Debate: Determining the Upper Instrumented Vertebra in the Management of Adult Degenerative Scoliosis

Abstract

The determination of fusion levels for degenerative adult scoliosis requires a detailed evaluation of the spinal deformity and an analysis of the degenerative changes of the entire spinal pelvic axis. Choosing the upper instrumented vertebra (UIV) should be based on factors thought to be important to the overall survival of spinal segments adjacent to a spinal fusion. These factors include: starting with healthy adjacent segments with no degeneration or instability in any plane; stopping adjacent to spinal segments with normal sagittal, coronal, and axial alignment. Additionally, extending instrumentation to T10 or proximal may provide relative protection to the adjacent segment via increased stability afforded by the rib cage. From a clinical perspective, the postoperative sagittal balance appears to be the most critical factor in the patient's clinical outcome. Long-term follow-up of large, well-matched adult deformity cohorts will be required to determine the impact that each of these factors has on adjacent segment survival. Case Presentation: Harry Shufflebarger, MD Historical Data. The patient is a 60-year-old woman who previously led an active life. She enjoyed extensive travel, snow skiing, gardening, and many other activities. She has two children. For the past 2 years, she has noted a change in body shape, increasing lumbar pain, and inability to perform activities of daily living. She most recently developed bilateral posterior thigh pain with activity, occasionally extending to the left foot. Walking is now limited to 1 to 2 blocks, compared to 1 mile 6 months ago. The patient's symptoms have been refractory to nonsteroidal anti-inflammatory drugs, epidurals, facet blocks, and rest. She does not want to change her lifestyle. Past medical history is generally unremarkable. She has elevated serum cholesterol, well controlled on medication. There is no history of diabetes, cardiac problems, or other significant medical conditions. She does not smoke. Her father died at 87 of Alzheimer's disease. Her mother is alive and generally well at 83 years. There is a male sibling who is alive and well at age 62. Physical Examination. Height is 162 cm and weight is 53 kg. On standing, there is mild waist asymmetry and on forward bending there is a right lumbar rotational prominence. Neurologic examination reveals no motor, sensory, or reflex asymmetry. General physical examination reveals no abnormalities. Diagnostic Evaluation. Her diagnostic evaluation includes standing 36 in. anteroposterior and lateral scoliosis radiographs (Figure 1a), which reveal a 35° left L2–L4 degenerative scoliosis. Small proximal right thoracolumbar curve and right lumbosacral fractional curves with minimal rotation are appreciated. There is a lateral listhesis of L4 on L5. The center sacral line bisects T12, which is the proximal neutral vertebra as well. Coronal plane balance is normal. Standing lateral radiograph (Figure 1b, c) reveals multilevel lumbar disc degeneration extending from L2–L3–L5–S1, with significant loss of segmental lordosis from T12 to L4. Total lumbar lordosis (T12–S1) is decreased to 35°. This patient has normal global sagittal balance thanks in part to thoracic hypokyphosis. Bending radiographs (Figure 2) reveal a stiff primary lumbar curve and flexible secondary thoracolumbar and lumbosacral curves. Neurodiagnostic evaluation consists of MRI of the thoracolumbar spine and reveals advanced disc degeneration from L1–L2–L4–L5, and lateral recess and foraminal stenosis at L3–L4 and L4–L5.Figure 1: Erect AP (a), lateral (b), and close up (c) lateral lumbosacral junction.Figure 2: Right (a) and left (b) lateral bending radiograph.Based on this clinical information, I have asked each debate participant to support stopping at the UIV assigned to them. Dr. Suk was assigned the UIV T10, and Dr. Mardjetko was assigned L1. Debate: Se-Il Suk, MD This is a review of the literature and my own personal experience regarding the impact of the proximal extent of fusion on the outcome of the surgical treatment of degenerative lumbar deformity. My goal was to summarize the clinical problems and factors to be considered when selecting the UIV in a patient with degenerative lumbar deformity, identify proximal junctional problems, and evaluate results based on the choice of the UIV. Proximal junctional problems, consisting of proximal adjacent segment degeneration, compression fracture proximal to the UIV, or screw failure in the UIV, occurred more frequently with fusions ending at T11 to L2 as compared with those ending at T10 or above. Adult degenerative scoliosis is mainly observed in the lumbar spine and typically occurs in patients older than 60 years of age. Because of the increasing average life expectancy, coupled with more active senior lifestyles, degenerative lumbar deformity has become a common and disabling spinal condition.1,2 The literature offers the surgeon little guidance regarding the management of degenerative lumbar deformity. The prevalence of adult lumbar scoliosis had been reported to range from 2.5% to 15%.1,3 In our experience,2 the prevalence was 4.4% in adults in the fifth decade and 8.6% in those over 60 years of age, with a rapid increase after the sixth decade. Most degenerative lumbar deformities develop as a consequence of long-standing spondylotic disease.4–7 Although the details of the pathophysiology are still unknown, scoliosis, kyphosis, or a combination of these deformities originates from a rapid asymmetrical degeneration of lumbar intervertebral discs, facet joint degeneration, and osteoporosis.8,9 Typical radiographic findings of degenerative lumbar scoliosis are loss of lordosis, asymmetric disc narrowing, spondylosis, facet joint arthrosis, laminar hypertrophy, and marginal osteophyte formation. Degenerative lumbar scoliosis is usually characterized by a short reciprocating curve extending from T11 or T12 to L5 or S1. Usually, there is not significant scoliosis affecting the thoracic spine. Degenerative lumbar kyphosis may occur as the prominent deformity and has similar radiographic characteristics. In contrast to the asymptomatic adolescent with scoliosis, patients with degenerative deformity4 frequently present with mechanical low back pain, radicular pain, and/or severe neurogenic claudication that result in a limitation in their ability to stand or walk. A forward leaning posture may have its origin in muscle fatigue related to the coronal and sagittal plane imbalance or may be related to coexisting spinal stenosis.1,10 Back pain is more common in patients with lumbar curves who have facet arthropathy and/or degenerative discs.11 Patients with degenerative lumbar deformity often experience symptoms associated with central, lateral recess, or foraminal spinal stenosis. This may be associated with facet joint arthrosis, translational, lateral, or rotatory subluxations. Radiculopathy can occur secondary to compression of the nerve roots in the concavity of the curve or by traction on the nerve roots in the convexity of the curve. Paresis or paraplegia from untreated scoliosis in the absence of true kyphosis has not been reported.12 The psychologic burden of this disorder on these otherwise productive and healthy individuals is significant and should be considered when formulating the treatment plan. Many patients with degenerative lumbar scoliosis do not need surgical treatment, and their low back pain can be managed by conservative measures.13 However, there is a well-defined group of patients who present with severe intractable low back pain, spinal stenosis with radiculopathy or neurogenic claudication, and progressive spinal deformity in the coronal and sagittal plane. Surgical treatment may be indicated for these patients who do not respond to conservative treatment. Surgical treatment should consist of neural decompression, correction of sagittal and coronal plane deformity, and spinal stabilization via instrumented spinal fusion.5,14 The choice of fixation is extremely important since osteoporosis is commonly identified in patients with degenerative spinal deformity.12 Pedicle screw fixation is the only real option when the posterior elements are removed to decompress spinal stenosis. We have found that the pedicles are strong fixation points in patients who have osteoporosis. Lumbar pedicle screws are superior to hooks in achieving and maintaining lumbar curve correction. Pedicle screws also provide greater correction of compensatory curves above and below the instrumented levels. The pedicle screw acts anterior to the axis of rotation and allows for more correction of coronal and sagittal malalignment compared with any other type of fixation.15 In most instances, a one-stage posterior procedure can accomplish the primary surgical goals of stabilization, decompression, and a balanced correction to improve the patient's quality of life and functional status. This can be usually be achieved by decancellation procedures or osteotomies via a posterior procedure, thus avoiding an anterior procedure with its longer operative time, increased intraoperative blood loss, and negative effect on pulmonary function.16–18 Anteroposterior procedures may be considered in patients with fixed lumbar deformity, which is not passively correctable to a satisfactory degree. Surgery for degenerative deformity is often associated with high rates of complications. These include pseudarthrosis, instrumentation failure, junctional problems, and higher general medical morbidity. The major concerns in long fusions for degenerative lumbar deformities have been focused on the distal fusion level at L5 or S1 and distal instrumentation failure, but there are few written reports about proximal extent of fusion and its outcomes in degenerative lumbar deformity correction. Factors to be Considered in Selecting the UIV. Most patients with degenerative lumbar deformity have spinal stenosis at several levels, causing neurogenic claudication and/or radiculopathy. The extent of the pathology demands stabilization from the thoracolumbar to the lumbosacral junction. Wide posterior decompression with lateral recess and foraminal decompression is necessary to relieve symptoms of spinal stenosis. Spinal stabilization with a long lumbar construct is required to prevent spinal instability and progression of the spinal deformity.19,20 Deformity correction may be achieved by several methods, including rod derotation, cantilever reduction maneuvers, and distraction/compression maneuvers. Distraction in the concavity should be done with caution to avoid loss of lumbar lordosis. Deformity correction achieves an indirect neural decompression as well. The surgeon should not end the instrumentation at a segment with: 1) posterior column deficiency, 2) listhesis in any direction, 3) a rotated spinal segment, 4) a region of junctional kyphosis, or 5) at the apex of deformity in coronal and sagittal plane. The importance of restoring lumbar lordosis and sagittal balance has been reported in the literature. Decreased lumbar lordosis and poor sagittal balance have been correlated with pain and functional loss.21–23 Reconstitution of sagittal alignment can be performed by spinal osteotomy. Restoration of the anterior column using structural anterior column support may be achieved by anterior, posterior, or transforaminal lumbar interbody fusion techniques. The thoracolumbar junction (T10-L2) has unique anatomic characteristics. It serves as the transition from the immobile thoracic spine to the lumbar spine. There is a change in the of the facet from the coronal plane to the sagittal plane The sagittal alignment changes from thoracic kyphosis to lumbar lordosis. the true to increase the stability of the thoracic spine the thoracic rib cage. The rib the of the the thoracic spine greater to bending in the sagittal, coronal, and axial The upper thoracic this mechanical support the true but T11 and T12 have These levels the support by the the joint and the at or distal to T11 and T12 the adjacent segment at a to the to the in the proximal segments after long fusion for degenerative lumbar deformity consist of 1) proximal adjacent segment degeneration, 2) compression fracture proximal to the fusion or 3) screw failure at the instrumented Proximal adjacent segment degeneration can be by the of the findings in the proximal adjacent 1) progressive of disc 2) progressive in lordosis or increase in kyphosis, 3) osteophyte and of adjacent or 4) in coronal or sagittal A review of the literature on this the of this surgical outcomes in long lumbar fusions from or L2 to S1 done for a of spinal including degenerative spinal scoliosis, pseudarthrosis, and patients required for at or above the UIV, adjacent segment degeneration, or 2 patients had or clinical that instrumented lumbosacral fusions with UIV at or L2 have an high mechanical failure in adult patients and be In a reported adjacent segment problems in of patients who had lumbar fusion extending to or that the proximal level requires of the and vertebra in the coronal and sagittal typically the fusion at T10 or T11 in adult lumbar scoliosis We our with degenerative lumbar deformity patients who fusion to L5 or S1 with the of the impact that the choice of the UIV has on the adjacent In I fusion proximal to or In fusion to T11 or In fusion to or The apex of their deformity was below on coronal and/or sagittal the had scoliosis had kyphosis and had and kyphosis average age at the was years, by a posterior procedure using segmental pedicle screw and had a follow-up of 2 years distal fusion at L5 or S1 and patients who had distal instrumentation failure decompression at the levels was performed in patients or was in patients The was with a blood loss of in with in and with in 1: The of Patients or to the of I and patients had proximal adjacent problems in contrast to in of sagittal balance follow-up occurred in of of and of Coronal balance and correction well follow-up in 2: The of Patients Proximal that this is limited by short follow-up and We have recently of most of these patients with minimal follow-up of years and have similar longer follow-up of a will be necessary to these We found that the patient in the related to of using the for the UIV. She developed proximal adjacent degeneration at 2 years after the Many and clinical have that increased and increased are associated with adjacent segment and at this can instrumentation failure and adjacent segment A woman with low back pain, bilateral radicular pain, and claudication for years. and The radiographs a degenerative lumbar scoliosis. and She posterior decompression to posterior lumbar interbody fusion at with and pedicle screw instrumentation L2 to S1 with correction of her scoliosis. and The radiographs at 2 6 years after proximal adjacent with junctional kyphosis and stenosis at and of fusion to T10 with pedicle screw fixation and anterior lumbar interbody fusion with The radiographs at 2 years after fusion junctional to the proximal fusion to the upper thoracic spine This more levels of fusion and is by greater and increased operative time, and intraoperative blood loss, In proximal adjacent segment problems and sagittal imbalance more common when proximal fusion from T11 to I extending fusion to T10 or above to a longer survival of the adjacent segments in the surgical treatment of degenerative lumbar deformity. Debate: MD Adult scoliosis is by the as the of coronal plane deformity in individuals after age The of adult scoliosis on the age at In the deformities can be managed using and to adolescent starting in and extending the of the adult scoliosis is characterized by the progression of coronal plane deformity that is usually stiff by the multilevel degeneration of facet and of the lumbar and lumbosacral spinal deformity. The degenerative to the of lumbar segmental and kyphosis, and the patient's global sagittal balance may be by and lumbar kyphosis, as well as degenerative kyphosis and disc and facet can result in coronal sagittal and rotational segmental lateral recess, and of spinal stenosis result in radicular and neural claudication The surgical management of adult scoliosis is based on the of problems with which the surgeon is The surgical to be to the patient's The surgical treatment will need to the spinal stenosis with the necessary neural The lumbar and lumbosacral fractional curves need to be via facet joint plane deformity to be on a segmental or a with anterior and structural anterior posterior or The goals should be to of the sagittal balance in the coronal and the necessary neural For a fusion be This surgical treatment should be done with stabilization to segments sagittal and coronal plane alignment at the and global Because of the of adult spinal deformity, the surgeon the upper and end based on the patient's spinal deformity, sagittal and the extent of the degenerative In most adult lumbar the surgeon to the occasionally stopping at L5 may be This is the of debate in this should the fusion on a review of the with to the proximal level have been advanced by The proximal end vertebra should be in the by the coronal axis the coronal plane deformity the UIV should be in the coronal the superior and the adjacent disc in the plane. this should associated with a disc The upper end vertebra should for of the sagittal alignment the instrumented segments and should as the transition to proximal segments in the sagittal plane. There should be little or no disc or the facet joint degeneration of the adjacent spinal The upper end vertebra should have neutral or neutral The adjacent segments should be in and the posterior elements should be these a upper end vertebra will on the patient's degenerative curve and sagittal The upper end vertebra usually from to L2 when a lumbar based on evaluation of degenerative and sagittal plane alignment. In most patients with primary degenerative lumbar curves and thoracic and thoracolumbar sagittal the surgeon can the fusion in the thoracic or upper lumbar spine from T10 to coronal plane correction and balance should be has been that patient outcome is most associated with sagittal plane and sagittal It is critical that the surgeon do in to or to a normal sagittal Long-term of the patient's spine after scoliosis fusion is an important secondary the surgical have been to the of these spinal the choice of the upper and instrumented vertebra have an impact on spinal fusion The short is follow-up of the adolescent the choice of instrumented vertebra has a effect on the of the adjacent spinal with fusions to L4 in of the adjacent segments to years, and fusions to or above generally Dr. Suk the that the choice of the UIV in adult degenerative scoliosis may have a similar impact on spinal construct and adjacent segment degeneration in the adult degenerative scoliosis are the by which an adult deformity procedure may be there are segment degeneration is a of failure that will occur at any spinal segment adjacent to an instrumented spinal fusion in It has a reported of at factors for this include sagittal plane adjacent segment degeneration, sagittal or coronal and facet joint This has been in adolescent scoliosis is associated with junctional segment failure, may present as adjacent segment degeneration with or spinal stenosis and segmental The is thought to be to the progression of the degenerative coupled with the surgical effect of spinal by this to the I have adjacent segment degeneration at spinal my no spinal region has to this adjacent segment degeneration with instability at and in the patient over a (a) segment degeneration at at years after a T12 to fusion. Degenerative instability and are This required to (b) The patient in at years after to with of adjacent segment degeneration at with degenerative instability and and to A to fusion for years a (a) with in an This was associated with severe multilevel spinal stenosis and reduction and posterior decompression was performed the and a rod of the UIV, or of adjacent or have been as an and in the adult deformity and sagittal balance to be Most these occur in or adjacent to the UIV (Figure but occasionally may be identified many segments proximal to the UIV (Figure of the pedicles or the of the UIV that occur in the postoperative can construct with loss of proximal segment increased of pseudarthrosis, and loss of correction in sagittal and coronal Additionally, pain in the region may be secondary to of the and that can occur at any after This diagnostic should be considered in the clinical (a) A compression fracture at T10, the vertebra proximal to the UIV at months (b) A compression fracture noted at months The UIV is progression of thoracic kyphosis (Figure is a increase in thoracic kyphosis that does not to be to a segment This may be to progressive disc degeneration associated with of spinal commonly with the is an of a T10 to fusion in which a increase of kyphosis was noted over years. to the sagittal balance (Figure A patient scoliosis fusion T10 to progression of thoracic kyphosis from to or failure was noted over years of follow-up (a), proximal to in spinal in and thoracic spinal may be and management (Figure usually these are managed of the spinal deformity, occasionally spinal may be necessary to the patient's spinal and The spine surgeon be of degenerative of the and that can to sagittal imbalance and the patient's outcome. Suk has that stopping at thoracic and upper lumbar segments results in degeneration of the adjacent segments do to the of these has the that is to fusion to or T10 in is based on a of instrumentation in an spinal this on own a with has the of greater blood loss and increased surgical This is in own In there is increased associated with of instrumentation the thoracolumbar greater of with the of the thoracolumbar and greater associated with the need for more The of a may result in fusion of to spinal segments in the of transition may be by the choice of the proximal segment, to there is no that can the that to T10 the results not greater The to determine factors that may be operative in transition be to patients for long of in these may perform a of the adjacent segments of adult scoliosis in this will be to the of the are not for to this change in my own Harry Shufflebarger, MD extensive this patient to surgical treatment. on her sagittal was that a procedure be This procedure was as is the experience that this most lumbar lordosis and achieves coronal correction. I includes posterior bilateral pedicle screw at level from T12 to and bilateral screw in the is performed in is achieved by from to and the posterior is a posterior lordosis by anterior In my lumbar facet usually the of anterior the posterior in not the anterior consists of anterior lumbar interbody fusion via a left with and from at each each is anterior to the The was with from the The anterior procedure of lumbar lordosis, coronal plane and the fusion rod segmental correction via compression and posterior lateral fusion from T12 to the The goal is to segmental lumbar lordosis and coronal plane correction. and the The for selecting T12 as the proximal instrumented level is based on several radiographic On the standing anteroposterior radiograph (Figure 1a), the T12 vertebra is by the center sacral line and is neutral in the vertebra is In my stopping on a rotated vertebra appears to adjacent segment On the standing lateral radiograph (Figure the segment no degeneration, no and no segmental The thoracolumbar junction alignment is and there is thoracic extending to the proximal thoracic This sagittal balance is normal. was not that the fusion had to be proximal to The sagittal MRI reveals little or no disc degeneration in the thoracolumbar junction. and lateral standing radiographs at 2 years reveals coronal plane and of normal sagittal alignment. The disc appears (a) Erect postoperative anteroposterior radiograph reveals coronal plane deformity correction with a T12 to (b) Erect lateral radiograph reveals of lumbar lordosis, normal thoracolumbar junction and normal sagittal (c) lateral of lumbar spine reveals of the lumbar lordosis the instrumented spinal segments T12 to achieved with segmental anterior column the this patient is has most of her and is most with her outcome to I that 2 years is a short follow-up and that and adjacent segment changes may become in the It is that changes in the patient's sagittal and adjacent segment degeneration will occur with of which UIV is The patient and should be of this the surgeon should the surgical procedure to each patient's in with the that the goal of surgical is to a and spine with the of segments I to for the and in their assigned