Tag: sagittal imbalance

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The effect of paraspinal sarcopenia on postoperative sagittal balance: a multivariate analysis following multilevel lumbar fusion surgery

The Spine Journal 26 (2026) 709−719

This clinical study examines how paraspinal sarcopenia influences long-term sagittal alignment and functional outcomes after multilevel posterior lumbar interbody fusion. Using preoperative MRI/CT and serial radiographs, muscle cross-sectional area, fat infiltration, and spinopelvic parameters were measured to compare sarcopenic and nonsarcopenic patients over at least two years.

Results show multifidus atrophy and fatty infiltration, plus inadequate preoperative lumbar and segmental lordosis, independently predict postoperative sagittal imbalance and worse pain and disability. The authors recommend preoperative paraspinal muscle assessment, nutritional and rehabilitation optimization, and tissue-sparing techniques to improve long-term outcomes.

Study aim: Assessed how paraspinal sarcopenia affects long-term sagittal alignment and persistent pain/disability after multilevel posterior lumbar interbody fusion (PLIF), and identified risk factors for postoperative sagittal imbalance.

Design & cohort: Retrospective single-institution study of 213 multilevel PLIF patients with imaging follow-up through ≥2 years; sarcopenic (n=69) vs nonsarcopenic (n=143/144) groups were compared.

Sarcopenia definition: Grouping based on psoas muscle index (MI) at L3 with thresholds <6.36 cm²/m² (men) and <3.92 cm²/m² (women).

Key measurements: Quantified L3 psoas/erector spinae/multifidus muscle MI, fat infiltration (Goutallier grading), and muscle density (CT HU); tracked spinopelvic parameters including LL, SL, PT, PI-LL, SVA plus VAS and ODI outcomes.

Muscle differences by group: Sarcopenic patients had lower muscle indices and higher fat infiltration (especially erector spinae and multifidus), with no significant difference in muscle density reported.

Alignment & outcomes: Sarcopenic patients showed worse long-term sagittal alignment at final follow-up (differences in LL, SL, PT, PI-LL, SVA) and worse long-term VAS and ODI scores, despite similar preoperative clinical scores.

Independent risk factors: Multifidus atrophy (lower MMI) and multifidus fat infiltration plus insufficient preoperative LL and SL were independent predictors of long-term postoperative sagittal imbalance; psoas, erector spinae, and other balance parameters were not independently associated.

Practical implication: Better sagittal-balance maintenance was associated with larger paraspinal MI, reduced fat infiltration, and favorable preoperative LL/SL, supporting preoperative evaluation of muscle health, nutritional status, and alignment.

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Pedicle Subtraction Osteotomies for Surgical Correction of Fixed Sagittal Imbalance: A Meta-Analysis and Systematic Review

Neurosurgery 95:1223–1231, 2024

Disruption of the spine’s sagittal balance is associated with significant negative impacts on quality of life. Compared with other spinal osteotomies, pedicle subtraction osteotomy (PSO), which can potentially offer greater correction, is considered technically challenging and performed at lower rates. The aim of this study was to review the use of PSO to correct fixed sagittal imbalance and assess its efficacy and associated perioperative complications.

METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, EBSCO host, MEDLINE, and Google Scholar databases were queried for full-text English manuscripts published from 1961 to 2022, exploring PSO for the management of fixed sagittal imbalance. Studies were included if they reported preoperative and postoperative radiographic measurements. The mean Methodological Index for Nonrandomized Studies (MINORS) for included articles was 9.6 ± 1.1. The outcomes of interest included etiology, operative time, blood loss, complications, radiographic outcomes, and patient-reported outcomes. Statistical analysis was performed using a random-effects, inverse variance-weighted meta-analysis of observational data. Pre and postoperative radiographic and clinical outcomes were compared using a Student t-test.

RESULTS: Fourteen studies with 595 patients were included. Meta-analysis showed that the mean operative time was 7.2 ± 2.0 hours, and the average blood loss was 2033 ± 629 mL. After PSO, there was a significant improvement in sagittal vertebral axis (12.41-3.92 cm, P = .0003), LL (13.35°-42.60°, P = .000002), PSO angle (5.11°to À26.91°, P = .0001), and Oswestry Disability Index (55.36-27.35, P = .02). Common complications include pseudarthrosis (8.1%), neurological deficits (7.8%), and proximal junctional failure (6.0%).

CONCLUSION: PSO offers significant correction of sagittal vertebral axis, lumbar lordosis, PSO angle, and Oswestry Disability Index scores despite its reduced utilization in recent years. Blood loss and high complication rates must be considered when evaluating the efficacy of this procedure; however, surgeon experience and operative techniques can be used to reduce morbidity.

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Anterior Column Realignment: Analysis of Neurological Risk and Radiographic Outcomes

Neurosurgery DOI:10.1093/neuros/nyaa064

Anterior column realignment (ACR) is a less invasive alternative to 3-column osteotomy for the correction of sagittal imbalance. We hypothesized that ACR would correct sagittal imbalance with an acceptable neurological risk. OBJECTIVE: To assess long-term neurological and radiographic outcomes after ACR.

METHODS: Patients ≥18 yr who underwent ACR from 2005 to 2013 were eligible. Standing scoliosis radiographs were studied at preoperation, postoperation (≤6 wk), and at minimum 2 yr of follow-up. Clinical/radiographic data were collected through a retrospective chart review, with thoracic 1 spino-pelvic inclination (T1SPi) used as the angular surrogate for sagittal vertical axis.

RESULTS: A total of 26 patients had complete data, with a mean follow-up of 2.8 yr (1.8- 7.4). Preoperative, sagittal parameters were lumbar lordosis (LL) of −16.1◦, pelvic incidence (PI)-LL of 41.7◦, T1SPi of 3.6◦, and pelvis tilt (PT) of 32.4◦. LL improved by 30.6◦ (P < .001) postoperation.Mean changes in PT (−8.3), sacral slope (8.9), T1SPi (−4.9), and PI-LL (−33.5) were all significant. The motion segment angle improved by 26.6◦, from 5.2◦ to −21.4◦ (P < .001). Neurological complications occurred in 32% patients postoperation (n = 8; 1 patient with both sensory and motor). New thigh numbness/paresthesia developed in 3 (13%) patients postoperation; only 1 (4%) persisted at latest follow-up. A total of 6 (24%) patients developed a new lower extremity motor deficit postoperation,with 4 (8%) having persistent new weakness at last follow-up. Out of 8 patients with preoperative motor deficit, half saw improvement postoperation and 75% improved by last follow-up.

CONCLUSION: There was net motor improvement, with 24% of patients improving and 16% having persistent new weakness at latest follow-up; 60% were unchanged. Radiographic results demonstrate that ACR is a useful tool to treat severe sagittal plane deformity.

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Global Spinal Alignment in Cervical Kyphotic Deformity: The Importance of Head Position and Thoracolumbar Alignment in the Compensatory Mechanism

Neurosurgery 82:686–694, 2018

Previous studies have evaluated cervical kyphosis (C-kypho) using cervical curvature or chin-brow vertical angle, but the relationship between C-kypho and global spinal alignment is currently unknown.

OBJECTIVE: To elucidate global spinal alignment and compensatory mechanisms in primary symptomatic C-kypho using full-spine radiography.

METHODS: In this retrospectivemulticenter study, symptomatic primary C-kypho patients (Cerv group; n=103) and adult thoracolumbar deformity patients (TL group; n=119) were compared.We subanalyzed Cerv subgroups according to sagittal vertical axis (SVA) values of C7 (SVAC7 positive or negative [C7P or C7N]). Various Cobb angles (◦) and SVAs (mm) were evaluated.

RESULTS: SVAC7 values were –20.2 and 63.6 mm in the Cerv group and TL group, respectively (P < .0001). Various statistically significant compensatory curvatures were observed in the Cerv group, namely larger lumbar lordosis (LL) and thoracic kyphosis. The C7N group had significantly lower SVACOG (center of gravity of the head) and SVAC7 (32.9 and –49.5 mm) values than the C7P group (115.9 and 45.1 mm). Sagittal curvatures were also different in T4-12, T10-L2, LL4-S, and LL. The value of pelvic incidence (PI)-LL was different (C7N vs C7P; –2.2◦ vs 9.9◦; P < .0003). Compensatory sagittal curvatures were associated with potential for shifting of SVAC7 posteriorly to adjust head position. PI-LL affected these compensatory mechanisms. CONCLUSION: Compensation in symptomatic primary C-kypho was via posterior shifting of SVAC7, small T1 slope, and large LL. However, even in C-kypho patients, lumbar degeneration might affect global spinal alignment. Thus, global spinal alignment with cervical kyphosis is characterized as head balanced or trunk balanced.

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Design and Testing of 2 Novel Scores That Predict Global Sagittal Alignment Utilizing Cervical or Lumbar Plain Radiographs

Neurosurgery 82:163–171, 2018

Global sagittal deformity is an established cause of disability. However, measurements of sagittal alignment are often ignored when patients present with symptoms localizing to the cervical or lumbar spine.

OBJECTIVE: To develop scoring scales to predict the risk of sagittal malalignment in patients with only cervical or lumbar spine radiographs.

METHODS: A retrospective review of a prospectively maintained multicenter adult spinal deformity database was performed. Primary outcome (sagittal malalignment) was defined as a C7 plumbline ≥ 50 mm. Two multivariate logistic regressions were performed using patient characteristics and measurements derived from cervical or lumbar radiographs as covariates. Point scores were assigned to age, body mass index (BMI), and lumbar lordosis or T1 slope by rounding their ß coefficients to the nearest integer.

RESULTS: Nine hundred seventy-nine patients were included, with 652 randomly assigned to the derivation cohort (used to build the score) and 327 comprising the validation set. Final cervical score for the primary outcome included BMI ≥ 25 (1 point), age ≥ 55 yr (2 points), and T1 slope ≥ 27º (2 points). Final lumbar score for the primary outcome included BMI≥25 (1 point), age≥55 yr (1 point), and lumbar lordosis ≥45º (–1 points). High scores for both the cervical and lumbar spine presented with high specificity and positive likelihood ratios of sagittal malalignment.

CONCLUSION: We developed scoring scales to predict global sagittal malalignment utilizing clinical covariates and cervical or lumbar radiographs. Patients with high scores may prompt imaging with long-cassette plain films to evaluate for global sagittal imbalance.

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Pelvic retroversion: a compensatory mechanism for lumbar stenosis

J Neurosurg Spine 27:137–144, 2017

The flexed posture of the proximal (L1–3) or distal (L4–S1) lumbar spine increases the diameter of the spinal canal and neuroforamina and can relieve symptoms of neurogenic claudication. Distal lumbar flexion can result in pelvic retroversion; therefore, in cases of flexible sagittal imbalance, pelvic retroversion may be compensatory for lumbar stenosis and not solely compensatory for the sagittal imbalance as previously thought. The authors investigate underlying causes for pelvic retroversion in patients with flexible sagittal imbalance.

METHODS One hundred thirty-eight patients with sagittal imbalance who underwent a total of 148 fusion procedures of the thoracolumbar spine were identified from a prospective clinical database. Radiographic parameters were obtained from images preoperatively, intraoperatively, and at 6-month and 2-year follow-up. A cohort of 24 patients with flexible sagittal imbalance was identified and individually matched with a control cohort of 23 patients with fixed deformities. Flexible deformities were defined as a 10° change in lumbar lordosis between weight-bearing and non–weight-bearing images. Pelvic retroversion was quantified as the ratio of pelvic tilt (PT) to pelvic incidence (PI).

RESULTS The average difference between lumbar lordosis on supine MR images and standing radiographs was 15° in the flexible cohort. Sixty-eight percent of the patients in the flexible cohort were diagnosed preoperatively with lumbar stenosis compared with only 22% in the fixed sagittal imbalance cohort (p = 0.0032). There was no difference between the flexible and fixed cohorts with regard to C-2 sagittal vertical axis (SVA) (p = 0.95) or C-7 SVA (p = 0.43). When assessing for postural compensation by pelvic retroversion in the stenotic patients and nonstenotic patients, the PT/PI ratio was found to be significantly greater in the patients with stenosis (p = 0.019).

CONCLUSIONS For flexible sagittal imbalance, preoperative attention should be given to the root cause of the sagittal misalignment, which could be compensation for lumbar stenosis. Pelvic retroversion can be compensatory for both the lumbar stenosis as well as for sagittal imbalance.

 

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Surgical treatment of pathological loss of lumbar lordosis (flatback)

Flatback

J Neurosurg Spine 21:160–170, 2014

Increased sagittal vertical axis (SVA) correlates strongly with pain and disability for adults with spinal deformity. A subset of patients with sagittal spinopelvic malalignment (SSM) have flatback deformity (pelvic incidence–lumbar lordosis [PI-LL] mismatch > 10°) but remain sagittally compensated with normal SVA. Few data exist for SSM patients with flatback deformity and normal SVA. The authors’ objective was to compare baseline disability and treatment outcomes for patients with compensated (SVA < 5 cm and PI-LL mismatch > 10°) and decompensated (SVA > 5 cm) SSM.

Methods. The study was a multicenter, prospective analysis of adults with spinal deformity who consecutively underwent surgical treatment for SSM. Inclusion criteria included age older than 18 years, presence of adult spinal deformity with SSM, plan for surgical treatment, and minimum 1-year follow-up data. Patients with SSM were divided into 2 groups: those with compensated SSM (SVA < 5 cm and PI-LL mismatch > 10°) and those with decompensated SSM (SVA ≥ 5 cm). Baseline and 1-year follow-up radiographic and health-related quality of life (HRQOL) outcomes included Oswestry Disability Index, Short Form–36 scores, and Scoliosis Research Society–22 scores. Percentages of patients achieving minimal clinically important difference (MCID) were also assessed.

Results. A total of 125 patients (27 compensated and 98 decompensated) met inclusion criteria. Compared with patients in the compensated group, patients in the decompensated group were older (62.9 vs 55.1 years; p = 0.004) and had less scoliosis (43° vs 54°; p = 0.002), greater SVA (12.0 cm vs 1.7 cm; p < 0.001), greater PI-LL mismatch (26° vs 20°; p = 0.013), and poorer HRQOL scores (Oswestry Disability Index, Short Form-36 physical component score, Scoliosis Research Society-22 total; p ≤ 0.016). Although these baseline HRQOL differences between the groups reached statistical significance, only the mean difference in Short Form–36 physical component score reached threshold for MCID. Compared with baseline assessment, at 1 year after surgery improvement was noted for patients in both groups for mean SVA (compensated –1.1 cm, decompensated +4.8 cm; p ≤ 0.009), mean PI-LL mismatch (compensated 6°, decompensated 5°; p < 0.001), and all HRQOL measures assessed (p ≤ 0.005). No significant differences were found between the compensated and decompensated groups in the magnitude of HRQOL score improvement or in the percentages of patients achieving MCID for each of the outcome measures assessed.

Conclusions. Decompensated SSM patients with elevated SVA experience significant disability; however, the amount of disability in compensated SSM patients with flatback deformity caused by PI-LL mismatch but normal SVA is underappreciated. Surgical correction of SSM demonstrated similar radiographic and HRQOL score improvements for patients in both groups. Evaluation of SSM should extend beyond measuring SVA. Among patients with concordant pain and disability, PI-LL mismatch must be evaluated for SSM patients and can be considered a primary indication for surgery.

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Risk Factors of Sagittal Decompensation After Long Posterior Instrumentation and Fusion for Degenerative Lumbar Scoliosis

SPINE Volume 35, Number 17, pp 1595–1601.

Study Design. A retrospective study of clinical results of operative treatment for degenerative lumbar scoliosis.

Objective. To determine the risk factors of sagittal decompensation after long instrumentation and fusion to L5 or S1. Summary of Background Data. Little is known about the risk factors for sagittal decompensation, which was defined in this study as sagittal C7 plumb falling anterior 8 cm from the posterosuperior corner of the sacrum.

Methods. Forty-five patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were reviewed retrospectively with a minimum 2 years. The mean number of levels fused was 6.1  1.6 segments. The upper instrumented vertebra ranged from T9 to L2. The lower instrumented vertebra was L5 and S1 in 24 and 21 patients, respectively.

Results. Sagittal decompensation (SD) developed in 19 patients. The most significant risk factors of SD were preoperative sagittal imbalance and high pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm) in the decompensation group than in the balance group (37.0 mm) (P = 0.002). There was a significant difference in pelvic incidence between 61.7° in the decompensation and 54.9° in the balance group (P = 0.01). The preoperative lumbar lordosis was hypolordotic in the decompensation group, however, it was not found to be a risk factor. Pseudarthrosis was identified at the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed in 55% of patients who had loosening of the distal screws and 50% of patients with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely to cause SD than proximal adjacent segment disease.

Conclusion. Sagittal decompensation is common after long posterior instrumentation and fusion for degenerative lumbar scoliosis. It is mostly associated with complications at the distal segments, including pseudarthrosis and implant failure at the lumbosacral junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation is necessary especially in patients with preoperative sagittal imbalance and high pelvic incidence in order to prevent sagittal decompensation after surgery. Key words: adult spinal deformity, degenerative lumbar scoliosis, sagittal imbalance, sagittal decompensation, risk factor

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