. Because the dura will tend to buckle somewhat, it is important to undercut the margins of the resected posterior
segment to protect the underlying neurologic elements.
2. Correction of the coronal plane deformity should be that necessary to
achieve and maintain three-dimensional balance. Overcorrection can
lead to potential problems with decompensation in either the coronal
or sagittal planes.
3. Because many patients will have had multiple prior procedures and
resultant osteopenia, overcorrection may place undue strain on the instrumentation, risking perioperative metal-bone failure.
4. Because many individuals will have had multiple prior procedures, removing bone back to the dura may be complicated by adhesions. Dural
tears may well be the most frequent complication encountered.
5. Overcorrection with distraction can lead to the superior mesenteric
artery syndrome.
6. Radiographs should be taken more than once during the posterior instrumentation to ensure the maintenance of coronal balance.
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182
SECTION II THE THORACIC SPINE
Eurostile
T4
Rib 6
5
7
8
9
Skin
incision
A.
L.
L.
Disc
Rib
A
resected
for graft
Pedicle
Ao
Axial section
Resected
rib
Rib remnant
Dura
PLL
Area of
bone removal
(anterior approach)
Periosteum
ALL
Osteoperiosteal flap
T7
Figure 39–1
(A,B) An osteoperiosteal flap can be created.
Anterior
longitudinal
ligament
B
Eurostile
39 THORACIC SCOLIOSIS: VERTEBRAL RESECTION
183
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Bone graft
and chips
Osteoperiosteal
flap
C7
T1
Skin
incision
Rib
T5
T12
Figure 39–2
Incision and convex-side thoracoplasty of T5.
Rib graft (optional)
Osteoperiosteal
flap
Bone
chips
B
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184
Figure 39–3
(A) Morselized cancellous bone graft can be returned to the vertebrectomy site
and the osteoperiosteal flap closed. (B) Axial view.
SECTION II THE THORACIC SPINE
Eurostile
A
Postoperative Care
A rigid thoracolumbosacral orthosis is worn until a solid arthrodesis is
achieved. If the lumbosacral junction has been included, a thigh extension
should be added to the orthosis. (We attempt to avoid fusing to the lum-
bosacral junction, if at all possible. Those with severe pelvic obliquity,
those with associated degeneration of the lumbosacral disc, and those with
sagittal flatback-type deformity, however, are typically fused down to the
pelvis or sacrum.)
Suggested Readings
Bradford DS, Glazer PA. Vertebral column resections for severe deformi-
ties. In: Bridwell KH, DeWald RL, eds. The Textbook of Spinal Surgery.
2nd ed. Philadelphia: Lippincott-Raven; 1997:2227–2241.
Bradford DS, Tribus CB. Vertebral column resection for the treatment of
rigid coronal decompensation. Spine 1997;22:1590–1599.
Tokunaga M, Shohei M, Kitahara H, Isobe K, Nakata Y, Moriya H. Vertebral
decancellation for severe scoliosis. Spine 2000;25:469–474.
Eurostile
39 THORACIC SCOLIOSIS: VERTEBRAL RESECTION
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40
Technique of Sublaminar Wire Passage
Vincent J. Devlin and Marc A. Asher
Goal of Surgical Treatment
To achieve secure segmental fixation of the posterior spinal elements.
Indications
1. Scoliosis
2. Kyphosis
3. Hyperlordosis
4. Fractures
5. To provide supplementary fixation for adjacent hook or screw fixation
sites (Figs. 40−1 and 40−2)
Contraindications
1. Deficient lamina (e.g., postlaminectomy deformity)
2. Conditions where the epidural space is compromised (e.g., tumor) or
where the spinal cord is enlarged (e.g., syrinx)
Advantages
1. Sublaminar wires provide an inexpensive, versatile, and rapid tech-
nique for fixation of multiple spinal segments.
2. Sublaminar wires are excellent implants for translating vertebral seg-
ments.
3. Sublaminar wires provide a variable position connection that facili-
tates rod-anchor linkage in severe spinal deformities.
Disadvantages
1. Sublaminar wires do not provide axial or rotational stability to the in-
strumented spinal segments.
2. Sublaminar wires may directly traumatize the spinal cord and cause
neurologic injury.
Procedure
Laminotomy
The goal of this step is to provide a clear view of the entrance and exit sites
for wire passage. Interspinous ligaments and capsular soft tissue are removed to permit visualization of the interlaminar space at each level
where wires will be placed. In the thoracic region, a small amount of the
spinous process and the inferior lamina edge overlying the interlaminar
space are removed to facilitate exposure because these caudal structures
overlie the interlaminar space. This step is not generally required in the
lumbar region. A double-action rongeur is then used to remove ligamentum flavum from the midline of the interlaminar space, thereby exposing
the epidural space (Fig. 40–3A). A Penfield No. 4 dissector is used to gently
develop a working plane and separate the epidural fat and the internal
venous plexus from the underside of the ligamentum flavum (Fig. 40–3B).
Epidural bleeding can be minimized by attention to these steps. A 45degree Kerrison rongeur is then used to remove residual ligamentum
flavum from the interspace along with a small portion of the inferior laminar margin to achieve adequate visualization of the epidural space (Fig. 40–
3C). The majority of the spinous process is saved, as this provides a bed for
soft tissue reattachment and a site for fusion mass to accumulate. This
sequence of preparation is repeated at every level where wires will be
placed. Gelfoam soaked in thrombin along with cottonoids, cotton oxacil,
or bipolar electrocautery may be used to control epidural bleeding encountered at this stage.
Wire Preparation
Either single- or double-strand wires may be used. A gentle C-shaped bend
is placed at the end of the wire. Bending the tip of the wire over the handle
of a Cobb elevator is a useful technique for creating this primary bend. The
bend of the wire tip should not be greater the 45 degrees. The diameter of
the bend should be slightly larger than the lamina around which the wire is
to be passed, to minimize wire intrusion into the spinal canal. A secondary
bend may be placed more proximally to facilitate wire passage.
Wire Passage
The tip of the wire is introduced by hand into the epidural space in the
midline at the inferior laminar margin. The wire is passed in a caudad to
cranial direction, keeping the tip of the wire in contact with the undersurface of the lamina (Fig. 40–3D). The tactile feedback provided by wirelaminar contact is critical to ensuring a safe wire trajectory. After the wire
has been safely introduced and advanced into the epidural space, the tip of
the wire is rolled around the lamina in a single smooth motion that results
in visualization of the wire tip at the interlaminar space above. The tip of
the wire is grasped with a needle holder or wire puller and guided gently
around the lamina (Fig. 40-3E). During this pull-through phase, upward
tension must be maintained on both ends of the wire to prevent the arc of
the wire from impinging on the dura.
Wire Stabilization
The wire is stabilized to prevent accidental displacement toward the spinal canal by bending the wire down against the lamina (Fig. 40–3F). The
orientation of the bend should permit the superior half of the wire to be
positioned medially and the inferior half of the wire to be positioned laterally in relation to the rod.
Wire Tightening
The sequence of wire tightening depends on the instrumentation technique utilized and the nature of the spinal deformity undergoing treatment. After placement of the longitudinal member, the tips of the wires to
be tightened are crossed in a clockwise fashion. A jet-twister is used to
grasp the junction where the wires cross, and upward tension is used to
tighten the wire. This is done sequentially over all of the spinal segments
where wires have been placed. The wires are revisited and retightened as
needed. It is critical to maintain constant upward traction on the wires
during the tightening process to prevent inadvertent impingement of wires
upon the contents of the spinal canal.
Wire Finishing
After final wire tightening is completed, the tips of the wires are cut to a 1or 2-cm length and bent toward the midline to decrease the prominence of
the wires and direct the wires away from the area of intended arthrodesis.
Technical Tips
Timing of wire placement during a procedure is critical. It is preferable to
defer wire placement until immediately prior to correction of a spinal deformity. This permits complete exposure of the spine, facet joint preparation, placement of hooks and screws, and bone graft harvest to be carried
out without the risk of inadvertent displacement of wires toward the spinal
canal. This sequence also results in decreased blood loss, because bleeding
tends to increase following the multiple laminotomies required for wire
placement.
Lateral sub-pars interarticularis placement of wires is possible, and
provides a greater mechanical advantage for vertebral derotation as well as
greater posterior pullout stability. To obtain sub-pars placement, more of
the inferior facet and some of the superior laminar edge must be removed.
Sub-pars placement should be undertaken cautiously, as the risk of nerve
root or posterior primary ramus injury may be increased with wires placed
in this position (Fig. 40–3G).
Pitfalls
If any resistance to passage of a sublaminar wire is encountered, it is best to
remove the wire and reattempt wire placement, ensuring that the wire passage is initiated from a midline position.
Complications
Neurologic injury: Sublaminar wires may directly traumatize the spinal
cord and result in immediate neurologic injury. Delayed neurologic complications from sublaminar wires may result from slow epidural bleeding,
cord edema, or irritation caused by wire position. The best solution for this
complication is prevention.
Wire breakage: Broken wires are occasionally noted following surgery.
Improper surgical technique may predispose to this complication. Overtightening of wires may weaken the wire twist and predispose to subsequent failure. Failure to adequately contour spinal rods so that they lie
firmly on the lamina and against the base of the spinous processes may
lead to weakening of wires as the surgeon will tend to overtighten the wires
to approximate the rod to contact the spine. It is better to correct the deformity by approximating the rod to the level of the spine with a rod holder
prior to initiating wire tightening. An additional maneuver that is helpful
in correction of scoliosis is to utilize rod benders to temporarily bow the
concave rod anteriorly to relieve stress on the concave wires as they are
tightened.
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186
SECTION II THE THORACIC SPINE
Eurostile
A, B
Figure 40–1
Preoperative standing posteroanterior (PA) (A) and lateral (B) views
of the spine.
A, B
Eurostile
Figure 40–2
Postoperative standing PA (A) and lateral (B) views of the spine.
40 TECHNIQUE OF SUBLAMINAR WIRE PASSAGE
187
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Partial resection of
Decorticate
facets
Ligamentum
flavum
spinous process
in thoracic
spine
A
Figure 40–3
(A−G) Intraoperative drawings demonstrate the steps involved in sublaminar wire passage.
B
Ligamentum
flavum
Dura
C
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188
SECTION II THE THORACIC SPINE
Eurostile
Wire
passage
D
Wire pulled
through from
caudal to cranial
under tension
Needle holder
E F
Eurostile
40 TECHNIQUE OF SUBLAMINAR WIRE PASSAGE
189
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