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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6030_Библиотеки_им_академика_М_И_Перельмана.pdf
Figure 24–4
This schematic is a synopsis of all necessary criteria for curve classification by
this new method and highlights the six curve types, lumbar spine modifiers,
and sagittal modifiers. (From Lenke LG, et al. Adolescent idiopathic scoliosis.
J Bone Joint Surg Am 2001;83:1169, with permission.)
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Figure 24–5
This schematic depicts all potential curve types as well as lumbar modifiers possible for this new
classification. In addition, potential sagittal structural criteria that determine the specific curve
type are listed as well. (From Lenke LG, et al. Adolescent idiopathic scoliosis. J Bone Joint Surg Am
2001;83:1169, with permission.)
SECTION II THE THORACIC SPINE
Eurostile
thoracic sagittal profile to optimize sagittal alignment during concomitant
scoliosis correction. For these reasons, we have devised a simple thoracic
sagittal modifier to complement the six curve types and three lumbar spine
modifiers presented.
The sagittal thoracic modifier is based on the upright lateral radiograph
and measured from the superior end plate of T5 to the inferior end plate of
T12 (T5-T12). When this measurement is less than +10 degrees, the sagittal
modifier is designated as a “−” or hypokyphosis; when the measurement is
between +10 degrees and +40 degrees, it is designated as “N” or normal kyphosis; and for measurements greater than +40 degrees, the designation is
“+” or hyperkyphosis.
Complete Curve Classification
Complete curve classification thus combines the specific curve types 1 to 6
along with the lumbar spine modifier (A, B, C) and the sagittal thoracic
modifier (−, N, or +) to form the specific curve classification (for example,
1A−, 1AN, 1A+, 1B− . . ., 6CN, 6C+). Although this produces a total of 42
possible curve classifications, if one follows the rule of assigning the appropriate curve types 1 to 6 and adds the appropriate lumbar spine and
sagittal thoracic modifiers separately, then specific curve classification follows logically and easily. A one-page information sheet has been
developed to provide all the necessary requirements for proper curve
classification (Fig. 24–4), and a one-page schematic highlights the coronal
differences between the six curve types and the three lumbar modifiers
(Fig. 24–5).
Implications of Classification on Operative Treatment
1. Curve type 1 (main thoracic, MT): the MT curve will be fused.
2. Curve type 2 (double thoracic, DT): both the PT and MT curves will be
fused.
3. Curve type 3 (double major, DM): the MT and TL/L curves will be
fused.
4. Curvetype 4 (triple major, TM): all three curves, PT, MT, and TL/L, will
be fused
5. Curve type 5 (thoracolumbar/lumbar, TL/L): only the TL/L curve will
be fused.
6. Curve type 6 (thoracolumbar/lumbar-main thoracic, TL/L-MT) both
the MT and TL/L curves will be fused (Table 24–3).
For lumbar modifiers A and B, it is anticipated that the lumbar spine
will not require fusion. One exception to this is if a thoracolumbar
junctional kyphosis exists in the sagittal plane (T10-L2 쏜 +20 degrees), re-
quiring inclusion of this region in the instrumentation and fusion of the
curve below.
In main thoracic curves that are quite large (쏜 +75 degrees), often the
thoracolumbar/lumbar coronal plane is structural in and of itself because
of the large compensatory thoracolumbar/lumbar Cobb measurement (e.g.,
curve types 3A and 3B, as well as 4A and 4B).
Lumbar modifier C may or may not require the lumbar curve to be in-
cluded in the instrumentation and fusion of a main thoracic curve. For
those with a MT 1C (main thoracic) curve, the goal is to perform a selective
thoracic fusion to leave the lumbar spine mobile to accommodate and
balance if possible. This is in distinction to a 3C (true double major) curve
pattern where invariably the lumbar spine will be included in the instrumentation and fusion of the main thoracic region. Occasionally, there is a
fine line between the 1C and 3C curve patterns, and ratio criteria of
thoracic to lumbar (T:L) Cobb measurements, apical translations, and api-
cal rotations that will be required in addition to the structural criteria as
listed for this classification system.
Lastly, it is important to evaluate the clinical appearance of the patient
when separating out a true (3C) versus false (1C) double major curve pattern. If there is a marked discrepancy between the thoracic (greater) and
lumbar (lesser) cosmetic appearance, often a selective thoracic fusion can
be successfully performed. When the thoracic and lumbar cosmetic ap-
pearance is equal, this usually indicates a true double major curve pattern
that will require both curves to be instrumented and fused. For type 5 and 6
curves of the C modifier, the thoracolumbar/lumbar curve will always be
included in the instrumentation and fusion. Most type 6 (TL/L−MT)
curves will also require the main thoracic curve to be fused as well.
The treatment implications of the sagittal thoracic modifier are also
quite important. For a hypokyphotic sagittal modifier (−), the goal of instrumentation and fusion of the thoracic region is to improve thoracic kyphosis with either posterior or, more recently, anterior instrumentation
techniques. For a normal (N) sagittal modifier, the goal is to maintain normalized thoracic sagittal alignment. For a hyperkyphotic (+) sagittal modifier, the goal is to reduce thoracic kyphosis into the normal range. This will
usually require instrumentation and fusion from a posterior route with
convex compression forces applied prior to any concave distraction forces.
Thus, all components of this triad classification system produce treatment implications of regions of the spine to be fused, as well as specific
techniques to optimize coronal and sagittal curve correction and balance.
Conclusions
This new classification system of AIS appears to meet most of its goals: it is
comprehensive for all AIS curve types; it is two dimensional with increased emphasis placed on the sagittal plane; specific curve types are separated by strict objective radiographic criteria; and it is treatment-based.
Inter- and intraobserver reliability and usefulness for practicing scoliosis
surgeons is being prospectively evaluated. It is the beginning of a comprehensive algorithmic approach to AIS that will identify the curve types 1 to
6, and both the lumbar curve modifier (A, B, C) and a sagittal thoracic
modifier (−, N, or +) to produce a specific curve classification (e.g., 1A−).
Ideally in the future, standardization of curve classification by this method
will allow a critical comparison of various surgical treatments of very similar curve patterns.
Suggested Readings
Bernhardt M, Bridwell KH. Segmental analysis of the sagittal plane align-
ment of the normal thoracic and lumbar spine and thoracolumbar
junction. Spine 1989;14:717–721.
Betz RR, Harms J, Clements DH, Lenke LG, Lowe TG, Shufflebarger H.
Comparison of anterior versus posterior instrumentation for correction
of adolescent thoracic idiopathic scoliosis. Spine 1999;24:225–239.
Bridwell KH, Betz RR, Capelli AM, Huss G, Harvy C. Sagittal plane analy-
sis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation. Spine 1990;15:921–926.
Bridwell KH, McAllister JW, Betz RR, Huss G, Clancy M, Schoenecker PL.
Coronal decompensation produced by Cotrel-Dubousset “derotation”
maneuver for idiopathic right thoracic scoliosis. Spine 1991;16:769–
777.
Kalen V, Conklin M. The behavior of the unfused lumbar spine following
selective thoracic fusion for idiopathic scoliosis. Spine 1990;15:271–
274.
King HA, Moe JH, Bradford DS, Winter RB. The selection of fusion levels in
thoracic idiopathic scoliosis. J Bone Joint Surg Am 1983;65:1302–
1313.
Lee CK, Denis F, Winter R, Lonstein JE. Analysis of the upper thoracic
curve in surgically treated idiopathic scoliosis: a new concept of the
double thoracic curve pattern. Spine 1993;18:1599–1608.
Lenke LG, Betz RR, Bridwell KH, et al. Intraobserver and interobserver re-
liability of the classification of thoracic adolescent idiopathic scoliosis. J Bone Joint Surg Am 1998;80:1097–1106.
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;83:1169−1181.
Lenke LG, Betz RR, Harms J, Clements DH, Lowe TG, Bridwell KH. Spon-
taneous lumbar curve coronal correction after selective anterior or
posterior thoracic fusion in adolescent idiopathic scoliosis. Spine
1999;24:1663–1671.
Lenke LG, Bridwell KH, Baldus C, Blanke K. Preventing decompensation
in King II curves treated with Cotrel-Dubousset instrumentation: strict
guidelines for selective thoracic fusion. Spine 1992;17:274–281.
Lenke LG, Bridwell KH, Baldus C, Blanke K, Schoenecker PL. Cotrel-
Dubousset instrumentation for adolescent idiopathic scoliosis. J Bone
Joint Surg Am 1992;74:1056–1067.
Richards BS. Lumbar curve response in type II idiopathic scoliosis after
posterior instrumentation of the thoracic curve. Spine 1992;17:S282−
S286.
Roye Jr DP, Farcy JP, Rickert JB, Godfried D. Results of spinal instrumenta-
tion of adolescent idiopathic scoliosis by King type. Spine
1992;17:S270−S273.
Shufflebarger HL, Clark CE. Fusion levels and hook patterns in thoracic
scoliosis with Cotrel-Dubousset instrumentation. Spine 1990;15:916–
920.
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24 ADOLESCENT IDIOPATHIC SCOLIOSIS
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25
Anterior Correction and Instrumentation for Thoracic Scoliosis
Thomas R. Haher and Andrew A. Merola
Goals of Surgical Treatment
To balance, correct, and stabilize the curvature.
Diagnosis
Thoracic scoliosis is defined as an appreciable lateral deviation of the
spine in the frontal plane (rotation about the X-axis). The apex of the curve
must lie within the T2 to T11-T12 disc. The diagnosis is made by physical
examination (rib, shoulder, and/or waist asymmetry) an as well as
measurements of a standing anteroposterior (AP) and lateral x-ray of the
spine taken on a 36-inch cassette (Fig. 25–1).
Indications for Surgery
1. Thoracic curves in children with growth potential remaining
2. Significant thoracic cosmetic deformities
3. Severe thoracic curves in the mature patient
Contraindications
1. Thoracic hyperkyphosis
2. Structural proximal thoracic and lumbar curves
Advantages of Anterior Approach for Thoracic Curves
1. Shorter fusion
2. Improved correction and cosmesis
3. Reduction in blood loss
Disadvantages
1. Hyperkyphosis
2. Shoulder asymmetry with a proximal thoracic curve
3. Waist asymmetry with a structural lumbar curve
4. The associated morbidity of a thoracotomy
Procedure
Fusion Levels
With anterior surgery the vertebra most tilted into the curve on the standing film should be included in the instrumentation, encompassing the entire vertebra included in the Cobb angle (Fig. 25–2), usually from neutral to
neutral vertebra rather than stable to stable vertebra as in a posterior fusion.
Incision Options
Option 1: The incision is made from the posterior angle of the rib two
levels above the apex of the curve. The incision is carried along the body of
the rib to the costal cartilage and carried down through the muscular layers
of the thoracic wall. The periosteum of the rib is incised along the direction
of the incision to allow a subperiosteal stripping and removal of the rib.
The rib is divided at the posterior angle and at the junction of its costal cartilage (Fig. 25–3).
Option 2: The incision is made as explained above. The incision is car-
ried between the ribs through the muscle wall. The rib is not harvested for
graft. Some surgeons believe that this technique permits a more cosmetic
chest closure.
Option 3: An incision may be made at the level of the ultimate vertebra
in the curve. It allows excellent exposure of the proximal portion of the
curve. To achieve exposure of the remaining vertebrae in the curve,
osteotomies are performed of all ribs below the incision.
Option 4: The incision is made from the posterior angle of the rib two
levels above the apex of the curve. The chest is entered through two subcutaneous thoracotomies, separated by four ribs. This option allows excellent
exposure for large, rigid curves (Fig. 25–4).
Exposure Secrets
1. If exposure is limited secondary to a “tight chest wall,” small osteoto-
mies of the adjacent ribs may be done.
2. Segmental vessels: The segmental vessels are identified and isolated
by a Mixter or Addison. If the vessels are to be spared, vessel loops are
placed in the teeth of the instrument and passed beneath the vessels.
The vessels may then be mobilized and retracted without injury to
allow placement of the screws (Fig. 25–5).
3. Preparation of the disc space: The rib heads are identified and removed
utilizing an osteotome or rongeur. This exposes the posterolateral
corner of the disc. The sympathetic trunk is bluntly dissected from
each rib head. Electrocautery should not be used in this region (Fig. 25–
6).
4. Thoracoplasty: The parietal pleura is incised over the angle of each
apical rib and a section of rib angle is removed.
5. Placement of the vertebral screws: The screws are inserted into the
vertebral body across the largest diameter. The screws may be directed
slightly posterior to anterior to decrease the chance of neurologic injury. In severe or rigid curves the top and bottom screw may be left
proud with up to two threads exposed. This technique simplifies the
rod-screw insertion without compromising the pullout strength of the
screw. Screw placement in the superior and inferior vertebral bodies is
difficult. The technique of thoracoscopic stab wounds may be utilized
to provide adequate access. A small (쏝3 cm) incision is made between
the ribs to provide access for instrumentation and screw placement at
these levels (Fig. 25–7).
Insertion of the Rod
1. 4-mm rod: If a small diameter rod (resilient) is used, pre-bending of the
rod is not necessary and the rod rotation maneuver is not needed.
Four-millimeter threaded and solid rods are available. The rod is compressed over the convexity of the curve in a harmonious fashion.
2. 5-mm rod: A large-diameter rod (decreased resiliency) may be used;
however, the rod must be pre-bent, and a rod rotation maneuver is performed. Proximal or distal screw pullout may result with the loss of
fixation at these regions. All compression is performed toward the
apex of the curve (Fig. 25–8).
Pitfalls
1. Beware of, and identify, the presence of any structural curves such as a
rigid upper thoracic curve. Failure to recognize secondary structural
curves will result in neck and shoulder asymmetry or waist asymmetry. Posterior fusion and instrumentation should be considered if
structural curves are present (Lenke types 2 and 4).
2. Proximal screw pullout may occur with the use of a 5-mm rod with or
without the rod rotation maneuver.
Complications of Instrumentation
1. Loss of spinal balance secondary to the presence of an unrecognized
secondary structural curve: Preoperative bending films must be analyzed and the criteria for a structural curve must be applied to avoid
this complication.
2. Instrumentation failure at rod-anchor junction: The inner and outer
screws and nuts must be placed properly without cross-threading. If
side-loading screws are used, they must be placed at the top and bottom of the construct with the side opening opposite to the location of
the rod prior to insertion.
3. Instrumentation failure at the screw-bone interface: This is a common
complication with proximal screw insertion at or above T4. The vertebral body is small and the forces applied to the 5- or 6-mm screw often
result in fractures of the vertebra. If the rod is pre-bent and rod rotation
is performed, the greatest forces are realized at the top screw where the
vertebral body size is the smallest. Screw pullout often results with the
loss of that level in the construct.
Postoperative Care
1. Chest x-rays every day until the chest tube is removed.
2. The chest tube may be removed when the drainage is less than 100
cc/24 hours.
3. The patient may be out of bed the first postoperative day, and ambulating is encouraged.
4. Postoperative TLSO is used at the discretion of the surgeon.
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SECTION II THE THORACIC SPINE
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Figure 25–1
A
Preoperative standing anteroposterior (AP) (A) and lateral (B) x-rays of the spine.
B
The curve is classified as a Lenke 1BN.
Figure 25–2
(A,B) Postoperative films with instrumentation of all levels within the Cobb angle.
In severe or rigid curves the top and bottom screw may be left proud with up to two
threads exposed. This technique simplifies the rod-screw insertion without com-
A
Eurostile
25 ANTERIOR CORRECTION FOR THORACIC SCOLIOSIS
promising the pullout strength of the screw. Standing postoperative lateral x-ray
B
shows screws directed slightly anteriorly to ensure safe placement.
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Skin
incision
5
6
Curve
apex
7
8
9
10
11
12
Figure 25–3
The incision is made in the direction of the rib or intercostal space and carried
from the posterior angle of the rib to the costal-chondral cartilage.
Figure 25–4
Double thoracotomy through one skin incision. This approach allows for placement of proximal and distal screws in a rigid curve.
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SECTION II THE THORACIC SPINE
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Figure 25–5
The segmental vessels are identified and isolated by a Mixter or Addison. If the vessels are to be
spared, vessel loops are placed in the teeth of the instrument and passed beneath the vessels. The
vessels may then be mobilized and retracted without injury to allow placement of the screws. (See
Color Plate 25–5.)
Segmental vessels
retracted in loops and
disc material
removed
Figure 25–6
Removal of discs. After the annulus is incised, the nucleus is removed with a double-action rongeur. The discs are removed to the
vertebral end plates using a large, sharp elevator.
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25 ANTERIOR CORRECTION FOR THORACIC SCOLIOSIS
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Upper
vertebra
enlarged
Partially collapsed
lung retracted
Lateral
screw placement
Segmental
vessels
retracted
Lower
vertebra
enlarged
Screw
placement
Figure 25–7
Screw placement in the superior and inferior vertebral bodies is difficult. The technique of thoracoscopic stab wounds may be utilized to provide adequate access. A small
(쏝 3 cm) incision is made between the ribs to provide access for instrumentation and screw placement at these levels.
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SECTION II THE THORACIC SPINE
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Lateral rod in place
Bone graft
placed
Figure 25–8
Rod insertion. The rod is compressed over the convexity of the curve in a harmonious fashion. 4-mm Rod: Pre-bending of the rod
is not necessary and the rod rotation maneuver is not needed. 5-mm rod: The rod must be pre-bent and a rod rotation maneuver
is performed. Proximal or distal screw pullout may result with the loss of fixation at these regions.
Suggested Readings
Giehl J, et al. Biomechanics of three dimensional scoliosis correction. In:
Bridwell K, DeWald R, eds. The Textbook of Spinal Surgery. 2nd ed.
Philadelphia: Lippincott-Raven; 1997:627–640.
Haher T, Merola A, et al. Anterior Correction and Instrumentation for
Thoracic Scoliosis: Spinal Instrumentation Techniques. Vol. 2. Chicago: Scoliosis Research Society; 1998.
Harms J, Jeszenszky D, Beele B. Ventral correction of thoracic scoliosis. In:
Bridwell K, DeWald R, eds. The Textbook of Spinal Surgery. 2nd ed.
Philadelphia: Lippincott-Raven; 1997:611–626.
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25 ANTERIOR CORRECTION FOR THORACIC SCOLIOSIS
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26
Concave Thoracoplasty for Stiff Thoracic
Scoliosis
Peter Metz-Stavenhagen and Walter Morgenstern
Goals of Surgical Treatment
Release the curvature; reconstruct the thoracic deformity and sagittal profile for efficient correction of the deformity; horizontalize the end verte-
brae by distribution of distraction forces.
Diagnosis
Idiopathic thoracic scoliosis is defined as a lordotic deformity. The apex of
the curve is between T2 and T11-T12. Due to rotation, a rib-hump occurs
on the convexity of the curve with structural deformation of the rib. On the
concavity the ribs are bent anteriorly, producing the lordotic component of
the deformity. Other thoracic deformations are shoulder imbalance, waist
asymmetry. To establish the diagnosis, anteroposterior (AP) and lateral x-
rays of the spine are taken on a long cassette, as well as bending films, ex-
tension films, and rib-hump exposures.
Indications for Surgery
1. Pronounced thoracic scoliosis in adolescents and adults: stiff thoracic
curves (bending less than 50% correction)
2. Significant cosmetic deformation
3. Congenital thoracic curves [preoperative magnetic resonance imaging
(MRI) and myelogram mandatory]
Contraindications
1. Patients with severe pulmonary diseases
2. Patients with less severe thoracic deformity (rib-hump)
Advantages of Posterior Correction with Concave
Thoracoplasty
1. Increased correction of frontal plane deformity
2. Improved horizontalization of the end vertebra with superior cosmetic
results
3. Significant reconstruction of thoracic deformity (Figs. 26–1 and 26–2):
improved correction reconstruction of the profile
4. Rod closer to the center of gravity in the sagittal plane
5. Shorter fusion in comparison with conventional posterior scoliosis
surgery; increase of intrathoracic volume
6. Avoidance of combined procedure (anterior release and posterior correction)
Disadvantages
1. Overcorrection with imbalance
2. Shoulder asymmetry in stiff proximal thoracic curves
3. Increased blood loss in comparison to anterior procedures
4. Chest tube
complete horizontalization of the end vertebra on traction and bending
films, it is possible to use the lower end-vertebra (as in anterior procedures).
1. A typical posterior midline incision is made. The posterior vertebral
structures are exposed subperiosteally (Fig. 26–3A). The ribs on the
concavity of the curve are then exposed to allow subperiosteal stripping. From the third rib below the cranially instrumented vertebra
down to the 12th, the ribs are osteotomized close to the costotransverse
junction.
2. Instrumentation: Pedicle hooks or pedicle screws (extrapedicular) are
inserted into the first and second vertebrae cranially. Two or three
pedicle screws are inserted caudally (Fig. 26–3B).
Insertion of the Rod
A kyphotic pre-bent rod is used and connected to the hooks and screws.
The ribs are elevated and situated above the distraction rod (Fig. 26–4).
Compression is performed on the caudal segments to achieve a horizontal
situation of the lower instrumented vertebra and reconstruct the profile in
this area. A routine distraction maneuver is done cranially during a wakeup test. The rib ends are fixed over the rod (Fig. 26–4B). A second rod may
be inserted contralaterally with decent compression to increase primary
stability.Hooks are used cranially (2–3) placed on the transverse processes.
Caudally pedicular screws are used.
Pitfalls
1. Beware and identify the presence of any structural proximal thoracic
curves to avoid shoulder and neck imbalance. In these cases cranial fusion levels may have to be changed.
2. In combined scoliosis with pronounced structural lumbar curves, it
might be necessary to extend the fusion level to the lower lumbar endvertebra.
Complication of Instrumentation
Spinal imbalance secondary to a structural lumbar curve.
Postoperative Care
1. Chest x-rays every day until the chest tube is removed.
2. Chest tube may be removed when the drainage is less than 50 cc/24
hours.
3. The patient may be out of bed the first or second postoperative day;
ambulating is encouraged.
4. Postoperative TLSO is used for 3 to 6 months.
Procedure
Fusion Levels
The cranial and caudal levels are determined with preoperative traction
and bending films. Caudally this is generally one segment below the
neutral vertebra, cranially one above the neutral vertebra. In cases of
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SECTION II THE THORACIC SPINE
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Figure 26–1
Forward bending test demonstrating the clinical picture pre-
A
(A) and postoperatively (B), with corresponding x-rays of the
B
rib hump.
Figure 26–2
Anteroposterior (AP) x-rays pre- (A) and postoperatively
A
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26 CONCAVE THORACOPLASTY FOR STIFF THORACIC SCOLIOSIS
(B).
B
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