Flatback Syndrome

doi:10.1016/j.nec.2007.01.007

Neurosurgery Clinics of North America

Volume 18, Issue 2, April 2007, Pages 289-294

https://doi.org/10.1016/j.nec.2007.01.007 Get rights and content

Flatback syndrome is characterized by loss of normal lumbar lordosis, resulting in forward tilt of the trunk, inability to stand erect, back pain, and thigh pain from chronic hip flexion and knee bending. The usual etiology is iatrogenic, through previous fusions or with extension instrumentation. Surgical treatments described include extension osteotomy (Smith-Petersen), pedicle subtraction osteotomy, and polysegmental osteotomies.

Section snippets

Iatrogenic causes of flatback syndrome

A broad spectrum of causes leads to flatback syndrome. The identified factors that contribute to this include placement of distraction instrumentation in the lower lumbar spine or sacrum, pseudoarthrosis resulting in loss of sagittal plane correction, fixed thoracic hyperkyphosis, hip flexion contractures, and preexisting thoracolumbar kyphosis [2]. The most commonly reported cause of flatback syndrome is extension of distraction instrumentation into the lower lumbar spine or sacrum [3], [4],

Clinical presentation

Flatback syndrome is characterized by forward inclination of trunk, difficulty in standing erect with the knees fully extended, and pain as a result of loss of lumbar lordosis. To compensate for the loss of lumbar lordosis and to stand erect, the patient flexes the hips and knees, with cervical extension to maintain an upright horizontal gaze. This abnormal posture puts stress on the cervical, thoracic, and lumbar spine, resulting in fatigue and pain. Physical examination reveals flattening of

Radiographic evaluation

Sagittal curvature in the thoracic and lumbar spine has also been used to assess pathologic imbalance. Normal functional ranges vary widely; however, it is generally accepted that normal thoracic kyphosis ranges from 20° to 50° and that normal lumbar lordosis ranges from 20° to 65°. Additionally, the thoracolumbar junction should be straight [20], [21].

Formally, the workup for flatback syndrome should include a standing full-length, 36-in lateral radiograph with extension of the knees.

Nonsurgical treatment of flatback syndrome

Exercises to increase hip and back extension, pain medication, and bracing are all used as first-line nonoperative treatment options. In the only study of nonoperative treatment of flatback syndrome, only 27% of patients were ultimately considered to have a long-term successful result of nonoperative management [10]. This percentage is probably lower, however, considering that the mean sagittal imbalance in this group of nonoperative patients was only 3.4 cm. Conservative medical management is

Treatment

The goal of corrective surgery is to restore physiologic lordosis and sagittal balance so that the plumb line intersects the posterosuperior aspect of the sacrum. This should allow the patient to stand erect without compensatory flexion of the knee and hyperextension of the hip. The decision regarding placement of the osteotomy depends on the site of deformity. In general, corrective osteotomies should be performed at the site of maximal deformity. Patients with flattening of the lumbar spine

Extension (Smith-Petersen) osteotomy

In 1945, Smith-Petersen and colleagues [27] described a posterior osteotomy for correction of fixed sagittal deformity in patients with rheumatoid arthritis. This procedure involved resecting the posterior elements, undercutting the adjacent spinous processes, and closing the osteotomy. The name of this technique originates from the closure of this osteotomy by creating an opening of the spine (extension) anteriorly into the disc space, with the posterior aspect of the disc space as the axis of

Pedicle subtraction osteotomy

In contrast to the extension osteotomy, the pedicle subtraction osteotomy is a procedure that corrects deformity without lengthening the anterior spine. Pedicle subtraction osteotomy is a transpedicular cortical decancellation procedure. It achieves correction by a three-column posterior closing wedge osteotomy hinging on the anterior cortex and has been attributed first to Thomasen [33]. This procedure involves removal of posterior elements, including the pedicle, transverse process, and

Polysegmental osteotomies

The previously described complications in extension osteotomy can be avoided by polysegmental osteotomies. This technique was first reported by Wilson and Turkell [37] for correction of sagittal balance in a patient with ankylosing spondylitis and involves removing the facet joints at several levels and then compressing the posterior elements to create lordosis. In contrast to extension osteotomy, this correction is obtained through deformation of disc spaces without rupture of the anterior

Comparison of techniques

Each of the previously described surgical techniques addressing sagittal imbalance has its advantages and disadvantages. In 1999, Van Royen and De Gast [39] performed a meta-analysis of polysegmental, pedicle subtraction, and Smith-Petersen osteotomies in the treatment of ankylosing spondylitis. Their review included 16 studies with a total of 523 patients. Pedicle subtraction osteotomy provided more correction than polysegmental and Smith-Petersen osteotomies, and complication rates tended to

Summary

Recently, iatrogenic flatback syndrome has increased because of the trend of increased long-segment thoracolumbar instrumentation and fusion. Patients present with difficulty in standing erect without flexing the knees or hyperextension of the hips, and this often leads to chronic back pain that is refractory to conservative medical therapy. The initial workup must include a 36-in standing lateral spine radiograph with the patient standing erect with the hips and knees extended. The exact

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Cited by (46)

Postoperative complications following Schwab-grade-I versus Schwab-grade-II PCO in treating severe rigid kyphoscoliosis patients: comparative matched-group outcomes with minimum 2-year follow-up
2023, Spine Journal
Standard partial facetectomies, (Smith-Petersen Osteotomy, (SPO), (Schwab-grade-I) and complete facet resection also known as Ponte osteotomy, (PO), (Schwab-grade-II) are narrowly akin and collectively appreciated as posterior column shortening osteotomies (PCOs). The former is considered a gentler osteotomy grade than the latter. The spine literature provides very little information on their comparison regarding perioperative complications and major curve correction rate outcomes.
To determine whether Schwab-grade-I PCO (SPO) and Schwab-grade-II PCO (PO) are comparably safe in the surgical management of severe rigid scoliosis or kyphoscoliosis patients.
Retrospective single-center comparative clinical study.
A total of 38 patients with severe rigid scoliosis or kyphoscoliosis were propensity score matched in this study, (SPO-treated); n=21 (55.30%) and (PO-treated); n=17 (44.70%), who underwent primary spinal deformity corrective surgery, respectively.
Outcomes included demographics, baseline pulmonary functional outcomes, perioperative complications incidence, hospital costs, Oswestry disability index (ODI), and the Scoliosis Research Society-22 (SRS-22) questionnaire scores.
Following approval by the Institutional Review Board (IRB) of Beijing Chaoyang Hospital-Affiliated Capital Medical University in Beijing, out of a total of 82 consecutive surgical patients with complete data demonstrating severe and/or rigid spinal deformity, a pool of 38 of the 82 (46.3%) propensity-matched adult (≥18 years) patients with severe rigid scoliosis or kyphoscoliosis defined with a preoperative major curve magnitude of ≥80° on anteroposterior plain radiographs, and flexibility of <25% on bending plain radiographs who underwent primary spinal deformity corrective surgery were retrospectively evaluated. The patients were dichotomized into two osteotomy groups: standard (partial) facetectomy (SPO-treated), n=21 with an average age of 24.67 years, (Schwab-grade-I PCO) and complete facet excision, (PO-treated), (ie, Schwab-grade-II PCO), n=17 with an average age of 23.12 years. The minimum follow-up period was 2 years. Primary outcomes included baseline demographics and clinical features. Secondary outcomes included perioperative [intraoperative, immediate, and 2-year postoperative] complication rates. Tertiary outcomes included perioperative ODI and SRS-22 scores. Statistical analyses were carried out by Student t-test and Pearson's Chi-square test (Fisher's Exact Test), through Python statistical software package. Statistical significance was set at (p<.05).
Of the 38 matched severe rigid scoliosis or kyphoscoliosis patients, 55.30% (n=21) were SPO-treated and 44.70% (n=17) were PO-treated patients, respectively. The overall average age of patients was 23.97 years, with a female incidence of 76.32%. Major curve correction rates were 49.19% and 57.40% in SPO-treated and PO-treated patients, respectively, (p>.05). Immediately following surgery, comparable overall complication rates of 28.57% (n=6/21) versus 29.41% (n=5/17) were observed in the SPO-treated and PO-treated patients, respectively, (p=.726). We observed incidences of 9.52%, (n=2/21) versus 5.88%, (n=1/17) for surgical intensive care unit (SICU) admission, and incidences of 4.76%, (n=1/21) versus 5.88%, (n=1/17) for cardiopulmonary events in SPO-treated versus PO-treated patients following corrective surgery, respectively, (p>.05). The incidences of neurological deficits in the SPO-treated and PO-treated patients were respectively, 14.29%, (n=3/21) versus 17.65%, (n=3/17) immediately following surgery, (p>.05), and 0.00%, (n=0/21) in SPO-treated versus 14.28%, (n=3/21) in PO-treated patients at ≥2 years postoperative, (p<.05). Among the three patients that reported neurological deficits in the PO-treated group at ≥2 years postoperative, two patients had pre-existing baseline neurological deficits. The ODI score in the PO-treated group was significantly inferior at a minimum 2-year follow-up, (p<.05).
In the current study, both SPO-treated and PO-treated patients demonstrated statistically comparable surgical complications immediately following corrective surgery. Severe rigid kyphoscoliosis patients with preexisting baseline neurological deficits were more inclined to sustain neurological morbidity following corrective surgery. PCO corrective techniques are warranted as safe options for treating patients with severe rigid spine deformity phenotypes.
Indications
2021, Revision Lumbar Spine Surgery
Revision lumbar spine surgery is associated with several distinct pathological processes after an index spine surgery. Common complications that warrant surgical revision include adjacent segment pathology, pseudarthrosis, implant failure, flatback syndrome, recurrent/residual stenosis or disc herniation, and wound complications. Preoperative consideration of these potential complications at the index surgery may mitigate the need for revision surgery, but many of these issues are unavoidable.
Successful detection of postoperative improvement of dynamic sagittal balance with a newly developed three-dimensional gait motion analysis system in a patient with iatrogenic flatback syndrome: A case report
2018, Journal of Clinical Neuroscience
Citation Excerpt :
Iatrogenic flatback syndrome is a sagittal kyphotic deformity with postoperative lumbar lordotic reduction because of lumbar spinal fusion at an unsuitable lumbar lordosis and injury of posterior tissue by posterior spinal decompression/fusion [1,2].
A 75-year-old Japanese woman with Parkinson’s disease complained of lower back pain and gait disturbance because of iatrogenic flatback syndrome. The preoperative global spinal parameters were as follows: C7SVA, 168 mm; TK, 52°; LL, −0.8°; PI, 57°; PT, 55°; TPA, 60°. We performed 3D gait analysis using a VICON System and calculated the dynamic SVA. Preoperatively, her flexion deformity gradually progressed during walking. The dynamic parameters gradually increased as follows: thoracic SVA, 216–241 mm; lumbar SVA, 53–69 mm; spinal SVA, 270–311 mm. We performed two-stage corrective surgery. Her lower back pain and gait disturbance significantly improved. The postoperative global spinal parameters were as follows: C7SVA, 1 mm; TK, 47°; LL, 61°; PI, 52°; PT, 20°; TPA, 13°. Dynamic SVA detected by our 3D gait analysis using VICON were as follows: thoracic SVA, 128 mm; lumbar SVA, 4.9 mm; and spinal SVA, 133 mm. The postoperative dynamic SVA did not change during walking.
This is the first report of a patient with iatrogenic flatback syndrome whose postoperative improvement of dynamic spinal sagittal alignment was successfully detected with a newly developed 3D gait analysis system that enabled us to analyze a dynamic change of SVA based on the patient’s actual walking with a continuous long-distance gait. Our 3D gait analysis has potential usefulness for evaluating postoperative sagittal balance for iatrogenic flatback syndrome.
Effect of Single-Level Transforaminal Lumbar Interbody Fusion on Segmental and Overall Lumbar Lordosis in Patients with Lumbar Degenerative Disease
2018, World Neurosurgery
Citation Excerpt :
Physiologic lumbar lordosis (LL) is a key feature in maintaining sagittal spinal balance. Patients with lumbar degenerative disease are characterized by a significant reduction in whole lumbar lordosis (WLL) and resultant sagittal spinal malalignment.1,2 Lumbar interbody fusion is a common surgical procedure for the management of lumbar degenerative disease.
To investigate the ability of transforaminal lumbar interbody fusion (TLIF) to improve lumbar lordosis (LL).
In this retrospective study, 92 patients undergoing single-level TLIF to treat lumbar degenerative disease were divided into a low back pain, radiculopathy, and neurogenic claudication group according to their symptoms. Preoperative and postoperative measures, including segmental LL, whole LL, pelvic incidence (PI), pelvic tilt, thoracic kyphosis, sagittal vertical axis, visual analog scale for back and leg pain, and Oswestry Disability Index, were used to evaluate radiographic and clinical outcomes.
All clinical parameters were significantly improved after TLIF. There was no significant difference in any radiographic parameters in the low back pain group. In the radiculopathy and neurogenic claudication groups, all radiographic parameters were significantly changed after TLIF except for segmental LL and PI in both groups and pelvic tilt in the radiculopathy group. No statistically significant differences were found in improvement of segmental LL, PI, thoracic kyphosis, and visual analog scale (leg) between the radiculopathy and neurogenic claudication groups, whereas the differences in improvement of whole LL, pelvic tilt, PI-LL, sagittal vertical axis, visual analog scale (back), and Oswestry Disability Index were significant between the 2 groups.
For patients with neurogenic leg symptoms owing to single-level lumbar degenerative disease, whole LL was improved after TLIF as a result of spontaneous restoration of lordosis at the unfused lumbar levels.
Radiological lumbar stenosis severity predicts worsening sagittal malalignment on full-body standing stereoradiographs
2017, Spine Journal
Citation Excerpt :
As opposed to the DLS patient, compensatory mechanisms in adult spinal deformity (ASD) have been well described. The “driving force” behind the sagittal deformity is typically a mismatch between pelvic incidence (PI) and lumbar lordosis (LL), from degeneration, trauma, or iatrogenic fusion [3–6]. Although less common, sagittal plane deformity may also come from thoracic or cervical kyphosis.
Patients with degenerative lumbar stenosis (DLS) adopt a forward flexed posture in an attempt to decompress neural elements. The relationship between sagittal alignment and severity of lumbar stenosis has not previously been studied.
We hypothesized that patients with increasing radiological severity of lumbar stenosis will exhibit worsening sagittal alignment.
This is a cross-sectional study.
Our sample consists of patients who have DLS.
Standing pelvic, regional, lower extremity and global sagittal alignment, and health-related quality of life (HRQoL) were the outcome measures.
Patients with DLS were identified from a retrospective clinical database with corresponding full-body stereoradiographs. Exclusion criteria included coronal malalignment, prior spine surgery, spondylolisthesis>Grade 1, non-degenerative spinal pathology, or skeletal immaturity. Central stenosis severity was graded on axial T2-weighted magnetic resonance imaging (MRI) from L1–S1. Foraminal stenosis and supine lordosis was graded on sagittal T1-weighted images. Standing pelvic, regional, lower extremity, and global sagittal alignment were measured using validated software. The HRQoL measures were also analyzed in relation to severity of stenosis.
A total of 125 patients were identified with DLS on appropriate imaging. As central stenosis grade increased, patients displayed significantly increasing standing T1 pelvic angle, pelvic tilt, sagittal vertical axis, and pelvic incidence-lumbar lordosis (p<.05). No significant difference wasfound in pelvic incidence, supine lordosis, thoracic kyphosis, or T1 spinopelvic inclination between central stenosis groups. Despite similar supine lordosis between stenosis groups, patients with Grades 2 and 3 stenosis had less standing lordosis, suggesting antalgic posturing. Upper lumbar (L1–L3) stenosis predicted worse alignment than lower lumbar (L4–S1) stenosis.
Increasing severity of foraminal stenosis was associated with reduced lumbar lordosis; however, no significant postural difference in lordosis, thoracolumbar, or lower extremity compensatory mechanisms were noted between foraminal stenosis groups. Stenosis grading did not predict worsening HRQoLs in central or foraminal stenosis.
Severity of central lumbar stenosis as graded on MRI correlates with severity of sagittal malalignment. These findings support theories of sagittal malalignment as a compensatory mechanism for central lumbar stenosis.
When is compensation for lumbar spinal stenosis a clinical sagittal plane deformity?
2016, Spine Journal
Degenerative lumbar stenosis (DLS) patients have been reported to lean forward in an attempt to provide neural decompression. Spinal alignment in patients with DLS may resemble that of adult spinal deformity (ASD). No previous studies have compared and contrasted the compensatory mechanisms of DLS and ASD patients.
This study aimed to determine the differences in compensatory mechanisms between DLS and ASD patients with increasing severity of sagittal spinopelvic malalignment. Contrasting these compensatory mechanisms may help determine at what severity sagittal malalignment represents a clinical sagittal deformity rather than a compensation for neural compression.
This is a retrospective clinical and radiological review.
Baseline x-rays in patients without spinal instrumentation, with the clinical radiological and diagnoses of DLS or ASD, were assessed for patterns of spinopelvic compensatory mechanisms. Patients were stratified by sagittal vertical axis (SVA) according to the Scoliosis Research Society-Schwab [SRS-Schwab] classification.
Radiographic spinopelvic parameters were measured in the DLS and ASD groups, including SVA, pelvic incidence−lumbar lordosis mismatch (PI−LL), T1 spinopelvic inclination (T1SPi), T1 pelvic angle (TPA), and pelvic tilt (PT).
The two diagnosis cohorts were propensity-matched for PI and age. Each group contained 125 patients and was stratified according to the SRS-Schwab classification. Regional spinopelvic,lower limb, and global alignment parameters were assessed to identify differences in compensatory mechanisms between the two groups with differing degrees of deformity. No funding was provided by any third party in relation to carrying out this study or preparing the manuscript.
With mild to moderate malalignment (SRS-Schwab groups “0,” or “+” for PT, PI−LL, or SVA), DLS patients permit anterior truncal inclination and recruit posterior pelvic shift instead of pelvic tilt to maintain balance, while providing relief of neurologic symptoms. Adult spinal deformity patients with mild to moderate deformity recruit pelvic tilt earlier than DLS patients. With moderate to severe malalignment, no significant difference was found in compensatory mechanisms between DLS and ASD patients.
Patients with DLS permit mild to moderate deformity without recruiting compensatory mechanisms of PT, reducing truncal inclination and thoracic hypokyphosis to achieve neural decompression. However, with moderate to severe deformity, their desire for upright posture overrides the desire for neural decompression, evident by the adaptation of compensatory mechanisms similar to that of ASD patients.

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Flatback Syndrome

Section snippets

Iatrogenic causes of flatback syndrome

Clinical presentation

Radiographic evaluation

Nonsurgical treatment of flatback syndrome

Treatment

Extension (Smith-Petersen) osteotomy

Pedicle subtraction osteotomy

Polysegmental osteotomies

Comparison of techniques

Summary

Arch Phys Med Rehabil

Am J Surg

Complications of fusion in lumbar scoliosis. Proceedings of the Scoliosis Research Society

J Bone Joint Surg Am

The iatrogenic loss of lumbar lordosis

Orthop Trans

The lumbar lordosis below Harrington instrumentation for scoliosis

Spine

The effect of Harrington instrumentation on sagittal configuration and mobility of the spine in scoliosis

Spine

The effect of Harrington rod contouring on lumbar lordosis

Spine

Treatment of symptomatic flatback after spinal fusion

J Bone Joint Surg Am

Loss of lumbar lordosis. A complication of spinal fusion for scoliosis

Orthop Clin North Am

Surgical treatment of adult scoliosis. A review of two hundred and twenty-two cases

J Bone Joint Surg Am

Adult idiopathic scoliosis treated by posterior spinal fusion and Harrington instrumentation

Spine

Management of flatback and related kyphotic decompensation syndromes

Spine

Posterior osteotomies with pedicle substraction for flat back and associated syndromes. Technique and results of a prospective study

Bull Hosp Jt Dis

Complications and predictive factors for the successful treatment of flatback deformity (fixed sagittal imbalance)

Spine

Prevention and management of iatrogenic flatback deformity

J Bone Joint Surg Am

Long-term anatomic and functional changes in patients with adolescent idiopathic scoliosis treated by Harrington rod fusion

Spine

Gait abnormalities arising from iatrogenic loss of lumbar lordosis secondary to Harrington instrumentation in lumbar fractures

Spine

Long-term follow-up of scoliosis fusion

J Bone Joint Surg Am

Spinal fusions to the sacrum in adults with scoliosis

Spine