Thoracolumbar Deformity Advances

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1. Nonoperative Treatment of Thoracolumbar Deformity

Praveen V. MummanenP, Stephen L. Ondra0, Rick C. Sassoc a Department of Neurosurgery, Emory University, Atlanta, Ga., b Department of Neurosurgery, Northwestern University, Chicago, Ill., and c Department of Orthopaedic Surgery, Indiana University School of Medicine, Indiana Spine Group, Indianapolis, Ind., USA

The terms 'scoliosis, kyphosis, and lordosis' were first coined by the Greek physician Galen in the second century AD [1]. Since that time, significant advances have occurred in the classification and management of patients with spinal deformities.

Early physicians attempted to correct thoracolumbar deformities with nonoperative treatments. Hippocrates, and later Galen, unsuccessfully used longitudinal traction to try to pull the deformed spine back into alignment [2]. Ambrose Pare was the first physician to use an orthosis to brace a scoliotic patient (approximately 1,500 AD). Pare soon realized that bracing was not useful once a patient had reached skeletal maturity [1].

During the past several centuries, more sophisticated and effective nonoperative treatment modalities for spinal deformity have been developed.

Evaluation of Deformity

There are multiple causes of thoracolumbar deformity; a full discussion of all of these entities is beyond the scope of this chapter. We will limit our discussion to the most frequently encountered entities: adolescent idiopathic scoliosis, adult scoliosis, and thoracic hyperkyphosis. When the surgeon encounters any of these entities, the first step in the treatment paradigm is to evaluate the patient fully.

Measure Ilium
Fig. 1. Measurement of leg length from the umbilicus or the anterior superior iliac spine to the medial malleolus.

History

The patient's medical and family history should be documented. Documentation of the age of onset of the deformity and the rate of progression of the deformity are important factors that may influence treatment. Since the rate of curve progression often accelerates after puberty, the age of onset of menarche should also be noted. In addition, since spinal deformities can be inherited, it is important to identify all relatives with deformity and to attempt to classify the type of deformity and the rate of progression of the deformity in family members.

Physical Examination

Initially, a global survey is performed to evaluate overall spinal balance. Obvious curvatures are noted. Pelvic obliquities and abnormal skin folds are often seen with moderate to severe scoliotic curvatures. In the pediatric population, secondary sex characteristics are also noted. Additionally, in scoliotic patients, leg lengths are measured and discrepancies are noted. Leg lengths can be measured either from the umbilicus or the anterior superior iliac spine to the medial malleolus (fig. 1). In addition, overall coronal balance can be quantified in the upright position by dropping a plumb line from the C7 spinous process (fig. 2). Normally the line should extend down the intergluteal crease.

Patients with scoliotic curvatures may be in overall coronal balance if their secondary curves are of sufficient magnitude to recenter C7 over the inter-gluteal crease in the coronal plane. Patients are asked to perform side bends to assess if their curves are flexible or rigid.

Plumb Line Scoliosis

Fig. 2. C7 plumb line. Normally line should fall into intergluteal crease indicating coronal plane balance. The plumb line in this illustration falls to the right of the intergluteal crease indicating coronal plane imbalance.

In order to further evaluate scoliosis, the patient is asked to stand upright with their palms opposed in the 'praying position' and with their arms extended perpendicular to their torso. The patient is asked to bend forward at the waist until the shoulders and hips are in the same axial plane. The physician then views the patient from both the front and the back noting any spinal curvature or asymmetric rib/flank elevation. For lumbar curves, more forward flexion is required to bring out the maximal asymmetry; for thoracic curves, less forward flexion is required to bring out the maximal asymmetry. Some physicians elect to use an inclinometer to quantify their patient's scoliotic curvature. The patient is maneuvered to a flexed position where the asymmetry is most striking before the inclinometer is used.

Patients with kyphotic deformities are observed in the neutral position to see if they are able to look straight ahead when facing forward, and to assess for compensatory extension at the hips and flexion at the knees. In addition, these patients are asked to perform the forward bending test, which makes thoracolumbar apex kyphosis obvious. Finally, these patients are asked to extend and flex their spines at the apex of the curvature to check for curve flexibility.

Gibbus Kyphosis
Fig. 3. Postural and structural thoracic kyphosis. The illustration on the left shows a patient with a postural kyphosis. Note the rounded, smooth curve. The illustration of the patient on the right has a structural kyphosis with a pronounced gibbus in the midthoracic spine.

Kyphotic curves are classified as either postural or structural. Kyphotic curves that correct in extension are classified as postural. Postural kyphotic curves are smooth curves and are usually due to poor posture and not to a pathological process. Structural kyphotic curves, on the other hand, do not correct in extension, often have a sharp, angular gibbus at the apex of the curve on forward flexion, and are due to a pathological process (fig. 3).

Radiographic Evaluation

Standard radiographic evaluation for deformity begins with standing full length (36 inch) posterior-anterior (P/A) and lateral spine x-rays. In patients who cannot stand, recumbent x-rays are acceptable. The flexibility of the patient's scoliotic curve is evaluated with recumbent side-bending x-rays. Side-bending x-rays are taken in the recumbent position in order to avoid locking the facet joints during the bending motion. In patients who do not have adequate muscle mass to perform side bends, a manual push may be administered during the x-ray.

Scoliosis x-rays differ from nonscoliosis x-rays in several ways. First of all, they are shot in the P/A direction in order to minimize the radiation dose to the

Scoliosis Time

Fig. 4. The Risser classification (grades 0-5) is used to quantify skeletal maturity. Risser grade 1 patients have ossified only 25% of their iliac apophysis. Risser grade 4 patients have ossified 100% of their iliac apophysis, but have not fused their iliac wing to their ileum. Risser grade 5 patients are skeletally mature and have ossified their entire iliac apophysis and fused their iliac wing to the ileum.

Fig. 4. The Risser classification (grades 0-5) is used to quantify skeletal maturity. Risser grade 1 patients have ossified only 25% of their iliac apophysis. Risser grade 4 patients have ossified 100% of their iliac apophysis, but have not fused their iliac wing to their ileum. Risser grade 5 patients are skeletally mature and have ossified their entire iliac apophysis and fused their iliac wing to the ileum.

breast tissue in adolescent girls. Secondly, scoliosis x-rays are placed on the x-ray viewer in the opposite orientation from other x-rays. The reader looks at scoliosis x-rays as if he is looking at the patient's back, i.e. the right side of the x-ray is on the right side of the viewer.

In younger patients, special attention is paid to the pelvis on the P/A x-ray to assess skeletal maturity. In 1958, Risser [3] noted that the growth of the vertebral body endplate parallels the ossification of the iliac apophysis. The Risser classification (grades 0-5) is used to quantify skeletal maturity. Risser grade 1 patients have ossified only 25% of their iliac apophysis. Risser grade 4 patients have ossified 100% of their iliac apophysis but have not fused their iliac wing to their ileum. Risser grade 5 patients are skeletally mature and have ossified their entire iliac apophysis and fused their iliac wing to the ileum (fig. 4). Furthermore, the pelvic x-ray is examined to see if the triradiate acetabular cartilage is still open (indicating skeletal immaturity).

The lateral x-rays are inspected to assess overall sagittal balance. Normally, a plumb line dropped from the posterior vertebral body of C7 should pass through a point within 2.5 cm of the posterosuperior corner of S1. If the plumb line passes more than 2.5 cm anterior to this point, then the patient is noted to have a 'positive sagittal imbalance'. Likewise, if the plumb line passes more than 2.5 cm posterior to this point, then the patient is noted have a 'negative sagittal imbalance'.

The P/A x-rays are evaluated to assess coronal balance and rotatory deformity. Overall coronal balance is assessed by dropping a plumb line from the C7 spinous process. Normally, this line should pass through the midline of the sacrum.

Scoliosis Curve Direction
Fig. 5. Coronal, sagittal, and axial illustrations of a scoliotic deformity. Note that this single right thoracic curve has a significant rotatory component.

When there is a loss of coronal balance, as seen occasionally with scoliosis, the head and shoulders are no longer centered over the pelvis. In order to compensate, the patient often tries to bend the spine above or below the primary curve in the opposite direction. Over time, a fixed, secondary scoliotic curve can develop as a result of this bending. The apex of the secondary curve is opposite that of the primary curve, and the magnitude of the secondary curve is smaller than that of the primary curve.

Rotatory deformities result in loss of axial balance and often complicate scoliotic curvatures. They transmit loads unevenly between successive vertebral segments (fig. 5). Rotatory deformity can be evaluated on the P/A x-rays by assessing the symmetry in the pedicle positions at each level. Nash and Moe [4] classified the rotatory deformity by grading it from zero (no rotation) to grade IV (only one pedicle shadow is visible and it is rotated past the center of the vertebral body).

Plumb Line Posture Assessment

Fig. 6. Measurement of the Cobb angle. End vertebrae are the last levels that are tilted into the curve concavity. A line is drawn from the superior endplate of the superior end vertebral body, and another line is drawn from the inferior endplate of the inferior vertebral body. The angle of the intersection of these lines is the Cobb angle.

Fig. 6. Measurement of the Cobb angle. End vertebrae are the last levels that are tilted into the curve concavity. A line is drawn from the superior endplate of the superior end vertebral body, and another line is drawn from the inferior endplate of the inferior vertebral body. The angle of the intersection of these lines is the Cobb angle.

Curve Measurement

Scoliosis x-rays are evaluated to establish the number of curves, the location of the curve(s), the direction of the curve(s), and the magnitude of the curve(s). When multiple scoliotic curves are present, the major curve is defined as the largest, rigid curve. Minor curves are compensatory curves that are created to try to return to overall spinal balance. Minor curves are smaller than the major curve and usually are flexible on side-bending x-rays.

The magnitude of each coronal plane curve is quantified through the Cobb angle measurement. To measure the Cobb angle, the physician identifies the end vertebrae of the curve on the P/A x-ray. End vertebrae are the last levels that are tilted into the curve concavity. A line is drawn from the superior endplate of the superior end vertebral body, and another line is drawn from the inferior endplate of the inferior vertebral body. The angle of the intersection of these lines is the Cobb angle (fig. 6).

Indications for Treatment and Nonoperative Treatment Modalities

Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis is the most common form of scoliosis seen in the United States. School screening programs are effectively screening for this disorder, and the prevalence of scoliosis in the school age population is estimated to be 1-3% [5, 6]. Most patients with adolescent idiopathic scoliosis are female with a right thoracic curve. Patients with atypical thoracic curve patterns (i.e. left thoracic curve) also should be evaluated with spinal axis MRI to rule out other causes of adolescent scoliosis (i.e. tumor).

Indications for treatment are dependent on the initial Cobb angle, the skeletal maturity of the patient, and the progression of the curve. Skeletally immature patients (Risser score of 0-3) with curves less than 25° usually are not treated and are followed with serial x-rays at 4- to 6-month intervals to check for curve progression.

If the curve progresses to greater than 30° (but less than 40°), then nonoperative treatment with bracing is initiated [7]. For curves with their apex above T6, a cervical extension may be needed. Otherwise, underarm, rigid, thoracolumbar braces are satisfactory. Bracing requires cooperation and compliance from the patient and the family. Braces should be worn daily for over 18 h per day until skeletal maturity.

For braced patients, follow-up radiographs are obtained at 4- to 6-month intervals until skeletal maturity is reached. If the curve remains under 40° and the patient reaches the end of growth (Risser 4 status and at least 18 months since menarche), then the brace is discontinued. If the curve progresses beyond 40°, then surgical treatment is indicated [8, 9].

Adult Scoliosis

Adult scoliosis has two primary etiologies: adolescent idiopathic scoliosis (which has progressed after skeletal maturity) and degenerative adult-onset (de novo) scoliosis.

Adult Patients with Progressive Adolescent Idiopathic Scoliosis

Studies have shown that adolescent idiopathic scoliosis can progress after skeletal maturity, especially if the magnitude of the curve is greater than 30° [8, 10]. Consequently, it is important to continue to periodically follow patients with adolescent idiopathic scoliosis with curves greater than 30° at skeletal maturity. Patients with adolescent idiopathic scoliosis suspected of progressing during adulthood should be evaluated with serial scoliosis x-rays at 6-month intervals to document progression.

Adult patients with progressive adolescent idiopathic scoliosis typically become symptomatic in the fourth and fifth decades of life. These patients are usually female with thoracic or thoracolumbar junction curves. The most frequent presenting complaint in this patient population is back pain (lumbar more common than thoracic), and the etiology of the back pain may be multifactorial. Causes of back pain in this population include muscle fatigue, facet arthropathy, radiculopathy from foraminal compression, and lumbar degenerative disc disease. Other presenting complaints in this population include cosmetic deformity or, rarely, cardiopulmonary dysfunction.

For patients presenting with pain, the surgeon must deduce the cause of the pain via the patient's history, exam, and/or diagnostic testing. Fatigue-related back pain, for example, usually occurs on the convex side of the curve, is absent in the morning, worsens as the day progresses, and resolves with rest. It is often alleviated with physical therapy (strengthening of the back and abdominal muscles). If patients fail physical therapy, then bracing may be tried to reduce the workload on the muscles (bracing in the adult does not prevent curve progression).

Patients with facet arthropathy, on the other hand, often have pain on the concave side of their curve or in the lower lumbar spine. This pain is also activity related. Facet arthropathy can be confirmed by, and effectively treated by, facet joint injections.

Patients with thoracic or lumbar radiculopathy can be diagnosed by their history of radiating pain. The diagnosis can be confirmed by selective nerve root sleeve injection. The selective nerve root sleeve injections can be periodically repeated to give long-term pain relief.

Patients with degenerative disc disease causing mechanical low back pain should undergo a trial of physical therapy to strengthen their low back and abdominal muscles. This often alleviates their pain because these muscle groups can then function to decrease the workload of the lumbar discs. If physical therapy is ineffective, then further evaluation can be done with discography. If the discogram correlates with their pain and with disc degeneration seen on MRI, then lumbar fusion may be considered (if the patient is not osteoporotic).

For scoliotic patients presenting with pulmonary limitations, one key treatment option is cessation of smoking.

In general, initial management of adults with progressive idiopathic scol-iosis should be nonoperative. Most patients will respond to the measures above in combination with oral nonsteroidal anti-inflammatory medications.

Degenerative Adult-Onset Scoliosis

Patients with degenerative adult-onset scoliosis typically present during the sixth or seventh decade of life. These patients have primarily lumbar deformities, and the male to female ratio is equal. The presenting complaints are usually related to lumbar stenosis or extraforaminal stenosis with radicular pain and neurogenic claudication. Extraforaminal stenosis usually occurs at the apex of the scoliosis on the concave side as a result of the transverse processes abutting each other.

Low back pain may be due to facet arthropathy or degenerative disc disease. Discogenic pain commonly occurs below the scoliotic deformity in the 'normal' region of the lumbar spine because this region is compensating for the scoliotic curvature. Loss of lumbar lordosis (flat back) is common. The etiology of the low back pain must be ascertained. On physical exam, the facet joints can be loaded by asking the patient to extend the lumbar spine posteriorly and laterally; pain caused with this maneuver is indicative of ipsilateral lumbar facet arthropathy. Facet arthropathy can be confirmed by and treated with facet joint injections.

The workup and treatment for degenerative disc disease has been previously mentioned and will not be repeated here.

For symptoms of stenosis and radiculopathy, epidural steroid injections and selective nerve root sleeve injections may assist with the diagnosis and provide temporary relief from symptoms.

Kyphosis

Normal thoracic kyphosis ranges from 20 to 40°. Hyperkyphosis is a sagittal plane deformity with excessive flexion of the thoracic spine. Hyperkyphosis is subclassified as either postural or structural (fig. 3).

Postural kyphosis is due to poor posture, and the patient can consciously correct the curve by 'standing up straight'. Postural kyphosis is characterized by a smooth, rounding pattern in the thoracic spine. There is no gibbus on forward flexion. For patients with cosmetic issues related to their postural kyphosis, we recommend physical therapy with back strengthening exercises to improve posture. No operative intervention is indicated.

Structural kyphosis, on the other hand, cannot be consciously corrected by the patient. Often, a gibbus is seen when the patient is asked to flex forward, and there is often a sharp angular pattern to the kyphosis on x-ray. Structural kypho-sis can either be primary or secondary. The most common cause of primary structural kyphosis is Scheuermann's disease (juvenile kyphosis). Scheuermann's disease is defined as three consecutive levels of at least 5° of segmental kyphosis (anterior wedging) at each level [11]. The etiology of Scheuermann's disease is unknown; however, there does appear to be a familial occurrence. Nonoperative treatment for Scheuermann's disease is indicated for progression of the kyphosis beyond 40° (but under 70°) in a skeletally immature patient (Risser 1-4). For these patients, an underarm, hyperextension, thoracolumbar orthosis is often satisfactory to halt progression of the kyphosis [12, 13].

Secondary structural kyphosis, on the other hand, has an underlying pathological process. The most common etiologies include multiple level degenerative disc disease, vertebral body fracture or tumor, or prior multilevel laminectomy. Multilevel thoracic degenerative disc disease can result in thoracic hyperkyphosis, whereas multilevel lumbar degenerative disc disease is the most common cause of lumbar flat backs. Normally, lumbar discs are taller anteriorly than posteriorly and thus create lumbar lordosis. As the lumbar discs dehydrate, the lumbar spine loses this normal lordosis and becomes straight. The patient often loses overall spinal sagittal balance as a result and tries to compensate by flexing at the hips and knees. Patients with secondary structural kyphosis are often older adults, and the typical presenting complaint is back pain. The physician must, once again, determine the cause of the pain. The pain may be due to muscle fatigue, which typically worsens as the day progresses. Pain related to muscle fatigue can often be effectively treated by back strengthening physical therapy. Another treatment modality is daytime bracing with an underarm thora-columbar orthosis in those unable to perform back strengthening exercises. The orthosis can share the load with the posterior spinal musculature and reduce muscle fatigue and pain. However, in the skeletally mature patient, an orthosis will not prevent progression of the kyphosis. In addition, the orthosis can contribute to further weakening and atrophy of the lumbar musculature by shielding these muscles from spinal loads.

Pain may be due to degenerative disc disease (the workup and treatment have been previously mentioned and will not be repeated here). Pain may be due to facet arthropathy. This pain also tends to worsen as the day progresses. Facet joint injections can be both diagnostic and therapeutic for this problem.

Conclusion

For the majority of patients with mild or moderate spinal deformities, initial evaluation and a course (or several courses) of the appropriate nonsurgical treatment are often satisfactory to alleviate symptoms.

For those patients who fail to have relief of their symptoms with conservative treatment, and for those patients who have severe deformities, surgical intervention is often necessary. Part 2 will focus on the indications for surgical treatment and the options for surgical treatment of spinal deformity [14].

Acknowledgments

We are grateful to Drew Imhulse and Tom Fletcher for assistance with the radiographic images in the figures. We are grateful to Sherry Ballenger for editorial assistance.

Disclosure Statement

The following authors are consultants for Medtronic Sofamor Danek: Stephen L. Ondra, MD and Rick C. Sasso, MD.

References

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3 Risser JC: The iliac apophysis: An invaluable sign in the management of scoliosis. Clin Orthop 1958;11:111.

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5 Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061-1071.

6 Lonstein JE, Bjorklund S, Wanninger MH, Nelson RP: Voluntary school screening for scoliosis in Minnesota. J Bone Joint Surg Am 1982;64:481-488.

7 Nachemson A, Peterson L: Effectiveness of treatment with a brace in girls who have adolescent idiopathic scoliosis. J Bone Joint Surg Am 1995;177:815-822.

8 Weinstein SL, Ponseti IV: Curve progression in idiopathic scoliosis: Long-term follow-up. J Bone Joint Surg Am 1983;65:447.

9 Weinstein SL: Natural history. Spine 1999;24:2592.

10 Ascani E, Bartolozzi P, Logroscino CA, Marchetti PG, Ponte A, Savini R, Travaglini F, Binazzi R, Di Silvestre M: Natural history of untreated idiopathic scoliosis after skeletal maturity. Spine 1986;11:784-789.

11 Sorensen KH: Scheuermann's Juvenile Kyphosis. Copenhagen, Munksgaard, 1964.

12 Sachs BL, Bradford DS, Winter RB, Lonstein J, Moe J, Willson S: Scheuermann kyphosis. Follow-up of Milwaukee-brace treatment. J Bone Joint Surg Am 1987;69/1:50-57.

13 Murray PM, Weinstein SL, Spratt KF: The natural history and long-term follow-up of Scheuermann's kyphosis. J Bone Joint Surg Am 1993;75/2:236.

14 Mummaneni PV Ondra SL, Sasso RC: Thoracolumbar deformity advances. 2. Operative treatment of thoracolumbar deformity. Prog Neurol Surg. Basel, Karger, 2003, pp 225-239.

Praveen V. Mummaneni, MD

Assistant Professor, Department of Neurosurgery, The Emory Clinic 550 Peachtree St., Suite 806, Atlanta, GA 30308 (USA)

Tel. +1 404 686 8101, Fax +1 404 686 4805, E-Mail [email protected]

Haid RW Jr, Subach BR, Rodts GE Jr (eds): Advances in Spinal Stabilization. Prog Neurol Surg. Basel, Karger, 2003, vol 16, pp 225-239

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