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Degenerative (De Novo) Adult Scoliosis
Degenerative (De Novo) Adult Scoliosis Khaled M. Kebaish, MD De novo scoliosis is a term used in adult patients who have no history of scoliosis as adolescents but then develop a coronal plane deformity that is associated with degenerative changes in the spinal column. It rarely presents before 40 years of age. Differentiation from degenerative idiopathic scoliosis may be difficult. The coronal curve usually involves the lumbar and less commonly the thoracolumbar junction. Osteoporosis, degenerative disk disease, compression fractures and spinal canal stenosis have all been implicated in the development of degenerative scoliosis. Patients with degenerative lumbar scoliosis present with complaints ranging from debilitating back or lower extremity pain and spinal imbalance to incidental findings on lumbar radiographs. When surgical treatment is indicated, careful preoperative evaluation and surgical planning should always be done. There are increased risks of complications in this population. The deformities are often more rigid; however extensive posterior release in addition to solid pedicle fixation will allow the surgeon to address most of these deformities through a posterior approach. Anterior approach may be reserved to add structural support at the lumbosacral junction. Despite the high risk of complications in patients undergoing reconstructive surgery for de novo scoliosis, most studies suggest a significant improvement in quality of life and a high rate of patient satisfaction. Semin Spine Surg 21:7-15 © 2009 Elsevier Inc. All rights reserved. KEYWORDS de novo scoliosis, degenerative scoliosis, surgical outcome in adult scoliosis, adult spinal deformities, adult idiopathic scoliosis
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e novo scoliosis is a term used in adult patients who have no history of scoliosis as adolescents but then develop a coronal plane deformity that may be of a progressive nature and is associated with degenerative changes in the spinal column. Degenerative scoliosis rarely presents before 40 years of age. It has been referred to as “collapsing scoliosis,”1 “de novo adult scoliosis,” and “senescent lumbar scoliosis.”2 How often this occurs is unknown. Differentiation from degenerative idiopathic scoliosis may be difficult. The coronal curve usually involves the lumbar and less commonly the thoracolumbar junction. The lumbar curve is often a dual curve with a larger one in the proximal lumbar spine, with the apex at L2 or L3. It rarely exceeds 60°. Degenerative changes always affect the facet joints and the intervertebral discs and the curves are commonly associated with loss of lumbar lordosis (Fig. 1). Department of Orthopaedic Surgery, Johns Hopkins University, Johns Hopkins Outpatient Center, Baltimore, MD. Address reprint requests to Khaled Kebaish, MD, Department of Orthopaedic Surgery, Johns Hopkins University, Johns Hopkins Outpatient Center, 601 N. Caroline Street, Suite 5243, Baltimore, MD 21287-0882. E-mail: [email protected]
1040-7383/09/$-see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1053/j.semss.2008.11.002
The only certain proof that a patient has a new curve, rather than a progression in a previously unrecognized curve (Fig. 2), is a normal spinal radiograph sometime at a younger age. Therefore, an accurate estimate of the prevalence in the population is not possible to determine. Vanderpool et al3 were among the first to study this problem carefully. Their control group, which averaged 61.4 years of age, had a prevalence of 6%, but most curves were small (7°-16°). A similar finding was observed in adult relatives of patients with scoliosis. An osteoporotic group showed 36% with curvature. The average age was 71 years. They were able to identify 14 of the 36 patients who had unequivocal evidence of having been free of scoliosis at an earlier age. The average age of onset was 40 years. An episode of back pain was usually the identified point at which scoliosis began. The curves were, in general, mild and ranged from 7° to 53°. They found that the distribution of involvement in all levels of the spine was equal. A similar finding was present in 24 patients with osteomalacia; 38% had a curvature, but it was generally mild, and had little or no rotation. Because of this analysis, they concluded that adult-onset curves were secondary to osteomalacia and osteoporosis. However a recent study showed no correlation between osteoporosis and the prevalence of scoliosis.4 7
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Figure 1 AP and lateral radiographs of a 67-year-old lady with de novo scoliosis showing loss of lumbar lordosis.
A different perspective was proposed by Robin et al.5 They followed a group of 554 subjects for intervals of 8-13 years. Some degree of scoliosis was found in 70% of subjects, and 30% had curves of greater than 10°. Ten percent of their patients developed scoliosis in the follow-up interval. However, they concluded that there was little relationship to progression, osteoporosis, or degenerative changes in the spine. Their conclusion was interesting: “Since scoliosis in the elderly seldom becomes a clinical problem of significance, there would appear to be no valid reason for more extensive study of this condition at this time.” Their conclusion is striking in its contrast to the experience of Epstein et al,2 Benner and Ehni,6 Grubb,7-9 and Perennou et al10: that scoliosis occurs de novo in adults, is probably degenerative in etiology, and can be the source of significant symptoms. Attempts to differentiate the adults with pre-existent but progressing scoliosis from those with a new curve have been made by Grubb.7-9 Significant differences and similarities were identified.11 All of the idiopathic group were females with a mean age of 42; however, the sex distribution was equal in the degenerative group, and the mean age was older at 60 years. Low back pain incidence was in both groups, radiating into the buttock and upper thighs. Although 90% of subjects with degenerative curves had symptoms suggestive of spinal stenosis, only 31% of the idiopathic group had such pain.
Etiology Osteoporosis, degenerative disc disease, osteoarthritis, compression fractures, spinal canal stenosis, endochondral abnormalities, and facet tropism have all been implicated in the development of degenerative scoliosis.12-14 None have been shown to be directly related. In fact, little is known about the etiology of degenerative scoliosis. In 1969, Vanderpool et al3 reported that the incidence of degenerative scoliosis was 36% in patients with osteoporosis
Figure 2 (A) AP lumbar radiograph of a female patient at age 32. (B) Same patient presenting with severe scoliosis at age 64.
De novo scoliosis and 38% in patients with osteomalacia, 6-fold higher than in age- and sex-matched controls. The authors suggested that the higher prevalence of scoliosis in patients over age 50 implicated osteoporosis as the cause of the deformity. Bridwell15 reviewed 48 patients with de novo scoliosis between the ages of 40 and 80 years. Most of those patients (32) were females. Thirty-eight were noted to be osteopenic. He concluded from his study that osteoporosis was a significant etiologic factor. This was contradicted by other investigators.5-16 Robin et al,5 in a follow-up random population study, found no direct correlation between osteoporosis and the development of scoliosis; they reported that 394 of 554 patients aged 50-84 years had developed some degree of scoliosis, with equal distribution in men and women. Fifty-five patients had developed a degenerative spinal deformity. There was no relation with the degree of osteoporosis, prior scoliosis, or sex of the patient. The authors concluded that osteoporosis is not a cause of adult scoliosis. In fact, they hypothesized that adult degenerative scoliosis may have an etiology similar to that of adolescent idiopathic scoliosis. In 1987, Thevenon et al16 demonstrated no relationship between the development of scoliosis and decreased vertebral bone mineral density (BMD) in a group of 56 patients aged at least 60 years. They only demonstrated a weak correlation between the development of lumbar scoliosis and low BMD of the femoral neck.16 However these studies likely included patients with adult idiopathic scoliosis and were not all degenerative curves. Degenerative scoliosis may be thought of as asymmetric collapse of the disc and incompetence and hypertrophy of the facet joints, leading to a lateral and rotational deformity. The result is a deformity combined with varying degrees of lateral recess, foraminal and central stenosis. Although not well researched, this model seems to represent well the heterogeneous patient population with this condition. Another theory for the development of de novo scoliosis that has been suggested and I support is that adult scoliosis may be triggered by nerve root irritation, secondary to foraminal or lateral recess stenosis. This causes sciatic or painful scoliosis, which can be initially flexible, but when longstanding, structural deformity may develop and become selfsustainable and continues to progress. This theory is further supported by the well-described sciatic or painful scoliosis, which may result from nerve root compression from a herniated nucleus pulposus. Although the latter usually resolves once the inciting compression is removed, that may not be the case in older individuals with a more degenerative spine.
Natural History of Degenerative Scoliosis Pritchett and Bortel14 studied 200 scoliosis patients: curves ranged from 14°-60° (mean, 24°); 43 had curves ⬎ 35°. Of the 41 patients who had radiographs over at least a 10-year interval, 73% had curves that increased an average of 3°/year. The Cobb angle, lateral-listhesis, degree of apical rotation,
9 and the relation of the intercrest line through the lumbar spine were valuable prognostic factors. When vertebral rotation was at least grade 2 and when the intercrestal line passed through the disc space of L4-5 or below, all curves progressed. All patients who demonstrated progression had either initial curves with a Cobb angle ⱖ30° or a lateral-listhesis ⱖ6 mm. Of 41 patients, 27% did not have progressive curves, and all of these patients had an intercrest line that passed through the body of L4. Similar results were reported by Sapkas et al17 in a study of 162 women (mean age, 65 years) at a mean follow-up of 8 years.
Clinical Presentation Patients with degenerative lumbar scoliosis present with complaints ranging from debilitating back and lower extremity pain and spinal imbalance to incidental findings on lumbar radiographs.18 Pritchett and Bortel14 found that, in a group of 200 symptomatic patients, the duration of back pain ranged from 3 to 30 years, and they most often sought medical care for worsening neurogenic claudication or radicular symptoms. One hundred forty-four patients complained of symptoms in one leg and/or foot such as pain and numbness, cramping, burning, tingling, and even weakness. Most symptoms were consistent with spinal stenosis, except that sitting often did not relieve the leg symptoms. Sixty-five patients complained of gait abnormalities, and 12 complained of unexplained urinary incontinence. Physical examination revealed neurologic abnormalities in 91 of the 144 patients with lower extremity symptoms. Most had decreased sensation in the L4 or L5 distribution; 61 patients had atrophy of the calf, and 56 had atrophy of the buttock or thigh. Neither sagittal nor coronal imbalance was a significant problem in any of their patients. Radicular symptoms are often unilateral and more common on the side of the concavity of the deformity. In a series of 12 patients with symptomatic degenerative lumbar scoliosis, pain was unilateral in 8 and bilateral in 4. In only one patient the symptoms were on the convex side; in 3, they were on the concave side.2 Pritchett and Bortel14 performed myelography on 45 patients and showed that compression was typically greatest at the apex of the concavity of the curve. Robin et al5 found little relation between the presence of lateral osteophytes and the concave or convex side of the lumbar spine. The presence of unilateral symptoms, therefore, most likely occurs in the lower extremity on the concave side of the deformity. The presence of bilateral or unilateral symptoms on the convex side of the deformity can be attributed to underlying stenosis within the primary curve or the lower lumbar compensatory curve.18 Coronal or sagittal imbalance may be a late presentation especially in patients with advanced degenerative lumbar scoliosis. Severe functional loss may result from sagittal imbalance and can aggravate the spinal stenosis symptoms. Loss of a normal waistline and rib impingement accompany sagittal imbalance. Axial low back pain and cosmetic deformity result from coronal and sagittal plane deformities.
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Figure 3 AP view of the L-spine showing an upper and a lower lumbar curve.
In a patient with degenerative scoliosis whose only symptom is back pain, establishing that the deformity is the cause of the nonradicular back pain may be difficult. Although there are certainly pain patterns typical of idiopathic scoliosis (ie, pain secondary to degeneration at the apex of the curve), it can be more difficult to ascribe pain patterns to specific segmental levels in patients with degenerative scoliosis because the degenerative changes usually are multisegmental. Pain can present in the midlumbar spine or in the paraspinal region on either the concave or the convex side of the deformity, or it may predominate in the lower back.19 In degenerative lumbar scoliosis, the pain patterns may differ from those of idiopathic scoliosis. Grubb et al20 reported on a series of 25 patients with degenerative-onset scoliosis: 84% had symptoms of spinal stenosis only and 16% had both spinal stenosis and axial symptoms. However, of the 28 patients with idiopathic curves, 7.1% had symptoms of spinal stenosis only, 85.3% had mechanical symptoms only, and 7% had both.
K. Kebaish plaint. This is also an opportunity to determine whether the patient is healthy enough to tolerate surgical intervention. Comorbidities, such as osteoporosis, diabetes, cardiac and pulmonary disease, should be identified as well as other potential causes of back pain, such as vascular insufficiency or malignancy. Family history, parents and siblings’ longevity, may affect treatment decisions. Patients’ lifestyle and activity level prior to the onset of symptoms are also very important factors. Physical examination of a patient with degenerative scoliosis may be unremarkable. The lumbar curve is usually less obvious, partly because of the associated lumbar lordosis and also the nature of the soft-tissue structures in this area, unlike thoracic idiopathic curves, which are usually more noticeable. Spinal balance in the sagittal and coronal plane is usually well maintained; loss of lumbar lordosis without sagittal imbalance is typical early on. When sagittal and coronal imbalance are present, they should be noted. Leg length discrepancies, rib impingement, lumbar flexibility, and overall spinal alignment in the sagittal and coronal planes should be identified. In addition, gait should be assessed for compensation or associated neurologic impairment. Range of motion of the hips and knees should be assessed for flexion contractures, which may be contributing to the sagittal imbalance or even occur as a result of longstanding compensation. Height should be measured serially to determine any height loss. Motor function is usually normal. Hyperactive reflexes may indicate superimposed cervical spinal stenosis with upper motor neuron dysfunction, which is important to recognize. Grubb and Lipscomb8 reported leg and/or buttock complaints in 90% of the patients in their study of idiopathic and degenerative scoliosis; only 10% of subjects had positive nerve tension signs.
Clinical Assessment A detailed history should establish the predominant complaint, whether back pain, neurogenic claudication, deformity, or imbalance, and then explore specifics of the com-
Figure 4 Axial CT image at L3-4 in a patient with degenerative scoliosis, showing a myelographic defect within the primary curve secondary to lateral-lithesis and facet joint hypertrophy.
De novo scoliosis
Imaging Studies Imaging studies, including plain radiographs, computed tomographic (CT) myelography, magnetic resonance imaging (MRI), and BMD assessment, are useful in the diagnosis and evaluation of degenerative lumbar scoliosis.
Radiographs Plain radiographs should be obtained with the patient standing without bending at the knees or hips, using long films to assess overall spinal balance in the coronal and sagittal plane. Anteroposterior and lateral radiographs, centered on the lumbar spine, also are useful to assess the details of the deformity, which may be obscured in the long standing scoliosis films. There are usually 2 curves within the involved spinal segments (T11-S1) (Fig. 3); the terminology double lumbar scoliosis can be used here. The curve is greater in the idiopathic group and average 52° (range, 34°-78°). The degenerative group curve average was 28° (range, 15°-53°). However, the average 9° deformity per vertebral level was the same in both groups. An additional finding in the degenerative group was lateral-lithesis, a finding emphasized by Epstein et al.2 MRI can provide further understanding of the local anatomy and identify spinal stenosis. The gantry of the MRI should be aligned coaxial with the deformity to provide more useful information.
Myelography and Postmyelographic CT Myelographic defects are most commonly seen within the compensatory lumbosacral curve in idiopathic scoliosis. In comparison, in degenerative scoliosis most myelographic defects are within the primary curve21 (Fig. 4).
Bone Mineral Density Testing Many authors have studied BMD in relation to patients with degenerative scoliosis.8,16,20,22 Osteoporosis complicates treatment decisions and likely affects outcomes. Dual-energy Xray absorptiometry should be considered in obtained osteoporosis in patients with degenerative lumbar scoliosis, particularly when surgery with spinal instrumentation is considered. The proximal femur and distal radius should be obtained because BMD measurement of the spine is unreliable in patients with degenerative scoliosis.
11 patterns were reproduced in 66% of the patients. However the authors concluded that the discographic findings were similar to those of control patients with spinal stenosis and were not evidence of degenerative scoliosis. The authors suggested that discography was not beneficial in the diagnosis of degenerative scoliosis. I find it beneficial to assess the distal levels, in situations where fusion may be stopped proximal to the sacrum, to ascertain the levels not included in the fusion are not potential pain generators.
Nonsurgical Management Nonsurgical management is often selected empirically, and its efficacy is not well supported in the available literature. Nevertheless, nonsurgical treatment should be attempted, and it may even enhance the results of later surgery.18 Nonoperative management is similar to that for patients who have idiopathic curves presenting in adulthood and consists of nonsteroidal anti-inflammatory medications. Tricyclic antidepressants can help with night pain. Gabapentin may help in decreasing neurogenic pain and is generally well tolerated in the geriatric population. The use of narcotic medications for chronic spinal pain is controversial and has long-term side effects. Exercises should avoid extension. General aerobic conditioning can also be beneficial. Braces and corsets may offer temporary relief, but there are no studies to prove their efficacy over time. Treatment of existent osteoporosis and prevention of further bone loss are encouraged, particularly in the female patients.
Surgical Management Indications The most common indication for surgery in patients with degenerative scoliosis is nerve root symptoms and spinal stenosis. Back pain is a less common indication. The debate about who can be treated by decompression alone and who requires decompression with fusion is not resolved.21 I believe decompression without fusion can only be done when it is limited to one nerve root and the facets can be preserved. If greater decompression is necessary or the facets joints are sacrificed, the surgical procedure should include a fusion of the entire curve with correction of the deformity; otherwise, progression and increasing pain are expected future problems.
Discography The adult-onset scoliosis patients have diffuse degenerate changes within the curve, but concordant pain may not frequently be reproduced by discography. In comparison, reproduction of pain by discography is common in the idiopathic group. It is speculated that when degeneration is so advanced, injection does not distend the disc, and pain does not result.21 Grubb and Lipscomb8 performed discography on 12 of their patients with degenerative scoliosis, all of whom were thought to have mechanical back pain. On discography, all had 3 or more abnormal disks, and in 8 patients, all disks proved to be abnormal radiographically. Pain
Goals of Surgical Treatment The main goals for surgical treatment depend on the clinical presentation as well as the patient’s own expectations. Several main goals need to be achieved; these include decompression of neural structures when radicular or neurogenic symptoms are present, achieving a balanced, stable spine, and maintaining that through a solid fusion when indicated, while minimizing the potential risks for junctional problem both acute and chronic. The presence of signs of instability such as lateral listhesis, spondylolithesis, rotatory subluxation, or a significant curve would necessitate adding a fusion to a decom-
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Figure 5 (A) Standing AP radiographs pre- and postoperatively of a 68-year-old female with degenerative scoliosis treated with posterior instrumented fusion from T10 to sacrum. (B) Standing lateral radiographs of the same patient.
pressive procedure. These goals need to be achieved while minimizing the potential perioperative risks associated with a challenging surgery, in a population with significant health problems.
Preoperative Evaluation General assessment for comorbidities must include cardiac evaluation, especially for patients over age 50. Nutritional assessment is very important, as some patients may need perioperative enteral or even parenteral hyperalimentation. Pulmonary function testing should be considered when there is a history of respiratory compromise and especially in patients with a large thoracic/thoracolumbar curve or if an anterior approach is contemplated. Radiographic evaluation should include long-cassette erect posteroanterior and lateral views, in addition to the routine lumbar radiographs. Flexibility films will help in assessing the correctability of the curves. MRI is usually adequate for assessing the spinal canal and the neural elements; however, I usually prefer CT myelography in patients with large curves and in patients who already have posterior instrumentation in place. In females over age 40 a baseline dual-energy X-ray absorptiometry scan on the hips should also be obtained; this may aid in deciding whether pedicle fixation augmentation or prophylactic vertebroplasty at the junctional levels may be required.
Surgical Approaches It is important to establish whether decompression is necessary, as assessed by the preoperative findings and imaging studies. There is no one criterion to establish that adequate decompression has been accomplished, unless the patient presents with very specific nerve root findings localized to 1 or 2 levels. The criteria considered are the following: the levels of involvement seen by MRI or CT; the restoration of pulsatile dura; and the patency of the foramina. Intraoperative evoked somatosensory potentials have also been reported to be useful.21 Some surgeons often take a radical approach, including removal of facets, pars, and portions of the pedicles to ensure adequate decompression, but I do not feel such a radical approach is necessary. Fusion in these patients should always be instrumented; segmental pedicle screw fixation is the preferred fixation technique. In general, poly-axial pedicle screw systems are most suitable. If extension to S1 is needed, it is crucial to incorporate the pelvis or add 2 additional points of fixation in the sacrum (Fig. 5). Uninstrumented fusion in situ with local bone graft is not adequate and is associated with higher rate of pseudoarthrosis with subsequent progression of the deformity. When fusion is extended to the sacrum, as is often required in these degenerative curves, additional sacral and/or pelvic fixation should be added, when fusing 4 or more levels. Also adding interbody fusion at L5-S1 will decrease the
De novo scoliosis
13 An oblique L5 takeoff and hemisacralization were seen in 25% of patients and were relevant to the decision to include the lumbosacral joint. When all criteria were applied, the same investigators24 reported significant pain improvement in 89% of patients. Lordosis should always be restored. A patient fused in kyphosis is a very unhappy one.
Figure 6 Lateral radiograph showing posterior fusion from T10 to the sacrum with an anterior fusion at L5-S1 through an anterior lumbar interbody fusion using a femoral ring allograft.
incidence of pseudoarthrosis. This can be achieved via a separate anterior approach (Fig. 6) or through a posterior interbody technique such as a transforaminal lumbar interbody fusion, depending on the surgeons experience and preference, and should be individualized for each patient. This perspective is not shared by some. For example, Epstein et al2 thought that patients with significant osteophytes might be treated by decompression alone, a perspective which is also advocated by Nachemson.23 If fusion is to be done, the question is how many vertebrae to include in the fusion. Nash et al24 have analyzed whether the criteria for fusion extent in the adolescent are applicable to the adult. The criteria selected were the stable zone, central sacral line, neutrally rotated vertebra, degenerative changes, rotatory subluxation, and hemisacralization. They concluded that multiple factors needed to be considered in selecting the extent of fusion, and that no single measurement had particular predictive value. The stable zone and the central sacral line were of little use in comparison to the adolescent patient with scoliosis. However, it was relevant when the fusion included L2, L3, and L4. The most important factors were the magnitude of degeneration and its extent into the lower lumbar levels. Incorporation of vertebral levels with rotatory subluxation, disc space narrowing, and wedging is important.
Figure 7 (A) Lateral photo and radiograph of a 62-year-old female was fused to L5 elsewhere and sustained an L5 fracture soon after her surgery elsewhere leading to severe sagittal imbalance. (B) Postoperative photo and radiograph showing correction using an L5 osteotomy with extension of fusion to the sacrum and good correction of her sagittal balance. (Color version of figure is available online.)
K. Kebaish
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Fusion Levels The same principles followed for adult idiopathic scoliosis should be followed here. However for degenerative scoliotics, it is not usually possible to stop caudally at L3 or L4, as most of these curves occur at those levels. Often times it is necessary to go down to the sacrum. As in idiopathic adult scoliosis, it is important to begin and end the fusion at neutral and stable vertebrae.15 Ending the fusion next to a rotary subluxation will accelerate the development of junctional deformities. The apex of thoracic kyphosis should always be avoided as the proximal extent of the fusion. Long-cassette standing radiographs will aid in establishing the coronal and sagittal gravity lines and also accurately identify the stable and neutral vertebrae.
Fusion to the Sacrum There is controversy regarding whether to fuse to the sacrum in a patient with degenerative lumbar scoliosis. Although some reports claim a higher complication rate and lower satisfaction in patients fused to the sacrum,22,25,26 recent studies show the opposite.27 Fusion to the sacrum should always be considered in the following situations: (1) a fixed unbalanced lumbosacral curve; (2) significant sagittal imbalance or flat back deformity; (3) patients who had or require a laminectomy at the lumbosacral junction; (4) osteoporotic patients; (5) substantial disc degeneration of L4-5 and L5-S1. I have had several distal fixation failures and fractures when long fusions are stopped at the L4 or L5 vertebra in osteoporotic individual, even when L4 or L5 vertebrae were both stable and neutral. Extending the fusion to the sacrum will allow for more fixation points into the S1 pedicle with additional sacral and/or pelvic fixation. In this situation, I almost always add interbody fusion at L5-S1. My threshold for extending the fusion to the sacrum has become lower over the last few years, given the difficulty and high complication rates when revision surgery is required, especially in the patient who develops significant sagittal imbalance as a result an acute fracture or distal fixation failure (Fig. 7).
Surgical Results and Complications Simmons et al28 reported on spinal stenosis associated with scoliosis. In a review of 40 patients, all treated by posterior decompression, pedicle screw fixation with an average age of 61.5 years, marked improvement in pain was noted in 93%. The average degree of deformity preoperatively was 37° and postoperatively 19°. There were no associated deaths, instrumentation failures, or pseudoarthroses. Marchesi and Aebi29 also reported on the use of pedicle fixation in the treatment of degenerative adult lumbar scoliosis. The average correction was just over 50%. Satisfactory results were obtained in 86%. Pseudoarthrosis occurred in 4%. Mean age was 60 years. Grubb et al9 in a series of 53 adult scoliotics including idiopathic and degenerative cases noted an 80% reduction in pain among idiopathic scoliotics and 70% reduction in degenerative patients. Pseudoarthrosis rate was 4% among id-
iopathic adult scoliotics and 33% among degenerative scoliotics. All pseudoarthroses were in patients fused to the sacrum with posterior procedures alone.
Summary and Conclusion De novo or degenerative scoliosis is used to describe coronal deformities in adult patients who have no history of scoliosis as adolescents; it is often progressive in nature and is associated with degenerative changes in the spinal column. De novo scoliosis rarely presents before 40 years of age. When surgical treatment is indicated, careful preoperative evaluation surgical planning should always be done. There are increased risks of complications in this population compared to adolescent scoliosis. The deformities are often more rigid; extensive posterior release in addition to solid pedicle fixation and supplemental pelvic fixation in fusion to the sacrum will allow the surgeon to address most of these deformities through a posterior approach. Anterior approach may be reserved to add structural support to the lumbosacral junction. Chronologic age of the patients with degenerative scoliosis is not a contraindication to surgery. Restoration of lumbar lordosis is paramount and use of pedicle fixation in osteoporotic bone will allow adequate balance to be achieved. Despite the high risk of complications in patients undergoing reconstructive surgery for de novo scoliosis, most studies suggest a significant improvement in quality of life and a high rate of patient satisfaction. However appropriate patients selection and understanding patient expectations are crucial in achieving a successful outcome.
References 1. Simmons EH, Capicotto WN: Posterior transpedicular Zielke instrumentation of the lumbar spine. Clin Orthop Relat Res 236:180, 1989 2. Epstein JA, Epstein BS, Jones MD: Symptomatic lumbar scoliosis with degenerative changes in the elderly. Spine 4:542-547, 1979 3. Vanderpool DW, James JIP, Wynne-Davies R: Scoliosis in the elderly. J Bone Joint Surg Am 51:446-455, 1969 4. Kebaish KM, Voros G, Neubauer P, et al: Prevalence of scoliosis in adults age 40 years and older: a study of 2973 individuals. Presented at the North American Spine Society 22nd Annual Meeting, Austin, Texas, October 2007 5. Robin GC, Span Y, Steinberg R, et al: Scoliosis in the elderly: A follow-up study. Spine 7:355-359, 1982 6. Benner B, Ehni G: Degenerative lumbar scoliosis. Spine 4:548, 1979 7. Grubb SA, Lipscomb HJ, Coonrad RW: Degenerative adult onset scoliosis. Spine 13:241-245, 1988 8. Grubb SA, Lipscomb HJ: Diagnostic findings in painful adult scoliosis. Spine 17:518-527, 1992 9. Grubb SA, Lipscomb HI, Sub PB: Results of surgical treatment of painful adult scoliosis. Presented at the Annual Meeting of the Scoliosis Research Society, Dublin, 1993 10. Perennou U, Marcelli C, Harrison C, et al: Adult lumbar scoliosis: Epidemiologic aspects in a low-hack-pain population. Spine 19:123, 1994 11. Nilsonne U, Lundgren KU: Long-term prognosis in idiopathic scoliosis. Acta Orthop Scand 39:456-465, 1968 12. Farfan HF, Huberdeau RM, Dubow HI: Lumbar intervertebral disc degeneration: The influence of geometrical features on the pattern of disc degeneration. A post mortem study. J Bone Joint Surg Am 54:492510, 1972
De novo scoliosis 13. Kirkaldy-Willis WH, Farfan HF: Instability of the lumbar spine. Clin Orthop Relat Res 165:110-123, 1982 14. Pritchett JW, Bortel DT: Degenerative symptomatic lumbar scoliosis. Spine 18:700-703, 1993 15. Bridwell KH: Degenerative scoliosis, in Bridwell KH, DeWald RL (eds): The Textbook of Spinal Surgery. Chapter 48 (ed 2). Philadelphia, PA, Lippincott-Raven, 1977, pp 733-775 16. Thevenon A, Pollez B, Cantegrit F, et al: Relationship between kyphosis, scoliosis, and osteoporosis in the elderly population. Spine 12:744745, 1987 17. Sapkas G, Efstathiou P, Badekas AT, et al: Radiological parameters associated with the evolution of degenerative scoliosis. Bull Hosp Joint Dis 55:40-45, 1996 18. Tribus CB: Degenerative lumbar scoliosis: evaluation and management. J Am Acad Orthop Surg 11(3):174-183, 2003 19. Winter RB, Lonstein JE, Denis F: Pain patterns in adult scoliosis. Orthop Clin North Am 19:339-345, 1988 20. Grubb SA, Lipscomb HJ, Sub PB: Results of surgical treatment of painful adult scoliosis. Spine 19:1619-1627, 1994 21. Kostuik JP: Adult scoliosis: the lumbar spine, in Bridwell KH, DeWald RL (eds): The Textbook of Spinal Surgery. Chapter 47 (ed 2). Philadelphia, PA, Lippincott-Raven, 1977, pp 733-775
15 22. Grubb SA, Lipscomb HJ, Guilford WB: The relative value of lumbar roentgenograms, Metrizamide myelography, and discography in the assessment of patients with chronic low-back syndrome. Spine 12:282286, 1987 23. Nachemson A: A long-term follow-up study of nontreated scoliosis. J Bone Joint Surg Am 50:203, 1969 24. Nash CL, Goldstein JM, Wilham MR: Selection of lumbar fusion levels in adult idiopathic scoliosis patients. Presented at the Annual Meeting of the Scoliosis Research Society, Amsterdam, 1989 25. Eck KR, Bridwell KH, Ungacta FF, et al: Complications and results of long adult deformity fusions down to L4, L5, and the sacrum. Spine 26:E182-E192, 2001 26. Emami A, Deviren V, Berven S, et al: Outcome and complications of long fusions to the sacrum in adult spine deformity: Luque–Galveston, combined iliac and sacral screws, and sacral fixation. Spine 27:776786, 2002 27. Kuklo TR, Bridwell KH, Lewis SJ, et al: Minimum 2-year analysis of sacropelvic fixation and L5-S1 fusion using S1 and iliac screws. Spine 26:1976-1983, 2001 28. Simmons ED Jr, Simmons EN: Spinal stenosis with scoliosis. Spine 17:S172-175, 1992 29. Marchesi DO, Aebi M: Pedicle fixation devices in the treatment of adult lumbar scoliosis. Spine 17:5304, 1992
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e novo scoliosis is a term used in adult patients who have no history of scoliosis as adolescents but then develop a coronal plane deformity that may be of a progressive nature and is associated with degenerative changes in the spinal column. Degenerative scoliosis rarely presents before 40 years of age. It has been referred to as “collapsing scoliosis,”1 “de novo adult scoliosis,” and “senescent lumbar scoliosis.”2 How often this occurs is unknown. Differentiation from degenerative idiopathic scoliosis may be difficult. The coronal curve usually involves the lumbar and less commonly the thoracolumbar junction. The lumbar curve is often a dual curve with a larger one in the proximal lumbar spine, with the apex at L2 or L3. It rarely exceeds 60°. Degenerative changes always affect the facet joints and the intervertebral discs and the curves are commonly associated with loss of lumbar lordosis (Fig. 1). Department of Orthopaedic Surgery, Johns Hopkins University, Johns Hopkins Outpatient Center, Baltimore, MD. Address reprint requests to Khaled Kebaish, MD, Department of Orthopaedic Surgery, Johns Hopkins University, Johns Hopkins Outpatient Center, 601 N. Caroline Street, Suite 5243, Baltimore, MD 21287-0882. E-mail: [email protected]
1040-7383/09/$-see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1053/j.semss.2008.11.002
The only certain proof that a patient has a new curve, rather than a progression in a previously unrecognized curve (Fig. 2), is a normal spinal radiograph sometime at a younger age. Therefore, an accurate estimate of the prevalence in the population is not possible to determine. Vanderpool et al3 were among the first to study this problem carefully. Their control group, which averaged 61.4 years of age, had a prevalence of 6%, but most curves were small (7°-16°). A similar finding was observed in adult relatives of patients with scoliosis. An osteoporotic group showed 36% with curvature. The average age was 71 years. They were able to identify 14 of the 36 patients who had unequivocal evidence of having been free of scoliosis at an earlier age. The average age of onset was 40 years. An episode of back pain was usually the identified point at which scoliosis began. The curves were, in general, mild and ranged from 7° to 53°. They found that the distribution of involvement in all levels of the spine was equal. A similar finding was present in 24 patients with osteomalacia; 38% had a curvature, but it was generally mild, and had little or no rotation. Because of this analysis, they concluded that adult-onset curves were secondary to osteomalacia and osteoporosis. However a recent study showed no correlation between osteoporosis and the prevalence of scoliosis.4 7
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Figure 1 AP and lateral radiographs of a 67-year-old lady with de novo scoliosis showing loss of lumbar lordosis.
A different perspective was proposed by Robin et al.5 They followed a group of 554 subjects for intervals of 8-13 years. Some degree of scoliosis was found in 70% of subjects, and 30% had curves of greater than 10°. Ten percent of their patients developed scoliosis in the follow-up interval. However, they concluded that there was little relationship to progression, osteoporosis, or degenerative changes in the spine. Their conclusion was interesting: “Since scoliosis in the elderly seldom becomes a clinical problem of significance, there would appear to be no valid reason for more extensive study of this condition at this time.” Their conclusion is striking in its contrast to the experience of Epstein et al,2 Benner and Ehni,6 Grubb,7-9 and Perennou et al10: that scoliosis occurs de novo in adults, is probably degenerative in etiology, and can be the source of significant symptoms. Attempts to differentiate the adults with pre-existent but progressing scoliosis from those with a new curve have been made by Grubb.7-9 Significant differences and similarities were identified.11 All of the idiopathic group were females with a mean age of 42; however, the sex distribution was equal in the degenerative group, and the mean age was older at 60 years. Low back pain incidence was in both groups, radiating into the buttock and upper thighs. Although 90% of subjects with degenerative curves had symptoms suggestive of spinal stenosis, only 31% of the idiopathic group had such pain.
Etiology Osteoporosis, degenerative disc disease, osteoarthritis, compression fractures, spinal canal stenosis, endochondral abnormalities, and facet tropism have all been implicated in the development of degenerative scoliosis.12-14 None have been shown to be directly related. In fact, little is known about the etiology of degenerative scoliosis. In 1969, Vanderpool et al3 reported that the incidence of degenerative scoliosis was 36% in patients with osteoporosis
Figure 2 (A) AP lumbar radiograph of a female patient at age 32. (B) Same patient presenting with severe scoliosis at age 64.
De novo scoliosis and 38% in patients with osteomalacia, 6-fold higher than in age- and sex-matched controls. The authors suggested that the higher prevalence of scoliosis in patients over age 50 implicated osteoporosis as the cause of the deformity. Bridwell15 reviewed 48 patients with de novo scoliosis between the ages of 40 and 80 years. Most of those patients (32) were females. Thirty-eight were noted to be osteopenic. He concluded from his study that osteoporosis was a significant etiologic factor. This was contradicted by other investigators.5-16 Robin et al,5 in a follow-up random population study, found no direct correlation between osteoporosis and the development of scoliosis; they reported that 394 of 554 patients aged 50-84 years had developed some degree of scoliosis, with equal distribution in men and women. Fifty-five patients had developed a degenerative spinal deformity. There was no relation with the degree of osteoporosis, prior scoliosis, or sex of the patient. The authors concluded that osteoporosis is not a cause of adult scoliosis. In fact, they hypothesized that adult degenerative scoliosis may have an etiology similar to that of adolescent idiopathic scoliosis. In 1987, Thevenon et al16 demonstrated no relationship between the development of scoliosis and decreased vertebral bone mineral density (BMD) in a group of 56 patients aged at least 60 years. They only demonstrated a weak correlation between the development of lumbar scoliosis and low BMD of the femoral neck.16 However these studies likely included patients with adult idiopathic scoliosis and were not all degenerative curves. Degenerative scoliosis may be thought of as asymmetric collapse of the disc and incompetence and hypertrophy of the facet joints, leading to a lateral and rotational deformity. The result is a deformity combined with varying degrees of lateral recess, foraminal and central stenosis. Although not well researched, this model seems to represent well the heterogeneous patient population with this condition. Another theory for the development of de novo scoliosis that has been suggested and I support is that adult scoliosis may be triggered by nerve root irritation, secondary to foraminal or lateral recess stenosis. This causes sciatic or painful scoliosis, which can be initially flexible, but when longstanding, structural deformity may develop and become selfsustainable and continues to progress. This theory is further supported by the well-described sciatic or painful scoliosis, which may result from nerve root compression from a herniated nucleus pulposus. Although the latter usually resolves once the inciting compression is removed, that may not be the case in older individuals with a more degenerative spine.
Natural History of Degenerative Scoliosis Pritchett and Bortel14 studied 200 scoliosis patients: curves ranged from 14°-60° (mean, 24°); 43 had curves ⬎ 35°. Of the 41 patients who had radiographs over at least a 10-year interval, 73% had curves that increased an average of 3°/year. The Cobb angle, lateral-listhesis, degree of apical rotation,
9 and the relation of the intercrest line through the lumbar spine were valuable prognostic factors. When vertebral rotation was at least grade 2 and when the intercrestal line passed through the disc space of L4-5 or below, all curves progressed. All patients who demonstrated progression had either initial curves with a Cobb angle ⱖ30° or a lateral-listhesis ⱖ6 mm. Of 41 patients, 27% did not have progressive curves, and all of these patients had an intercrest line that passed through the body of L4. Similar results were reported by Sapkas et al17 in a study of 162 women (mean age, 65 years) at a mean follow-up of 8 years.
Clinical Presentation Patients with degenerative lumbar scoliosis present with complaints ranging from debilitating back and lower extremity pain and spinal imbalance to incidental findings on lumbar radiographs.18 Pritchett and Bortel14 found that, in a group of 200 symptomatic patients, the duration of back pain ranged from 3 to 30 years, and they most often sought medical care for worsening neurogenic claudication or radicular symptoms. One hundred forty-four patients complained of symptoms in one leg and/or foot such as pain and numbness, cramping, burning, tingling, and even weakness. Most symptoms were consistent with spinal stenosis, except that sitting often did not relieve the leg symptoms. Sixty-five patients complained of gait abnormalities, and 12 complained of unexplained urinary incontinence. Physical examination revealed neurologic abnormalities in 91 of the 144 patients with lower extremity symptoms. Most had decreased sensation in the L4 or L5 distribution; 61 patients had atrophy of the calf, and 56 had atrophy of the buttock or thigh. Neither sagittal nor coronal imbalance was a significant problem in any of their patients. Radicular symptoms are often unilateral and more common on the side of the concavity of the deformity. In a series of 12 patients with symptomatic degenerative lumbar scoliosis, pain was unilateral in 8 and bilateral in 4. In only one patient the symptoms were on the convex side; in 3, they were on the concave side.2 Pritchett and Bortel14 performed myelography on 45 patients and showed that compression was typically greatest at the apex of the concavity of the curve. Robin et al5 found little relation between the presence of lateral osteophytes and the concave or convex side of the lumbar spine. The presence of unilateral symptoms, therefore, most likely occurs in the lower extremity on the concave side of the deformity. The presence of bilateral or unilateral symptoms on the convex side of the deformity can be attributed to underlying stenosis within the primary curve or the lower lumbar compensatory curve.18 Coronal or sagittal imbalance may be a late presentation especially in patients with advanced degenerative lumbar scoliosis. Severe functional loss may result from sagittal imbalance and can aggravate the spinal stenosis symptoms. Loss of a normal waistline and rib impingement accompany sagittal imbalance. Axial low back pain and cosmetic deformity result from coronal and sagittal plane deformities.
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Figure 3 AP view of the L-spine showing an upper and a lower lumbar curve.
In a patient with degenerative scoliosis whose only symptom is back pain, establishing that the deformity is the cause of the nonradicular back pain may be difficult. Although there are certainly pain patterns typical of idiopathic scoliosis (ie, pain secondary to degeneration at the apex of the curve), it can be more difficult to ascribe pain patterns to specific segmental levels in patients with degenerative scoliosis because the degenerative changes usually are multisegmental. Pain can present in the midlumbar spine or in the paraspinal region on either the concave or the convex side of the deformity, or it may predominate in the lower back.19 In degenerative lumbar scoliosis, the pain patterns may differ from those of idiopathic scoliosis. Grubb et al20 reported on a series of 25 patients with degenerative-onset scoliosis: 84% had symptoms of spinal stenosis only and 16% had both spinal stenosis and axial symptoms. However, of the 28 patients with idiopathic curves, 7.1% had symptoms of spinal stenosis only, 85.3% had mechanical symptoms only, and 7% had both.
K. Kebaish plaint. This is also an opportunity to determine whether the patient is healthy enough to tolerate surgical intervention. Comorbidities, such as osteoporosis, diabetes, cardiac and pulmonary disease, should be identified as well as other potential causes of back pain, such as vascular insufficiency or malignancy. Family history, parents and siblings’ longevity, may affect treatment decisions. Patients’ lifestyle and activity level prior to the onset of symptoms are also very important factors. Physical examination of a patient with degenerative scoliosis may be unremarkable. The lumbar curve is usually less obvious, partly because of the associated lumbar lordosis and also the nature of the soft-tissue structures in this area, unlike thoracic idiopathic curves, which are usually more noticeable. Spinal balance in the sagittal and coronal plane is usually well maintained; loss of lumbar lordosis without sagittal imbalance is typical early on. When sagittal and coronal imbalance are present, they should be noted. Leg length discrepancies, rib impingement, lumbar flexibility, and overall spinal alignment in the sagittal and coronal planes should be identified. In addition, gait should be assessed for compensation or associated neurologic impairment. Range of motion of the hips and knees should be assessed for flexion contractures, which may be contributing to the sagittal imbalance or even occur as a result of longstanding compensation. Height should be measured serially to determine any height loss. Motor function is usually normal. Hyperactive reflexes may indicate superimposed cervical spinal stenosis with upper motor neuron dysfunction, which is important to recognize. Grubb and Lipscomb8 reported leg and/or buttock complaints in 90% of the patients in their study of idiopathic and degenerative scoliosis; only 10% of subjects had positive nerve tension signs.
Clinical Assessment A detailed history should establish the predominant complaint, whether back pain, neurogenic claudication, deformity, or imbalance, and then explore specifics of the com-
Figure 4 Axial CT image at L3-4 in a patient with degenerative scoliosis, showing a myelographic defect within the primary curve secondary to lateral-lithesis and facet joint hypertrophy.
De novo scoliosis
Imaging Studies Imaging studies, including plain radiographs, computed tomographic (CT) myelography, magnetic resonance imaging (MRI), and BMD assessment, are useful in the diagnosis and evaluation of degenerative lumbar scoliosis.
Radiographs Plain radiographs should be obtained with the patient standing without bending at the knees or hips, using long films to assess overall spinal balance in the coronal and sagittal plane. Anteroposterior and lateral radiographs, centered on the lumbar spine, also are useful to assess the details of the deformity, which may be obscured in the long standing scoliosis films. There are usually 2 curves within the involved spinal segments (T11-S1) (Fig. 3); the terminology double lumbar scoliosis can be used here. The curve is greater in the idiopathic group and average 52° (range, 34°-78°). The degenerative group curve average was 28° (range, 15°-53°). However, the average 9° deformity per vertebral level was the same in both groups. An additional finding in the degenerative group was lateral-lithesis, a finding emphasized by Epstein et al.2 MRI can provide further understanding of the local anatomy and identify spinal stenosis. The gantry of the MRI should be aligned coaxial with the deformity to provide more useful information.
Myelography and Postmyelographic CT Myelographic defects are most commonly seen within the compensatory lumbosacral curve in idiopathic scoliosis. In comparison, in degenerative scoliosis most myelographic defects are within the primary curve21 (Fig. 4).
Bone Mineral Density Testing Many authors have studied BMD in relation to patients with degenerative scoliosis.8,16,20,22 Osteoporosis complicates treatment decisions and likely affects outcomes. Dual-energy Xray absorptiometry should be considered in obtained osteoporosis in patients with degenerative lumbar scoliosis, particularly when surgery with spinal instrumentation is considered. The proximal femur and distal radius should be obtained because BMD measurement of the spine is unreliable in patients with degenerative scoliosis.
11 patterns were reproduced in 66% of the patients. However the authors concluded that the discographic findings were similar to those of control patients with spinal stenosis and were not evidence of degenerative scoliosis. The authors suggested that discography was not beneficial in the diagnosis of degenerative scoliosis. I find it beneficial to assess the distal levels, in situations where fusion may be stopped proximal to the sacrum, to ascertain the levels not included in the fusion are not potential pain generators.
Nonsurgical Management Nonsurgical management is often selected empirically, and its efficacy is not well supported in the available literature. Nevertheless, nonsurgical treatment should be attempted, and it may even enhance the results of later surgery.18 Nonoperative management is similar to that for patients who have idiopathic curves presenting in adulthood and consists of nonsteroidal anti-inflammatory medications. Tricyclic antidepressants can help with night pain. Gabapentin may help in decreasing neurogenic pain and is generally well tolerated in the geriatric population. The use of narcotic medications for chronic spinal pain is controversial and has long-term side effects. Exercises should avoid extension. General aerobic conditioning can also be beneficial. Braces and corsets may offer temporary relief, but there are no studies to prove their efficacy over time. Treatment of existent osteoporosis and prevention of further bone loss are encouraged, particularly in the female patients.
Surgical Management Indications The most common indication for surgery in patients with degenerative scoliosis is nerve root symptoms and spinal stenosis. Back pain is a less common indication. The debate about who can be treated by decompression alone and who requires decompression with fusion is not resolved.21 I believe decompression without fusion can only be done when it is limited to one nerve root and the facets can be preserved. If greater decompression is necessary or the facets joints are sacrificed, the surgical procedure should include a fusion of the entire curve with correction of the deformity; otherwise, progression and increasing pain are expected future problems.
Discography The adult-onset scoliosis patients have diffuse degenerate changes within the curve, but concordant pain may not frequently be reproduced by discography. In comparison, reproduction of pain by discography is common in the idiopathic group. It is speculated that when degeneration is so advanced, injection does not distend the disc, and pain does not result.21 Grubb and Lipscomb8 performed discography on 12 of their patients with degenerative scoliosis, all of whom were thought to have mechanical back pain. On discography, all had 3 or more abnormal disks, and in 8 patients, all disks proved to be abnormal radiographically. Pain
Goals of Surgical Treatment The main goals for surgical treatment depend on the clinical presentation as well as the patient’s own expectations. Several main goals need to be achieved; these include decompression of neural structures when radicular or neurogenic symptoms are present, achieving a balanced, stable spine, and maintaining that through a solid fusion when indicated, while minimizing the potential risks for junctional problem both acute and chronic. The presence of signs of instability such as lateral listhesis, spondylolithesis, rotatory subluxation, or a significant curve would necessitate adding a fusion to a decom-
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Figure 5 (A) Standing AP radiographs pre- and postoperatively of a 68-year-old female with degenerative scoliosis treated with posterior instrumented fusion from T10 to sacrum. (B) Standing lateral radiographs of the same patient.
pressive procedure. These goals need to be achieved while minimizing the potential perioperative risks associated with a challenging surgery, in a population with significant health problems.
Preoperative Evaluation General assessment for comorbidities must include cardiac evaluation, especially for patients over age 50. Nutritional assessment is very important, as some patients may need perioperative enteral or even parenteral hyperalimentation. Pulmonary function testing should be considered when there is a history of respiratory compromise and especially in patients with a large thoracic/thoracolumbar curve or if an anterior approach is contemplated. Radiographic evaluation should include long-cassette erect posteroanterior and lateral views, in addition to the routine lumbar radiographs. Flexibility films will help in assessing the correctability of the curves. MRI is usually adequate for assessing the spinal canal and the neural elements; however, I usually prefer CT myelography in patients with large curves and in patients who already have posterior instrumentation in place. In females over age 40 a baseline dual-energy X-ray absorptiometry scan on the hips should also be obtained; this may aid in deciding whether pedicle fixation augmentation or prophylactic vertebroplasty at the junctional levels may be required.
Surgical Approaches It is important to establish whether decompression is necessary, as assessed by the preoperative findings and imaging studies. There is no one criterion to establish that adequate decompression has been accomplished, unless the patient presents with very specific nerve root findings localized to 1 or 2 levels. The criteria considered are the following: the levels of involvement seen by MRI or CT; the restoration of pulsatile dura; and the patency of the foramina. Intraoperative evoked somatosensory potentials have also been reported to be useful.21 Some surgeons often take a radical approach, including removal of facets, pars, and portions of the pedicles to ensure adequate decompression, but I do not feel such a radical approach is necessary. Fusion in these patients should always be instrumented; segmental pedicle screw fixation is the preferred fixation technique. In general, poly-axial pedicle screw systems are most suitable. If extension to S1 is needed, it is crucial to incorporate the pelvis or add 2 additional points of fixation in the sacrum (Fig. 5). Uninstrumented fusion in situ with local bone graft is not adequate and is associated with higher rate of pseudoarthrosis with subsequent progression of the deformity. When fusion is extended to the sacrum, as is often required in these degenerative curves, additional sacral and/or pelvic fixation should be added, when fusing 4 or more levels. Also adding interbody fusion at L5-S1 will decrease the
De novo scoliosis
13 An oblique L5 takeoff and hemisacralization were seen in 25% of patients and were relevant to the decision to include the lumbosacral joint. When all criteria were applied, the same investigators24 reported significant pain improvement in 89% of patients. Lordosis should always be restored. A patient fused in kyphosis is a very unhappy one.
Figure 6 Lateral radiograph showing posterior fusion from T10 to the sacrum with an anterior fusion at L5-S1 through an anterior lumbar interbody fusion using a femoral ring allograft.
incidence of pseudoarthrosis. This can be achieved via a separate anterior approach (Fig. 6) or through a posterior interbody technique such as a transforaminal lumbar interbody fusion, depending on the surgeons experience and preference, and should be individualized for each patient. This perspective is not shared by some. For example, Epstein et al2 thought that patients with significant osteophytes might be treated by decompression alone, a perspective which is also advocated by Nachemson.23 If fusion is to be done, the question is how many vertebrae to include in the fusion. Nash et al24 have analyzed whether the criteria for fusion extent in the adolescent are applicable to the adult. The criteria selected were the stable zone, central sacral line, neutrally rotated vertebra, degenerative changes, rotatory subluxation, and hemisacralization. They concluded that multiple factors needed to be considered in selecting the extent of fusion, and that no single measurement had particular predictive value. The stable zone and the central sacral line were of little use in comparison to the adolescent patient with scoliosis. However, it was relevant when the fusion included L2, L3, and L4. The most important factors were the magnitude of degeneration and its extent into the lower lumbar levels. Incorporation of vertebral levels with rotatory subluxation, disc space narrowing, and wedging is important.
Figure 7 (A) Lateral photo and radiograph of a 62-year-old female was fused to L5 elsewhere and sustained an L5 fracture soon after her surgery elsewhere leading to severe sagittal imbalance. (B) Postoperative photo and radiograph showing correction using an L5 osteotomy with extension of fusion to the sacrum and good correction of her sagittal balance. (Color version of figure is available online.)
K. Kebaish
14
Fusion Levels The same principles followed for adult idiopathic scoliosis should be followed here. However for degenerative scoliotics, it is not usually possible to stop caudally at L3 or L4, as most of these curves occur at those levels. Often times it is necessary to go down to the sacrum. As in idiopathic adult scoliosis, it is important to begin and end the fusion at neutral and stable vertebrae.15 Ending the fusion next to a rotary subluxation will accelerate the development of junctional deformities. The apex of thoracic kyphosis should always be avoided as the proximal extent of the fusion. Long-cassette standing radiographs will aid in establishing the coronal and sagittal gravity lines and also accurately identify the stable and neutral vertebrae.
Fusion to the Sacrum There is controversy regarding whether to fuse to the sacrum in a patient with degenerative lumbar scoliosis. Although some reports claim a higher complication rate and lower satisfaction in patients fused to the sacrum,22,25,26 recent studies show the opposite.27 Fusion to the sacrum should always be considered in the following situations: (1) a fixed unbalanced lumbosacral curve; (2) significant sagittal imbalance or flat back deformity; (3) patients who had or require a laminectomy at the lumbosacral junction; (4) osteoporotic patients; (5) substantial disc degeneration of L4-5 and L5-S1. I have had several distal fixation failures and fractures when long fusions are stopped at the L4 or L5 vertebra in osteoporotic individual, even when L4 or L5 vertebrae were both stable and neutral. Extending the fusion to the sacrum will allow for more fixation points into the S1 pedicle with additional sacral and/or pelvic fixation. In this situation, I almost always add interbody fusion at L5-S1. My threshold for extending the fusion to the sacrum has become lower over the last few years, given the difficulty and high complication rates when revision surgery is required, especially in the patient who develops significant sagittal imbalance as a result an acute fracture or distal fixation failure (Fig. 7).
Surgical Results and Complications Simmons et al28 reported on spinal stenosis associated with scoliosis. In a review of 40 patients, all treated by posterior decompression, pedicle screw fixation with an average age of 61.5 years, marked improvement in pain was noted in 93%. The average degree of deformity preoperatively was 37° and postoperatively 19°. There were no associated deaths, instrumentation failures, or pseudoarthroses. Marchesi and Aebi29 also reported on the use of pedicle fixation in the treatment of degenerative adult lumbar scoliosis. The average correction was just over 50%. Satisfactory results were obtained in 86%. Pseudoarthrosis occurred in 4%. Mean age was 60 years. Grubb et al9 in a series of 53 adult scoliotics including idiopathic and degenerative cases noted an 80% reduction in pain among idiopathic scoliotics and 70% reduction in degenerative patients. Pseudoarthrosis rate was 4% among id-
iopathic adult scoliotics and 33% among degenerative scoliotics. All pseudoarthroses were in patients fused to the sacrum with posterior procedures alone.
Summary and Conclusion De novo or degenerative scoliosis is used to describe coronal deformities in adult patients who have no history of scoliosis as adolescents; it is often progressive in nature and is associated with degenerative changes in the spinal column. De novo scoliosis rarely presents before 40 years of age. When surgical treatment is indicated, careful preoperative evaluation surgical planning should always be done. There are increased risks of complications in this population compared to adolescent scoliosis. The deformities are often more rigid; extensive posterior release in addition to solid pedicle fixation and supplemental pelvic fixation in fusion to the sacrum will allow the surgeon to address most of these deformities through a posterior approach. Anterior approach may be reserved to add structural support to the lumbosacral junction. Chronologic age of the patients with degenerative scoliosis is not a contraindication to surgery. Restoration of lumbar lordosis is paramount and use of pedicle fixation in osteoporotic bone will allow adequate balance to be achieved. Despite the high risk of complications in patients undergoing reconstructive surgery for de novo scoliosis, most studies suggest a significant improvement in quality of life and a high rate of patient satisfaction. However appropriate patients selection and understanding patient expectations are crucial in achieving a successful outcome.
References 1. Simmons EH, Capicotto WN: Posterior transpedicular Zielke instrumentation of the lumbar spine. Clin Orthop Relat Res 236:180, 1989 2. Epstein JA, Epstein BS, Jones MD: Symptomatic lumbar scoliosis with degenerative changes in the elderly. Spine 4:542-547, 1979 3. Vanderpool DW, James JIP, Wynne-Davies R: Scoliosis in the elderly. J Bone Joint Surg Am 51:446-455, 1969 4. Kebaish KM, Voros G, Neubauer P, et al: Prevalence of scoliosis in adults age 40 years and older: a study of 2973 individuals. Presented at the North American Spine Society 22nd Annual Meeting, Austin, Texas, October 2007 5. Robin GC, Span Y, Steinberg R, et al: Scoliosis in the elderly: A follow-up study. Spine 7:355-359, 1982 6. Benner B, Ehni G: Degenerative lumbar scoliosis. Spine 4:548, 1979 7. Grubb SA, Lipscomb HJ, Coonrad RW: Degenerative adult onset scoliosis. Spine 13:241-245, 1988 8. Grubb SA, Lipscomb HJ: Diagnostic findings in painful adult scoliosis. Spine 17:518-527, 1992 9. Grubb SA, Lipscomb HI, Sub PB: Results of surgical treatment of painful adult scoliosis. Presented at the Annual Meeting of the Scoliosis Research Society, Dublin, 1993 10. Perennou U, Marcelli C, Harrison C, et al: Adult lumbar scoliosis: Epidemiologic aspects in a low-hack-pain population. Spine 19:123, 1994 11. Nilsonne U, Lundgren KU: Long-term prognosis in idiopathic scoliosis. Acta Orthop Scand 39:456-465, 1968 12. Farfan HF, Huberdeau RM, Dubow HI: Lumbar intervertebral disc degeneration: The influence of geometrical features on the pattern of disc degeneration. A post mortem study. J Bone Joint Surg Am 54:492510, 1972
De novo scoliosis 13. Kirkaldy-Willis WH, Farfan HF: Instability of the lumbar spine. Clin Orthop Relat Res 165:110-123, 1982 14. Pritchett JW, Bortel DT: Degenerative symptomatic lumbar scoliosis. Spine 18:700-703, 1993 15. Bridwell KH: Degenerative scoliosis, in Bridwell KH, DeWald RL (eds): The Textbook of Spinal Surgery. Chapter 48 (ed 2). Philadelphia, PA, Lippincott-Raven, 1977, pp 733-775 16. Thevenon A, Pollez B, Cantegrit F, et al: Relationship between kyphosis, scoliosis, and osteoporosis in the elderly population. Spine 12:744745, 1987 17. Sapkas G, Efstathiou P, Badekas AT, et al: Radiological parameters associated with the evolution of degenerative scoliosis. Bull Hosp Joint Dis 55:40-45, 1996 18. Tribus CB: Degenerative lumbar scoliosis: evaluation and management. J Am Acad Orthop Surg 11(3):174-183, 2003 19. Winter RB, Lonstein JE, Denis F: Pain patterns in adult scoliosis. Orthop Clin North Am 19:339-345, 1988 20. Grubb SA, Lipscomb HJ, Sub PB: Results of surgical treatment of painful adult scoliosis. Spine 19:1619-1627, 1994 21. Kostuik JP: Adult scoliosis: the lumbar spine, in Bridwell KH, DeWald RL (eds): The Textbook of Spinal Surgery. Chapter 47 (ed 2). Philadelphia, PA, Lippincott-Raven, 1977, pp 733-775
15 22. Grubb SA, Lipscomb HJ, Guilford WB: The relative value of lumbar roentgenograms, Metrizamide myelography, and discography in the assessment of patients with chronic low-back syndrome. Spine 12:282286, 1987 23. Nachemson A: A long-term follow-up study of nontreated scoliosis. J Bone Joint Surg Am 50:203, 1969 24. Nash CL, Goldstein JM, Wilham MR: Selection of lumbar fusion levels in adult idiopathic scoliosis patients. Presented at the Annual Meeting of the Scoliosis Research Society, Amsterdam, 1989 25. Eck KR, Bridwell KH, Ungacta FF, et al: Complications and results of long adult deformity fusions down to L4, L5, and the sacrum. Spine 26:E182-E192, 2001 26. Emami A, Deviren V, Berven S, et al: Outcome and complications of long fusions to the sacrum in adult spine deformity: Luque–Galveston, combined iliac and sacral screws, and sacral fixation. Spine 27:776786, 2002 27. Kuklo TR, Bridwell KH, Lewis SJ, et al: Minimum 2-year analysis of sacropelvic fixation and L5-S1 fusion using S1 and iliac screws. Spine 26:1976-1983, 2001 28. Simmons ED Jr, Simmons EN: Spinal stenosis with scoliosis. Spine 17:S172-175, 1992 29. Marchesi DO, Aebi M: Pedicle fixation devices in the treatment of adult lumbar scoliosis. Spine 17:5304, 1992