Analysis of the Dynamic Sagittal Balance of the Lumbo-Pelvi-Femoral Complex

In the anatomy of a normal spine, due to the curvatures in various regions, the C7 plumb line (C7PL) passes through the sacrum so that the head is centered over the pelvic-ball and socket hip and ankle joints. A failure to recognize malalignment in the sagittal plane can affect the patient's activity as well as social interaction due to deficient forward gaze. The sagittal balance configuration leads to the body undertaking the least muscular activities as possible necessary to maintain spinal balance. Global sagittal imbalance is energy consuming and often results in painful compensatory mechanisms that in turn negatively influence the patient's quality of life, self-image, and social interaction due to inability to maintain a horizontal gaze. Deformity, scoliosis, kyphosis, trauma, and/or surgery are some ways that this optimal configuration can be disturbed, thus requiring higher muscular activity to maintain posture and balance. Several parameters such as the thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and hip and leg positions influence the sagittal balance and thus the optimal configuration of spinal alignment. This review examines the clinical and biomechanical aspects of spinal imbalance, and the biomechanics of spinal balance as dictated by deformities—ankylosing spondylitis (AS), scoliosis and kyphosis; surgical corrections—pedicle subtraction osteotomies (PSO), long segment stabilizations, and consequent postural complications like proximal and distal junctional kyphosis. The study of the biomechanics involved in spinal imbalance is relatively new and thus the literature is rather sparse. This review suggests several potential research topics in the area of spinal biomechanics.

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Stand-Alone Posterior Expandable Cage Technique for Adjacent Segment Degeneration with Lumbar Spinal Canal Stenosis: A Retrospective Case Series

Medicina ◽

10.3390/medicina57030237 ◽

2021 ◽

Vol 57 (3) ◽

pp. 237

Author(s):

Woo-Jin Choi ◽

Seung-Kook Kim ◽

Manhal Alaraj ◽

Hyeun-Sung Kim ◽

Su-Chan Lee

Keyword(s):

Sagittal Balance ◽

Spinal Canal ◽

Interbody Fusion ◽

Adjacent Segment Degeneration ◽

Spinal Canal Stenosis ◽

Adjacent Segment ◽

Lumbar Spinal Canal Stenosis ◽

Canal Stenosis ◽

Lumbar Spinal ◽

Expandable Cages

Background and Objectives: Symptomatic adjacent segment degeneration (ASD) with lumbar spinal canal stenosis (LSCS) is a common complication after spinal intervention, particularly interbody fusion. Stand-alone posterior expandable cages enable interbody fusion with preservation of the previous operation site, and screw-related complications are avoided. Thus, the aim of this study was to investigate the clinicoradiologic outcomes of stand-alone posterior expandable cages for ASD with LSCS. Materials and Methods: Patients with persistent neurologic symptoms and radiologically confirmed ASD with LSCS were evaluated between January 2011 and December 2016. The five-year follow-up data were used to evaluate the long-term outcomes. The radiologic parameters for sagittal balance, pain control (visual analogue scale), disability (Oswestry Disability Index), and early (peri-operative) and late (implant) complications were evaluated. Results: The data of 19 patients with stand-alone posterior expandable cages were evaluated. Local factors, such as intervertebral and foraminal heights, were significantly corrected (p < 0.01 and p < 0.01, respectively), and revision was not reported. The pain level (p < 0.01) and disability rate (p < 0.01) significantly improved, and the early complication rate was low (n = 2, 10.52%). However, lumbar lordosis (p = 0.62) and sagittal balance (p = 0.80) did not significantly improve. Furthermore, the rates of subsidence (n = 4, 21.05%) and retropulsion (n = 3, 15.79%) were high. Conclusions: A stand-alone expandable cage technique should only be considered for older adults and patients with previous extensive fusion. Although this technique is less invasive, improves the local radiologic factors, and yields favorable clinical outcomes with low revision rates, it does not improve the sagittal balance. For more widespread application, the strength of the cage material and high subsidence rates should be improved.

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Lumbar Level Significantly Influences Postoperative Global Sagittal Balance Following Pedicle Subtraction Osteotomy

Global Spine Journal ◽

10.1177/21925682211032563 ◽

2021 ◽

pp. 219256822110325

Author(s):

Athan G. Zavras ◽

T. Barrett Sullivan ◽

Navya Dandu ◽

Howard S. An ◽

Christopher J. DeWald ◽

...

Keyword(s):

Sagittal Balance ◽

Sagittal Alignment ◽

Adult Spinal Deformity ◽

Vertical Axis ◽

Pedicle Subtraction Osteotomy ◽

Current Evidence ◽

Sacral Slope ◽

Sagittal Vertical Axis ◽

Lumbar Level ◽

Global Sagittal Alignment

Study Design: Retrospective cohort study. Objectives: The current evidence regarding how level of lumbar pedicle subtraction osteotomy (PSO) influences correction of sagittal alignment is limited. This study sought to investigate the relationship of lumbar level and segmental angular change (SAC) of PSO with the magnitude of global sagittal alignment correction. Methods: This study retrospectively evaluated 53 consecutive patients with adult spinal deformity who underwent lumbar PSO at a single institution. Radiographs were evaluated to quantify the effect of PSO on lumbar lordosis (LL), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), T1-spinopelvic inclination (T1SPI), T1-pelvic alignment (TPA), and sagittal vertical axis (SVA). Results: Significant correlations were found between PSO SAC and the postoperative increase in LL ( r = 0.316, P = .021) and PT ( r = 0.352, P = .010), and a decrease in TPA ( r = −0.324, P = .018). PSO level significantly correlated with change in T1SPI ( r = −0.305, P = .026) and SVA ( r = −0.406, P = .002), with more caudal PSO corresponding to a greater correction in sagittal balance. On multivariate analysis, more caudal PSO level independently predicted a greater reduction in T1SPI (β = −3.138, P = .009) and SVA (β = −29.030, P = .001), while larger PSO SAC (β = −0.375, P = .045) and a greater number of fusion levels (β = −1.427, P = .036) predicted a greater reduction in TPA. Conclusion: This study identified a gain of approximately 3 degrees and 3 cm of correction for each level of PSO more caudal to L1. Additionally, a larger PSO SAC predicted greater improvement in TPA. While further investigation of these relationships is warranted, these findings may help guide preoperative PSO level selection.

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A Novel Perspective for Analyzing Craniocervical Sagittal Balance and Horizontal Gaze

World Neurosurgery ◽

10.1016/j.wneu.2021.01.077 ◽

2021 ◽

Author(s):

Aydin Gerilmez ◽

Sait Naderi

Keyword(s):

Sagittal Balance ◽

Horizontal Gaze

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Assessment of Normal Sagittal Alignment of the Spine and Pelvis in Children and Adolescents

BioMed Research International ◽

10.1155/2013/842624 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 14

Author(s):

Hasan Ghandhari ◽

Hamid Hesarikia ◽

Ebrahim Ameri ◽

Abolfazl Noori

Keyword(s):

Children And Adolescents ◽

Sagittal Balance ◽

Sagittal Alignment ◽

Demographic Data ◽

Lateral View ◽

Old People ◽

Spinopelvic Parameters ◽

Spinopelvic Balance ◽

History Of ◽

Data History

Aim. We aimed to determine spinopelvic balance in 8–19-year-old-people in order to assess pelvic and spinal parameters in sagittal view.Methods. Ninety-eight healthy students aged 8–19 years, who lived in the central parts of Tehran, were assessed. Demographic data, history of present and past diseases, height (cm), and weight (kg) were collected. Each subject was examined by an orthopedic surgeon and spinal radiographs in lateral view were obtained. Eight spinopelvic parameters were measured by 2 orthopedic spine surgeons.Results. Ninety-eight subjects, among which 48 were girls (49%) and 50 boys (51%), with a mean age of13.6±2.9years (range: 8–19) were evaluated. Mean height and weight of children were153.6±15.6cm and49.9±13.1kgs, respectively. Mean TK, LL, TT, LT, and PI of subjects were 37.1 ± 9.9°, 39.6 ± 12.4°, 7.08 ± 4.9°, 12.0 ± 5.9°, and 45.37 ± 10.7°, respectively.Conclusion. Preoperation planning for spinal fusion surgeries via applying PI seems reasonable. Predicating “abnormal” to lordosis and kyphosis values alone without considering overall sagittal balance is incorrect. Mean of SS and TK in our population is slightly less than that in Caucasians.

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