Andrew P. White, James S. Harrop, and Todd J. Albert
DEFINITION
Adult scoliosis is a coronal deformity of the spine, typically also involving axial and sagittal plane abnormalities.
Adult scoliosis may be categorized by patient presentation.
One group, predominantly defined by lumbar stenosis and neurogenic claudication with degenerative deformity, has surgical management typically achieved by posterior lumbar procedures.
A second group, categorized by progressive deformity, with or without back pain, is more frequently treated with combination anterior and posterior procedures that may involve the thoracic spine to achieve surgical goals.
While the surgical principles and techniques used to address these different categories are similar, important variations exist.
ANATOMY
Anatomic characterization of adult spinal deformity involves the coronal, sagittal, and axial plane.
Lumbar degenerative scoliosis is characterized by loss of lordosis and intervertebral disc height, as well as listhesis in the anteroposterior, lateral, or rotary direction (fig 1A,B).
Long curves, typically the result of a preexisting spinal deformity, may involve the entire thoracolumbar spine and may be associated with a significant rotational component (fig 1C,D).
PATHOGENESIS
Adult scoliosis develops either as the progression of a spinal deformity that was present in adolescence, or as the development of a deformity related to other spinal disorders.
The progression of the adolescent spinal deformity is related to increasingly unbalanced forces in the axial skeleton over time.
De novo adult deformity is commonly the result of degenerative disease and may also be related to osteoporotic fragility fractures of the vertebrae, resulting in a deformity frequently associated with spinal stenosis and mechanical back pain.
NATURAL HISTORY
The progression of an adolescent deformity is often seen as a long thoracolumbar curve in the adult.
Curves that reach a magnitude of more than 50 degrees are more likely to progress, resulting in symptom exacerbation.
As patient age increases, curve flexibility decreases.
Lumbar degenerative curves typically involve fewer segments and may be limited to the lumbar spine.
Degeneration and deformity can cause central, lateral recess, and neural foraminal stenosis as a result of:
Loss of intervertebral height
Hypertrophy of facet joints
Buckling of the ligamentum flavum
Compression deformities
Neurogenic claudication, as well as radiculopathy and back pain, may result.
PATIENT HISTORY AND PHYSICAL FINDINGS
Determining the reason for the patient’s presentation is the first step in establishing the goals of surgical treatment.
Patients with extensive thoracolumbar deformity may present with concerns related to curve progression with an impact on:
Balance
Ambulation
Pain
Cosmesis
Patients with lumbar degenerative scoliosis classically present with complaints of neurogenic claudication.
Hip and knee flexion contractures, related to the typical forward-flexed ambulation that limits the symptoms of neurogenic claudication, may be found (fig 2).
Major focal neurologic abnormalities are unusual in this patient group, although relatively mild degrees of weakness in the tibialis anterior and extensor hallucis longus are not uncommon.
Physical examination should include the following:
Assessment of sagittal balance based on lateral observation of the patient standing with knees extended. A plumb line is dropped from the ear and the deviation (anterior or posterior shift) at the greater trochanter is measured, as is the regional (lumbar) lordosis and (thoracic) kyphosis. An upright posture with head over trunk and trunk over pelvis is a critical treatment goal.
Assessment of coronal balance based on posterior observation of the patient standing. A plumb line is dropped from the occiput and the deviation (leftward or rightward shift) at the sacrum is measured. A centered posture reduces gait abnormality.
The clinician should observe and palpate the vertical relationship of the right and left acromions with the patient standing. Shoulder asymmetry may indicate coronal postural compensation to maintain upright stance.
The clinician should observe and palpate the vertical relationship of the right and left iliac crests with the patient standing on the right, left, and both legs. Pelvic obliquity may be a primary or compensatory mechanism with spinal deformity.
Assessment of hip and knee range of motion. Longstanding sagittal plane deformities, as well as neurogenic claudication, may result in hip and knee flexion contractures.
Focal findings may be uncommon, but a thorough neurologic examination must be performed.
FIG 1 • A,B. Degenerative lumbar scoliosis in PA (A) and lateral (B) radiographs. Lateral, rotary, and anterolistheses are seen, with significant loss of disc height, osteophyte formation, and subchondral sclerosis. The coronal deformity is limited to the lumbar region. C,D. A long scoliosis involving the lumbar and thoracic regions, associated with rotational deformity, shown in PA (C) and lateral (D) radiographs.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Radiographs
Standing posteroanterior (PA) radiographs on 36-inch cassettes characterize the spinal deformity by:
The magnitude of primary and compensatory curves, by the Cobb method (fig 3)
Coronal balance: the relationship between the C7 plumb line and center of S1 on PA views (fig 4)
FIG 2 • Neurogenic claudication is frequently associated with this gait abnormality. A forward-flexed posture may provide postural relief of posterior foraminal stenosis but typically alters the sagittal balance, as depicted here. Hip and knee flexion contractures may be associated.
The apical vertebrae (most laterally deviated; FIG 5A)
The stable vertebra (caudal vertebra that is transected by the z axis; FIG 5B)
Rotary and lateral listhesis
Standing lateral radiographs on 36-inch cassettes characterize the spinal deformity by:
Regional lordosis and kyphosis (fig 6)
Sagittal balance; the relationship between the C7 plumb line and center of S1 on lateral views (fig 7)
Anterolisthesis or retrolisthesis
FIG 3 • The Cobb method is used to measure the coronal deformity. Vertebral endplates (or the margins of pedicles) are used to extend lines as depicted for each of the curves involved. Lines orthogonal to these are then compared to determine the scoliosis angle. Vertebrae are typically selected to maximize the Cobb angle on each measurement.
FIG 4 • Coronal balance is evaluated on the standing PA radiograph. A virtual plumb line is dropped from the center of C7. The lateral distance between that plumb line and the center of S1 is then measured. (Left to right) Negative coronal decompensation, coronal compensation, and positive coronal decompensation. CSVL, center sacral vertical line.
FIG 5 • A. The apical vertebra is defined as that which is most deviated laterally on the PA radiograph. B. The stable vertebra is defined as the caudal vertebra that is transected by the vertical plumb line extending from the center of S1 on the standing PA radiograph. CSVL, center sacral vertical line.
FIG 6 • Regional lordosis and kyphosis are measured on the standing lateral radiograph. Typically the vertebral endplates are used as references for measurement.
Rightand left-bending PA radiographs (fig 8) are used to:
Evaluate spinal flexibility
Determine the structural or nonstructural nature of the curve
Supine traction radiographs may also be used to evaluate curve flexibility.
CT Scans
Axial CT images, reformatted in the plane of the superior endplates of each vertebra, may be used to measure pedicle dimensions for preoperative planning.
Plain radiographs and CT images can be used to assess the degree of bone loss and tailor the reconstructive techniques to the bone quality of the patient.
MRI
MRI is used to assess neurologic compression (fig 9) as well as the status of the disc, ligamentum flavum, and other soft tissues.
Dual-Energy Radiographic Absorptiometry
Dual-energy radiographic absorptiometry (DEXA) is often performed for patients with identified risk factors15:
History of fracture as an adult or fracture in a first-degree relative
FIG 7 • Sagittal balance is evaluated on the standing lateral radiograph. It is measured as the anterior (positive) or posterior (negative) distance between the C7 plumb line and the center of the L5-S1 disc space.
FIG 8 • Bending radiographs aid in determining the flexibility of the spinal curves and are also used to determine the structural or nonstructural nature of the curves.
White race
Advanced age
Smoking
Low body weight
Female gender
Dementia
Poor health or general fragility
Provocative Tests
Discography can be useful to assess for painful segments, particularly in the lower lumbar spine.
Facet blocks have been employed to determine levels that should be included, or need not be included, in the fusion. This may be particularly relevant at the lumbosacral junction.20
NONOPERATIVE MANAGEMENT
A physical therapy regimen may be tried, focusing on:
Stretching and core-strengthening exercises
Postural training
Gait training
Resolution of hip and knee flexion contractures
General conditioning
Nonsteroidal anti-inflammatory medications may be used if safely tolerated
SURGICAL MANAGEMENT
The treatment of adult scoliosis is complex because of the global nature of the spinal deformity and the multiple causes of this disorder.
Efficiency, safety, and effectiveness in meeting surgical goals are each optimized by a well-designed procedure.
Preoperative Planning
Preoperative planning is instrumental to a successful treatment algorithm; avoiding both shortand long-term complications is paramount.
In 1968, the complications associated with surgical correction of adult deformity were estimated to include31 :
5% risk of death
6% risk of major neurologic deficit
20% risk of correction loss
10% risk of deep infection
40% risk of major medical complication
FIG 9 • MRI is particularly useful in evaluating patients with neurologic symptoms such as claudication. It is used to assess neurologic compression as well as the status of the disc, ligamentum flavum, and other soft tissues.
With advances in surgical and anesthesia techniques, neurophysiologic monitoring, and improvements in perioperative management, these risks have been significantly decreased.2
The patient with adult scoliosis may carry a myriad of comorbidities that may increase the risk of a spinal operation or even contraindicate it. A complete preoperative assessment of those considering surgical treatment provides the opportunity to minimize risks by optimizing health status.
Modifiable conditions that affect surgical risk include:
Tobacco smoking40
History of asthma or chronic obstructive pulmonary disease38
Coronary or cerebrovascular disease1,27
Diabetes29
Nutritional deficiency18,30
Osteoporosis3,23
Depression34
Current significant life stressors6
Collaboration with consulting medical specialists who are trained in perioperative management is an important technique to optimize outcomes for patients with adult scoliosis.
Anesthesia colleagues familiar with this surgical course may also reduce risks.
Certain medical considerations directly affect the selection of surgical techniques for a patient with adult scoliosis.
Assessment of bone quality plays a critical role in the design of the operation.
Osteoporosis is the rule, not the exception.22
Approach
Posterior surgical approaches are typically used for the treatment of adult deformity correction.
Anterior surgery may be used alone in isolated cases but is more frequently combined with posterior surgery to augment the deformity correction, reconstruction, or both.
Anterior exposure allows the soft tissue releases that are often required for adequate deformity correction.
General Procedures
Fixation Strategies for Osteoporotic Bone
Spinal instrumentation with pedicle screw fixation is less effective in osteoporotic bone.8,14
Trabecular bone is predominantly affected by osteoporosis.
Since pedicle screws have cortical contact limited to the pedicle isthmus, a “windshield wiper” mode of failure typically leads to screw loosening.24
Fixation strategies for osteoporotic bone are targeted toward:
Taking advantage of the relatively stronger cortical bone7
Augmenting the fixation of a pedicle screw within the existing trabecular bone39
Bone-implant interface complications in the osteoporotic spine can be reduced by various methods.
Sublaminar wires and pediculolaminar fixation16 take advantage of the cortical bone composition of the posterior spinal lamina (fig 10).
Fixation of pedicle screws within osteoporotic trabecular bone may be improved by polymethylmethacrylate (PMMA) cement augmentation.36
Fluoroscopy is used to visualize the placement of 2 to 3 cc of PMMA per pedicle to ensure that cement does not migrate to the neural elements.
FIG 10 • Fixation strategies for osteoporotic bone may include the use of multiple fixation points in a vertebra. Such instrumentation, as depicted here, incorporates pedicle screw and laminar hook instrumentation at the same vertebral level.
Calcium sulfate paste may also be used; this has the theoretical advantage of becoming replaced by bone over time.35
Modified pedicle screws may also be used, including conical screws, hydroxyapatite-coated screws, and expandable screws.
PEDICLE SCREW ELECTION AND PLACEMENT
Screw pullout strength is improved when high insertional torque is achieved42 by:
Undertapping (or not tapping) the screw path
Using tapered screws. These are limited by the absolute restriction that they cannot be reversed or backed out; such an action would remove the screw’s contact with the bone.
Using larger-diameter screws. Increased cortical contact may increase insertional torque but may increase the risk of pedicle fracture as well.
Using longer screws: Bicortical purchase can increase screw pullout strength but may pose the possibility of injury to abdominal or vascular structures.
Fusion and Bone Grafting
Establishment of a solid fusion is critical.
The pseudarthrosis rate in one large series of adult deformity patients after long fusion procedures was 24%. Statistically significant risk factors for pseudarthrosis in that study included17 :
Thoracolumbar kyphosis
Hip osteoarthritis
Use of a thoracoabdominal (versus paramedian) approach
Positive sagittal balance greater than 5 cm
Age greater than 55 years
Incomplete sacropelvic fixation
These risk factors emphasize the importance of surgically establishing the proper mechanical environment, including overall sagittal balance and appropriate fixation.
BONE GRAFT SELECTION
Appropriate graft selection may reduce pseudarthrosis risk.
Bone grafts and alternatives may serve multiple roles in the surgical treatment of adult scoliosis; fusion-promotion and deformity-correction techniques both may influence graft selection.
An anterior interbody graft may need to be structural to correct a deformity.
If a structural graft is used anteriorly first, it is with the anticipation that further deformity correction at that segment will be limited by posterior manipulation.
Anterior structural interbody grafts can be instrumental in preventing a kyphosis when the convexity of a deformity is compressed in a reduction maneuver.
Structural grafts can be placed with a bias toward the concavity in order to assist in the deformity correction.
Structural interbody grafts serve a critical role in supplementing the stability of a reconstruction, particularly at the caudal end of a construct, at the lumbar–sacral junction.
Morselized grafts may allow for deformity correction by subsequent posterior manipulation.
Our typical strategy is as follows:
Use structural grafts at the caudal end of the construct (two to four levels).
Overzealous posterior manipulation can cause loosening or displacement of an anterior structural graft.
Use morselized graft rostrally.
Subsequent deformity correction during the posterior procedure will be limited mainly to those levels with morselized (or no) anterior graft.
INTERBODY GRAFT MATERIALS
Graft selection is guided by:
The goal of fusion success
The potential utility of structural roles for the graft
The risk of potential complications and other shortcomings
Costs
Interbody grafts may be composed of:
Bone (autograft or allograft)
Metal
Carbon fiber
PEEK
Other synthetic material
To reduce the risk of graft subsidence, a graft with a modulus of elasticity similar to that of the native bone can be employed.
Iliac crest autograft is typically the best modulus match but is associated with well-established harvest-related morbidity.
In osteoporosis, we have used allograft harvested from the iliac crest of a donor, which offers:
A relatively high proportion of trabecular to cortical bone compared to a long bone allograft, and an improved modulus match
More rapid biologic incorporation of trabecular grafts
Carbon fiber and PEEK interbody cages offer a lower (and more closely matched) modulus compared to metal cages; we typically avoid metal cages in the reconstruction of osteoporotic spinal deformities.
Autograft remains the gold standard material for establishing a solid arthrodesis but has shortcomings:
Morbidity of iliac crest autograft harves.
Chronic donor-site pain
Postoperative hematoma, infection
Nerve or vessel injury
Iliac graft harvest may be undesirable when iliac instrumentation is planned.
Autograft may be insufficient for an extensive thoracolumbar fusion.
Autograft alternatives include allograft products, synthetics, and bone morphogenetic proteins (BMP).
The fusion efficacy of BMP-2 has recently been demonstrated in patients with adult spinal deformity.
Seventy adult patients underwent scoliosis fusion with anterior or posterior BMP-2 application, with either local bone graft only (posterior) or no bone graft (anterior), obviating rib, iliac crest, or other autograft harvest morbidity.
Fusion rates were satisfactory, with 96% anterior fusion success and 93% posterior fusion success.26
BONE MORPHOGENETIC PROTEIN
Attention to certain surgical techniques reduces the risk of complications and may also improve efficacy.
The risks associated with the use of BMP in the cervical spine include41 :
Complications related to soft tissue swelling
Inappropriate bone formation
Accelerated graft resorption
In the lumbar spine, there also have been reports of undesirable effects, including:
Inappropriate bone formation around neural elements28
Postoperative radiculitis
Accelerated resorption of interbody grafts, increasing the risk of pseudarthrosis, has also been reported in a study of single-level uninstrumented anterior lumbar interbody fusion.33
Structural allograft with appropriate doses of BMP at the lower two to four levels in adult thoracolumbar fusions can, however, be used with minimal risks of complications.
Example: BMP-augmented transforamimal lumbar interbody fusion (TLIF)
Care is taken to reduce the risk of inappropriate bone formation.
These steps may help ensure maintenance of the BMP and limit the BMP from affecting adjacent tissues:
Irrigate before the placement of the BMP packed cage, not afterward.
Pack the BMP sponge entirely within the cage, avoiding “overstuffing.”
Place additional sponge only anterior to the cage.
Use a repairable “trapdoor” annulotomy.
A three-sided annular flap is created, hinging medially, such that when the flap is held open with sutures at its corners, it augments the protection of the thecal sac.
After discectomy and placement of BMP, anterior graft, and TLIF cage, the annulotomy is repaired with suture and augmentation of the closure with an adjuvant sealant.
Sagittal Balance
The single most important principle in the surgical treatment of adult scoliosis is achieving and maintaining a proper sagittal balance.
Balanced spinal posture with neutral positioning:
Provides for decreased energy requirements with ambulation
Limits pain and fatigue
Improves cosmesis and patient satisfaction
Limits complications associated with unresolved (or new) deformities
FUSION LEVEL SELECTION
Sagittal balance must be achieved.
Junctional problems must be avoided.
Presenting symptoms can guide level selection.
Discography can be useful to assess for painful segments, particularly in the lower lumbar spine, that may be incorporated in the fusion.
Facet blocks have been employed to determine levels that should be included or need not be included. This may be particularly relevant at the lumbosacral junction.20
RADIOGRAPHS
36-inch standing PA and lateral
PA (left and right) bending views, to determine if the main curves are structural
If the Cobb angle is greater than 25 degrees on side-bending radiographs, then it is considered to be a structural curve.25
Curve magnitude and flexibility and the apical vertebral translation of the thoracic and lumbar curves are measured.
The relationship between the C7 plumb line and the center sacral vertical line is considered.
Radiographic signs of degenerative disease are categorized.
Listheses (rotary and lateral) are noted. Degenerative segments often are associated with stenosis; this must be considered in the treatment algorithm.
FUSION TO THE SACRUM
Extension of the fusion to the sacrum for the adult scoliosis patient is an important and controversial subject. There is no consensus as to the best strategy for all clinical scenarios, but certain guidelines and lessons have been developed.
There is a relatively high rate of pseudarthrosis (and other complications) after L5–S1 fusion.11,19 For these reasons, in part, some have advocated avoiding fusion to the sacrum whenever possible.5
Certain scenarios do require lumbosacral fusion:
Symptomatic L5–S1 spondylolisthesis
Other instability
Oblique take-off with over 15 degrees of scoliosis at the L5–S1 segment often requires reduction and fusion for adequate correction of deformity.
For correction of lumbar hypolordosis to achieve proper sagittal balance
The risk of pseudarthrosis at the lumbosacral junction can be limited by:
Employing combined approaches to perform a meticulous 360-degree fusion at the L5–S1 segment
BMP may be applied to further increase the chances of solid arthrodesis.
Anterior instrumentation has been advocated:
Fixed-angle plates
Vertebral body compression screws
Isolated posterior instrumentation may be satisfactory if good bicortical purchase is achieved with sacral screws, with high insertional torque.
Additional fixation is required, however, in many cases, and iliac screws or Galveston technique fixation satisfies this need.
Recently, the use of allograft with BMP and posterior pedicle fixation, without iliac fixation, has been used successfully due to the speed of healing, with the caveat that this depends on the length of fusion.
Specific Management Strategies by Diagnosis
Degenerative Lumbar Scoliosis
The patient with adult lumbar scoliosis typically has some component of back pain and may also present with radiculopathy or claudication.
For the typical patient presenting with stenosis complaints, decompression of the neural elements is a priority.
Deformity correction with proper sagittal balance also is a critical goal of surgery.
Loss of lumbar lordosis is associated with increased pain.37
Restoration of proper sagittal balance is the most important factor associated with clinical outcome.13
The typical patient presents with hypolordosis and varying degrees of scoliosis, typically associated with relatively flexible thoracic compensatory curves less than 30 degrees or no thoracic curve (fig 11A,B).
Common radiographic findings include:
Degenerative disease, most commonly at L5–S1
Rotary subluxation at L3–L4 (fig 11C,D)
Obliquity at L4–L5 (fig 11E,F)
The choice of surgical approach for the treatment of lumbar adult scoliosis depends on:
The levels of the pain-generating segments
The flexibility of the curve
The coronal obiquity of the distal vertebrae
The extent of the curve
While in situ fusion may be an option for patients with small-magnitude deformity and poor bone quality, typically restoration of lordosis and coronal realignment are desired (fig 12). This can be accomplished with a variety of methods, many of which require restoration of anterior height.
TLIF for Deformity Correction and Reconstruction
TLIF may achieve these goals with a posterior-only approach.
To assist in correction of the deformity, the cage may be biased to the concavity of the scoliosis to address the coronal plane.
After facetectomy and posterior compression, lordosis can be restored.
In general, a posterior interbody technique (posterior or thoracic lumbar interbody fusion) is less effective than an anterior interbody approach for restoring lordosis.
The use of an operating table that produces extension of the lumbar spine (Jackson) to maximize positional lordosis is critical.
The decision of the levels to include in the treatment of a degenerative lumbar deformity may be determined by a variety of influences.
It can be useful to preoperatively determine which segments contribute to a patient’s pain.
The apex of the deformity is included (typically L3 or L4).
Levels that are severely degenerated may also be included, particularly if they exhibit lateral or rotary listhesis.
There is no general consensus as to where a lumbar construct should terminate cranially, but it should be at least at a stable end vertebra (ie, the cranial-end level of the fusion construct should be bisected by the center sacral line on a lateral radiograph).
If the goal is to treat neurogenic claudication, relieve stenosis, and prevent future progression, a short-segment construct (often L2–L5) is sufficient if adequate lordosis is attained and the cranial and caudal vertebrae are well balanced.
FIG 11 • A,B. Radiographs of a patient with degenerative lumbar scoliosis. Rotatory and lateral listheses are seen on the PA view (A) and the typical hypolordosis is seen on the lateral view (B) preoperatively. C,D. Lumbar radiographs of a typical patient with degenerative scoliosis limited to the lumbar region. The lateral listhesis is seen at L3–L4 (C) as well as the typical loss of lumbar lordosis (D). In another patient, obliquity at L4–L5 is seen in the preoperative PA radiograph (E), with focal loss of disc and neuroforaminal height seen on the preoperative lateral radiograph (F).
In many scenarios, however, such as when the Cobb angle is from L1 to L5, it is necessary to continue the fusion cranially past the thoracolumbar junction.
When this is the case, one should take care not to end the fusion at the thoracolumbar junction or at the apex of the thoracic kyphosis.
Extending the fusion to the thoracolumbar junction provides fixation into the more stable rib-bearing vertebrae and is more likely to terminate within the sagittal plumb line, reducing the risk of instrumentation failure or junctional kyphosis.
A frequent decision-making dilemma is where to end the caudal end of the fusion reconstruction.
FIG 12 • A,B. After decompression of the patient in Figure 11A,B, spinal reconstruction is achieved with recreation of coronal (A) and sagittal (B) balance. C,D. In the patient in Figure 11E,F, postoperative reconstruction after decompression of the neural elements recreates lumbar lordosis to achieve proper sagittal balance.
FIG 13 • These standing radiographs were performed on 36-inch cassettes before and after scoliosis fusion from T4 to the ileum. A,B. Iliac fixation was motivated, in part, by the obliquity at the lumbosacral junction. Concerns related to this patient’s osteoporosis led the surgeons to use a combination of fixation techniques, including pedicle screw fixation and sublaminar wiring, to take advantage of the relatively well-preserved cortical bone. There is restoration of coronal (C) and sagittal (D) balance.
Accepted indications to fuse to the sacrum include4 :
Spondylolisthesis or previous laminectomy at L5–S1 (fig 13A)
Stenosis requiring decompression at L5–S1
Severe degeneration
An oblique take-off (above 15 degrees) of L5 (fig 13B)
Fusions to the sacrum in adults with lumbar scoliosis have been found to:
Require more additional surgery than those to L5
Have more postoperative complications
On the other hand, fusions to L5 have been associated with:
A 61% rate of adjacent segment disease
An associated shift in sagittal balance12
When fusion to the sacrum is performed, iliac fixation should be considered, particularly if the fusion includes more than three levels (fig 13C,D).
Augmentation of the lumbosacral reconstruction with interbody fusion at L5–S1:
Improves biomechanical stability32
Reduces the risk of lumbosacral pseudarthrosis21
A structural graft at L5–S1 can:
Recreate lordosis, partially restoring sagittal balance
Diminish stenosis by restoring intervertebral height
Hip and knee flexion contractures can be common in this group, with patients accustomed to ambulating with flexed posture.
A flexion contracture at the hip limits the patient’s ability to extend the sagittal plumb line posterior to the hips.
It may be necessary to address the patient’s hip pathologies before planning any surgical correction of a spinal deformity.
Thoracic and Lumbar (Double-Curve) Scoliosis
Patients with double major adult scoliosis may present with axial skeletal pain.
Complaints of progressive deformity may be manifested as:
Changes in balance
Gait abnormalities
Alterations in cosmesis
The surgical treatment of double-curve scoliosis often combines anterior and posterior procedures (fig 14).
Long deformities that are relatively inflexible may require anterior releases to accomplish effective reduction and fusion with posterior surgery.
In part because of the typical degeneration in adult patients, fusions into the caudal lumbar spine are more frequently required.
Bending films determine whether the lumbar flexibility is adequate for the scoliosis to “bend out” (see Fig 8).
Curve stiffness is related to both patient age and curve magnitude.
Flexibility decreases by 10% with every 10-degree increase in coronal deformity beyond 40 degrees.
Flexibility decreases by 5% to 10% with each decade of life.9
The correction of a double-curve deformity can be accomplished with a variety of methods. The primary goal of achieving a proper sagittal balance must be emphasized. Reduction of the coronal and rotational deformities follows in priority, with the goal of establishing coronal balance and reduction of rib asymmetry for enhanced cosmesis and patient satisfaction, if possible.
FIG 14 • This long thoracolumbar scoliosis was treated with a fusion from the upper thoracic spine to L5. To reduce the risk of pseudarthrosis at the caudal end of the construct and to assist in the recreation of lordosis, structural interbody grafts were placed in the three most caudal disc spaces of the fusion, with morselized graft above, after releases of the anterior interbody soft tissues were performed. Subsequently, a posterior fusion was performed with pedicle screw instrumentation.
Analogous to the design of the operation for adult lumbar deformities, the decision of whether to extend the fusion to the sacrum may be difficult.
Lumbosacral fusion is recommended when5 :
Decompression of L5–S1 stenosis is required
There is a fixed obliquity over 15 degrees at L5–S1 (see Fig 13B)
Long fusions to the sacrum increase the risk of pseudarthrosis and reoperation. These may be minimized by anterior augmentation and iliac fixation, as previously discussed (see Fig 14).
The cranial end of the fusion should include the thoracic curve and should not stop caudal to any structural aspect of it.
All fixed deformities and subluxations should be included in the fusion.
Rod cross-links increase the stiffness of long constructs10 and are recommended (see Fig 14C). They should be avoided at the thoracolumbar junction; however, where they may increase the risk of pseudarthrosis.17
Vertebral derotatio.
Curve stiffness may limit the surgeon’s ability to reduce the rotational deformity in the adult population.
For relatively flexible rotational deformities, rotational reduction can be achieved with effective improvement in trunk symmetry, which can significantly improve patient satisfaction (fig 15).
Additional release maneuvers may be necessary in stiff curves, including thoracoplasty, concave rib osteotomies, and aggressive facetectomies.
FIG 15 • A,B. Monoaxial or uniaxial screws are placed into the pedicles of the vertebrae that will be manipulated. C,D. After one prebent rod (usually the left rod by convention) is placed and rotated in the usual manner to reduce the coronal deformity and attain a proper sagittal relationship, it is locked to screws at the thoracolumbar junction and at the cranial and caudal limits of the construct. Reduction tubes are then placed onto the fixed screws at the thoracolumbar junction, which we refer to as the “mainland” for purposes of the reduction. E. An array of tubes is placed onto the screws of the thoracic cascade, where the greatest rotational deformity typically exists. F. These secondary tubes are then aligned toward the mainland vertebrae, effecting the rotational reduction, and locked to the rods. G. Rotational reduction is then applied one vertebra at a time in the lumbar region, caudal to the mainland, since the lumbar lordosis often limits the application of more than one set of reduction tubes concurrently. H. The prebent contralateral rod is then placed and locked to screws at the thoracolumbar junction as well.
POSTOPERATIVE CARE
If a brace is used, it must be custom-molded postoperatively, after surgical deformity correction is accomplished.
Application of a preoperatively molded brace is counterproductive and should be avoided.
Postoperative physical therapy regimen should focus on:
Range-of-motion and flexibility improvement, often in response to chronic hip and knee loss of motion or contractures
Gait training, to include balance rehabilitation
General conditioning
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