Degenerative Lumbar Scoliosis

➢ Degenerative lumbar scoliosis is a common condition, with a higher prevalence in older populations, that can lead to substantial pain and disability. ➢ After a course of nonoperative treatment, surgery is indicated to address neurological deficits and/or disability resulting from deformity with or without stenosis. ➢ Surgical intervention may include decompression with or without fusion and can be performed from an anterior, lateral, posterior, or combined approach. ➢ Despite a relatively high prevalence of perioperative complications, the overall long-term outcomes of surgical interventions for degenerative lumbar scoliosis are favorable in well-selected, medically optimized patients. Degenerative lumbar scoliosis is a progressive coronal plane deformity that includes sagittal malalignment and usually occurs in patients older than forty years of age1. This is in contrast to adult idiopathic scoliosis, which is a result of untreated adolescent idiopathic scoliosis and is more commonly seen in the thoracic spine. Degenerative lumbar scoliosis involves fewer segments and less severe curves than adult idiopathic scoliosis; however, both diagnoses can present with similar symptoms of back pain, lower-limb pain, and functional impairment. The prevalence is difficult to determine, possibly because of the diverse patient populations studied; it has ranged from 1% to 68% in the literature1–8-8, but most studies have demonstrated prevalences of about 7.5% to 15%6. There are radiographic findings that may predict which patients will develop scoliosis (defined as a coronal Cobb angle of >10°), as one community cohort demonstrated that asymmetric disc degeneration and unilateral osteophyte formation led to an increased prevalence of scoliosis5,9. The pathogenesis of degenerative lumbar scoliosis is unknown. However, recently researchers have investigated markers that could help establish an etiology or risk for progression of this condition10. Biomarkers that signify type-II-collagen synthesis and degradation have been studied in patients with osteoarthritis, and similar findings may be seen in patients with degenerative lumbar scoliosis. Compared with controls, patients with degenerative lumbar scoliosis were found to have higher serum levels of keratan sulfate, procollagen type-II C-propeptide (CPII), and collagen-type-II cleavage, with positive correlations between the Cobb angle and the CPII level11, suggesting an increased turnover of the components of the nucleus pulposus and facet joint cartilage in patients with degenerative lumbar scoliosis. Certain N-methyl-D-aspartate (NMDA) receptor genes have also been associated with degenerative lumbar scoliosis12. Although no definitive conclusions can be drawn from these findings at this time, this promising research may establish the etiology or risk for progression of degenerative lumbar scoliosis as well as possible areas for therapeutics. There are conflicting data in the literature regarding the association between osteoporosis and scoliosis. Patients with scoliosis have lower hip bone mineral density than nonscoliotic patients13; however, bone mineral density may not necessarily be an independent predictor of curve magnitude8. Age and ethnicity may also predict the prevalence of degenerative lumbar scoliosis. In a retrospective review of 2973 dual x-ray absorptiometry (DXA) scans, the prevalence of scoliosis was highest in white subjects (11.11% versus 6.49% for black subjects and 4.04% for other races grouped together)4. In the same study, the prevalence increased with age with no difference based on sex4. In a Chinese Han population, the prevalence of scoliosis was even higher than that reported for white subjects (13.3% for those older than forty years), with female sex, age, and osteopenia correlating with the prevalence of degenerative lumbar scoliosis14. A lower body mass index has also been found to be an independent risk factor for scoliosis8. Anatomy The progression of degenerative lumbar scoliosis may be accompanied by structural changes in the local anatomy. The psoas and paravertebral muscles may hypertrophy on the convex side of the curve and degenerate on the concave side of the curve in patients with degenerative lumbar scoliosis15–17-17. Pedicle morphology is also likely to be altered in patients with degenerative lumbar scoliosis, with narrower diameters on the concave side18, and it is important to be aware of this during surgical planning. There are anatomic changes in the foramina of patients with degenerative lumbar scoliosis as well. The foraminal height, interval between the pedicle and superior articular process, and foraminal area are smaller in patients with degenerative lumbar scoliosis compared with controls. These measurements are also smaller on the concave side of the curves19. Certain levels of lumbar nerve roots may be more affected depending on the pattern of curvature. L3 and L4 are more likely to be compressed in the foramen on the concave side of the curve, and the lower roots (L5 and S1) are more likely to be affected on the convex side by lateral recess stenosis18,20. Classification A radiographic classification system for adult scoliosis based on lumbar lordosis and obliquity of the end plate of L3 in the frontal plane was developed by Schwab et al.21. It was modified to include pelvic and sagittal parameters as well as the thoracic curves22 (Table I). This classification has good to excellent intraobserver and interobserver reliability22,23 and has been validated with parameters based on health-related quality-of-life outcome scores. Curves are classified according to the location of the major coronal curve (>30°)—i.e., thoracic only (apical level at T9 or cephalad), lumbar or thoracolumbar (apical level at T10 or caudal), double curve, or type N (no curve of >30°). Sagittal modifiers are based on three parameters: pelvic incidence minus lumbar lordosis, sagittal vertical axis, and pelvic tilt (Table I). These spinopelvic parameters have been found to be important predictors of patient outcomes24. TABLE I - Scoliosis Research Society-Schwab Adult Spinal Deformity Classification* Designation Description Coronal curve type T Thoracic only (lumbar curve <30°) L Thoracolumbar or lumbar only (thoracic curve <30°) D Double curve (thoracic and thoracolumbar curves >30°) N No major coronal deformity (all coronal curves <30°) Sagittal modifier Pelvic incidence minus lumbar lordosis 0 <10° + Moderate (10°-20°) ++ Marked (>20°) Global alignment (sagittal vertical axis) 0 <4 cm + 4-9.5 cm ++ >9.5 cm Pelvic tilt 0 <20° + 20°-30° ++ >30° *Reproduced, with modification, from: Schwab F, Ungar B, Blondel B, Buchowski J, Coe J, Deinlein D, DeWald C, Mehdian H, Shaffrey C, Tribus C, Lafage V. Scoliosis Research Society−Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976). 2012 May 20;37(12):1077-82. Reproduced with permission. Clinical Presentation Patients with degenerative lumbar scoliosis typically present with low back pain and difficulty maintaining an upright posture, with variable degrees of lower-limb pain. The pain typically becomes worse after standing for a long period of time and with fatigue and is relieved by lying down. Symptoms due to neurogenic claudication are variable depending on the concavity or convexity of the curve and the curve level. A thorough neurological examination as well as observation of posture and gait are important in the initial evaluation of patients with degenerative lumbar scoliosis. It is important to view patients from the side to obtain an overall sense of sagittal alignment as well as any compensatory mechanisms. Standing posteroanterior and lateral 36-in (0.9-m) radiographs are necessary to evaluate alignment on initial and subsequent visits to follow curve progression. Progression is variable but averages about 3° per year25. Flexion and extension lateral radiographs are also important for surgical decision-making, as any instability manifested as spondylolisthesis should be treated with fusion to prevent further progression. The degree of osteophyte formation may help predict instability in the lumbar spine26. Magnetic resonance imaging (MRI) is useful for evaluating nerve root compression, disc degeneration, and modic changes (changes in signal intensity of the vertebral end plates and subchondral bone)27,28. Computed tomography (CT) myelography is particularly useful for patients with more severe deformity, to define the neural elements and areas of compression as well as anatomic changes associated with lateral listhesis29. Nonoperative Management A trial of nonoperative management is considered appropriate for most patients presenting with symptomatic degenerative scoliosis30,31. Patients usually present with symptoms related to either radiculopathy or claudication due to stenosis or to pain and functional impairment assumed to be a result of degeneration and deformity, either sagittal or coronal or both. Despite the usual practice of trying nonoperative treatment for degenerative scoliosis, we are not aware of any studies addressing its efficacy32,33. Medication can be used for relief of pain related to deformity and/or degeneration. Traditional recommendations include nonsteroidal anti-inflammatory drugs, muscle relaxers, and narcotics. A trial of physical therapy or its equivalent is appropriate for most patients32,34. Goals generally include optimization of core fitness, flexibility, and body mechanics as well as sensible modification of activity. Chiropractic evaluation and treatment can be considered for acute episodic pain, but evidence of its efficacy is mainly limited to case reports and small series35–38-38. More comprehensive treatment incorporating cognitive behavioral therapy, when available, may be optimal for chronic pain, as is the case for other types of degenerative conditions39,40. Interventional treatment, including epidural steroid injections, facet injections, or sacroiliac injections, are controversial because of questions about their long-term benefits, but they can be helpful for diagnostic as well as therapeutic purposes. Transforaminal epidural steroid injections may provide short-term relief for most patients, but their effectiveness decreases over time41. For neurogenic symptoms due to stenosis, nonoperative treatment similar to that used for spinal stenosis alone is reasonable42,43. Rehabilitation options and medications are similar to those described above, and membrane stabilizers, such as gabapentin, can be included as well. Epidural steroid injections in particular are more efficacious for neurogenic symptoms arising from nerve root compression41. Operative Indications Operative treatment can be considered for patients with stenosis and neurogenic symptoms that are not relieved by a course of nonoperative treatment. Most neurogenic symptoms related to stenosis are thought to be stable. While there is no firm time point at which to consider nonoperative treatment a failure, a minimum of six weeks is usually considered adequate. Accelerated surgical decision-making is indicated for progressive neurological deficits, especially cauda equina syndrome. Most operative treatment involves fusion to address the deformity along with decompression of the stenosis44. In isolated circumstances, limited decompression alone may be appropriate. For patients with risk factors for progression, such as a Cobb angle of >30°, lateral listhesis of ≥6 mm, or substantial apical vertebral body rotation, decompression alone may lead to progression25. There are no rigid guidelines for determining levels of fusion. At a minimum, the levels of decompression should be included. The remaining levels depend on the severity of the curve, the resulting sagittal and/or coronal imbalance, and any concurrent spondylolisthesis or lateral listhesis. Other indications for operative treatment are more ambiguous and may include intractable pain, patient dissatisfaction with the cosmetic appearance, a neurological deficit, and instability45–53-53. Patients with deformity-related pain, which is back pain due to postural abnormalities and muscular fatigue, should undergo a more extensive trial of nonoperative treatment; an operation before six months of dedicated treatment is rarely appropriate for such patients. When operative treatment is considered in the absence of radiculopathy, fusion is always indicated. Medical comorbidities as well as bone mineral density should be optimized and controlled, and modifiable risk factors such as smoking and morbid obesity should be corrected prior to operative treatment54,55. Bone mineral density can be evaluated with a DXA scan, and osteoporosis treatment regimens may be indicated. Symptoms should be correlated to the deformity and radiographic evidence of neurological compression, although this is more difficult than it is for neurogenic conditions. An operation to address progression of scoliosis is reasonable. There is no strict degree of progression or curvature that warrants operative treatment, but a lumbar curve of greater than 30° to 40° or progression of the curve of more than 10° have been cited30,31. In addition to progression over time, features such as spondylolisthesis, lateral listhesis, and positive sagittal balance beyond 5 cm merit consideration for surgery. The overall deformity is often addressed more completely in these patients compared with those with primarily radicular symptoms due to stenosis. Again there are no strict guidelines, and selection of the upper and lower levels of the operative reconstruction remains debatable56–59-59. Each patient must be evaluated individually, and levels must be selected on an individual basis. Patients should be well informed about the risks of operative treatment, which are far from infrequent or trivial. However, outcomes can be expected to be favorable in patients with optimized risk factors and substantial functional impairment despite nonoperative treatment and whose symptoms can be attributable to their deformity30,60. Operative Management Operative management can be considered for patients with degenerative scoliosis after conservative therapy has failed45–51-51. Many options are available for patients with degenerative scoliosis, and therefore treatment planning and intervention must be individualized. The goals of surgery include decompression of neural tissue and curve correction for restoration of spinal alignment and stability45–47-47,52,61–69-69. Operative techniques for thoracolumbar scoliosis are varied and can be performed through an anterior or posterior approach or both45–49-49,51,61,62,66,70–78-78. Posterior approaches are often for adult patients with curves or in patients with surgery the risk of to or of sagittal A combined approach is often useful in patients with rigid This the of anterior such as anterior of the with deformity correction and including of This is particularly common at the the risk of is the highest and the in of sagittal alignment is the In techniques as well as the lateral or approach have increased the for the management of degenerative without fusion is an for neurogenic claudication or radiculopathy in patients have deformity without instability or those more extensive This is and usually involves a and/or without have been reported to be lower in patients undergo decompression however, this should be for patients without with scoliosis, and with of a limited of spinal either alone or in with a posterior is a approach for treatment of The most common anterior surgery is anterior lumbar combined with anterior and/or posterior lumbar fusion is most useful in the lower thoracic and lumbar In selected the anterior approach deformity correction and patient The anterior approach of the disc along with the to disc which and in the restoration of of this include the risk of and The a of the anterior lumbar of the same as an anterior such as the of a and the to correction A and fusion can be performed with a and pedicle can be However, to the and disc is The risks associated with fusion are nerve root and In a of patients after the of the isolated hip This was in of the patients. studies have good outcomes with high fusion even over in patients treated with fusion and pedicle for degenerative in lumbar lordosis can be expected after In one of patients, lumbar lordosis was corrected from a of to a of at the time of a demonstrated of in lumbar lordosis but this of to at one with no in pelvic incidence or in pelvic lordosis radiographs of a patient with degenerative lumbar scoliosis. The patient has a coronal plane deformity, with the concavity on the There is also of lumbar lordosis seen on the lateral radiographs fusion at and and posterior fusion from T10 to the There is in the coronal plane deformity along with restoration of lumbar of spinal deformity surgery is the posterior approach. 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It is the most and is used in that be corrected with pedicle or or when the deformity is in the thoracic surgery for curve correction deformity and fusion and patient A and However, these are often associated with higher as the patient is to operative and greater of after thoracolumbar surgery for are generally reported to be higher than after other primarily because of the of the operation as well as a greater of comorbidities in patients with thoracolumbar There is a of reported to likely because of in patient populations and for Scoliosis Research of patients operative treatment for degenerative lumbar scoliosis demonstrated in patients but other smaller studies higher may also be related to the approach and surgical neurological include and compression due to primarily result from include epidural neurological deficit, and can include failure, and patients may have a higher risk of complications, but the to be In a of patients treated with decompression and pedicle age, years), there were and to surgery in patients. An age of more than years and or more comorbidities were associated with higher but the were not and was a predictor of In of patients older than years the most common major was and the most common was These increased with age as well as with the of the time, and more levels of a patient with degenerative lumbar scoliosis. The radiographs a deformity limited primarily to the lumbar spine. There is limited overall sagittal radiographs anterior lumbar fusion at and and posterior fusion from T9 to There is in coronal alignment along with restoration of lumbar in operative including and an to have to the overall and outcomes in surgery for deformity consideration for operative treatment is the of levels to including the and levels of the in have in outcome and the to and even in the of an with are not aware of any studies that compared operative and nonoperative treatment of degenerative lumbar scoliosis. studies operative and nonoperative treatment of adult scoliosis have compared with the patients were treated the patients surgery less back pain, lower-limb pain, and disability and greater in after years of studies have the outcomes of of surgical management of degenerative lumbar scoliosis. However, it is difficult to the of these studies as the operative techniques have varied The of operative treatment for degenerative lumbar scoliosis include decompression alone to associated stenosis and/or and fusion of the degenerative et compared these three treatment options in patients with degenerative lumbar scoliosis and radiculopathy with a minimum of years of The found that the degenerative lumbar curve not after decompression alone or fusion. Although curve fusion was associated with an in the degree of it was also associated with a higher to be with and less from the compared with decompression alone and Clinical and radiographic of posterior fusion for lumbar degenerative scoliosis are mainly limited to studies with relatively small patient and studied the at an of months decompression and posterior fusion for degenerative lumbar scoliosis and stenosis in forty patients with an age of The reported a substantial in back pain, with of the patients to no back pain after the surgery. The curve correction was In a of patients posterior lumbar decompression and fusion for degenerative lumbar scoliosis, et reported in the on for pain, the and the after an of of There have been a of studies on the and of anterior lumbar fusion through a lateral approach for the treatment of degenerative lumbar scoliosis. In a of patients fusion through a lateral approach for degenerative lumbar scoliosis, et that this approach the of the surgical management of this and the and radiographic outcomes of the lateral approach to anterior fusion for the treatment of degenerative lumbar scoliosis in patients. There was no These reported a compared with in for back and lower-limb pain, the and at an of years The in the Cobb angle was from to at the time of and there was a in lumbar A by et compared lateral fusion with decompression without fusion for the treatment of degenerative lumbar scoliosis. Patients decompression without fusion a Cobb angle of which to Patients lateral fusion a Cobb angle of which to The between the and Cobb between the approaches however, no outcomes were in this study. surgery alone may be for patients with curves and symptoms due to but fusion should be performed the patient has risk factors for progression. Sagittal such as the sagittal vertical axis, as well as spinopelvic parameters have to be of patient disability. Schwab et found that severe as by an of was likely in patients with pelvic tilt of a sagittal vertical of mm, and a pelvic lordosis of of the treatment of degenerative lumbar scoliosis and the that surgery may provide over nonoperative treatment that of other degenerative of the lumbar spine. The of this is by the of presenting degrees of deformity, and available surgical techniques for treatment. Degenerative lumbar scoliosis is a common that can lead to substantial functional disability. an population, it is important to further the nonoperative and operative treatment, and outcomes in these patients. in operative techniques to outcomes and when nonoperative treatment is studies are to define the most treatment