Review

Authors: Kariman Abelin-Genevois

Spinal balance can be defined as the trade-off between outside forces acting on the spine and the muscle response of the trunk, under sensorineural regulation, to maintain stable upright posture, both static and dynamic. Homo sapiens developed sagittal alignment along with bipedalism. The upright posture was an important step in human evolution, to master the environment, at the price of some instability in postural control in the trunk, and to maintain horizontal gaze. To make upright stance energetically economical and thus sustainable, reciprocal sagittal curvatures developed. Sagittal spinal organization is governed by strict rules under physiological conditions, enabling alignment between the center of mass and the lower limb joint centers. In children and adolescents, morphologic changes related to skeletal growth and postural control centers maturation alter spinal alignment and hence spinal balance, with increases in pelvic incidence, sacral slope and consequently lumbar lordosis and thoracic kyphosis. Global cervical lordosis remains stable, at the cost of an increase of the inferior cervical lordosis angle in correlation with T1 inclination or T1 slope. In pathology, spinal alignment may induce certain spinal pathologies such as growth-related spinal dystrophy or spondylolisthesis. It can also be altered by spinal deformity such as scoliosis, a regional disorder inducing adjacent compensatory mechanisms. The management of spinal pathologies is indissociable from understanding and maintaining or restoring individual sagittal alignment so as to ensure physiological distribution of stresses and limit onset of complications or decompensation in adulthood.

Topics: Adolescent; Adult; Child; Humans; Kyphosis; Lordosis; Posture; Sacrum; Scoliosis; Spine

PubMed: 33321235
DOI: 10.1016/j.otsr.2020.102769

Review

Authors: Dariusz Czaprowski, Łukasz Stoliński, Marcin Tyrakowski...

BACKGROUND

The physiological sagittal spinal curvature represents a typical feature of good body posture in the sagittal plane. The cervical and the lumbar spine are curved anteriorly (lordosis), while the thoracic segment is curved posteriorly (kyphosis). The pelvis is inclined anteriorly, and the lower limbs' joints remain in a neutral position. However, there are many deviations from the optimal body alignment.The aim of this paper is to present the most common types of non-structural misalignments of the body posture in the sagittal plane.

MAIN BODY OF THE ABSTRACT

The most common types of non-structural misalignments of body posture in the sagittal plane are as follows: (1) lordotic, (2) kyphotic, (3) flat-back, and (4) sway-back postures. Each one may influence both the skeletal and the muscular system leading to the functional disturbance and an increased strain of the supporting structures. Usually, the disturbances localized within the muscles are analyzed in respect to their shortening or lengthening. However, according to suggestions presented in the literature, when the muscles responsible for maintaining good body posture (the so-called stabilizers) are not being stimulated to resist against gravity for an extended period of time, e.g., during prolonged sitting, their stabilizing function is disturbed by the hypoactivity reaction resulting in muscular weakness. The deficit of the locomotor system stability triggers a compensatory mechanism-the stabilizing function is overtaken by the so-called mobilizing muscles. However, as a side effect, such compensation leads to the increased activity of mobilizers (hyperactivity) and decreased flexibility, which may finally lead to the pathological chain of reaction within the musculoskeletal system.

CONCLUSIONS

There exist four principal types of non-structural body posture misalignments in the sagittal plane: lordotic posture, kyphotic posture, flat-back posture, and sway-back posture. Each of them can disturb the physiological loading of the musculoskeletal system in a specific way, which may lead to a functional disorder.When planning postural corrective exercises, not only the analysis of muscles in respect to their shortening and lengthening but also their hypoactivity and hyperactivity should be considered.

PubMed: 29516039
DOI: 10.1186/s13013-018-0151-5

Authors: Ibrahim Obeid, Pedro Berjano, Claudio Lamartina...

INTRODUCTION

In adult spinal deformity (ASD), sagittal imbalance and sagittal malalignment have been extensively described in the literature during the past decade, whereas coronal imbalance and coronal malalignment (CM) have been given little attention. CM can cause severe impairment in adult scoliosis and ASD patients, as compensatory mechanisms are limited. The aim of this paper is to develop a comprehensive classification of coronal spinopelvic malalignment and to suggest a treatment algorithm for this condition.

METHODS

This is an expert's opinion consensus based on a retrospective review of CM cases where different patterns of CM were identified, in addition to treatment modifiers. After the identification of the subgroups for each category, surgical planning for each subgroup could be specified.

RESULTS

Two main CM patterns were defined: concave CM (type 1) and convex CM (type 2), and the following modifiers were identified as potentially influencing the choice of surgical strategy: stiffness of the main coronal curve, coronal mobility of the lumbosacral junction and degeneration of the lumbosacral junction. A surgical algorithm was proposed to deal with each situation combining the different patterns and their modifiers.

CONCLUSION

Coronal malalignment is a frequent condition, usually associated to sagittal malalignment, but it is often misunderstood. Its classification should help the spine surgeon to better understand the full spinal alignment of ASD patients. In concave CM, the correction should be obtained at the apex of the main curve. In convex CM, the correction should be obtained at the lumbosacral junction. These slides can be retrieved under Electronic Supplementary Material.

Topics: Humans; Practice Guidelines as Topic; Retrospective Studies; Scoliosis; Spine

PubMed: 30460601
DOI: 10.1007/s00586-018-5826-3

Authors: Amir A Amanullah, Taemin Oh, Brandon J Toll...

This study investigated risk factors for progression of deformity in pediatric congenital cervical scoliosis (CCS) and evaluated the correlation between congenital cervical curves and compensatory thoracic and lumbar curves. Medical records were retrospectively reviewed for 38 pediatric patients with CCS with a minimum 2-year follow-up. Curve progression was defined as >10° increase in cervical coronal curve angle between presentation and last follow-up. A total of 38 patients (16 girls, 22 boys) with a mean age at presentation of 5.6 ± 4.1 years met the inclusion criteria. Sixteen patients (42%) had curve progression with a mean follow-up of 3.1 ± 3.0 years. At presentation, T1 slope was significantly larger among children with progressive deformities ( = 0.041). A total of 18 of the 38 patients with strictly cervical spine deformity were then selected for subanalysis to evaluate the progression of compensatory curves. Cervical major coronal curves were found to significantly correlate with lumbar major coronal curves (r = 0.409), C2 central sacral vertical line (CSVL) (r = 0.407), and C7-CSVL (r = 0.403) ( < 0.05). Thoracic major coronal curves did not significantly correlate with cervical major coronal curves (r = 0.218) ( > 0.05). In conclusion, 42% of osseous CCS curves progressed over time in the overall cohort, and high initial T1 slope was found to be most highly correlated with progression of cervical deformity. Cervical major coronal curves significantly correlated with lumbar curve magnitude but not with thoracic curve size in isolated CCS, possibly due to the increased flexibility of the lumbar spine which may allow greater compensatory balance and thus have a greater correlation with cervical curve magnitude and possibly progression.

PubMed: 38892749
DOI: 10.3390/jcm13113039

Authors: Tom P C Schlösser, Marijn van Stralen, Winnie C W Chu...

INTRODUCTION

Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before.

METHODS

A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between.

RESULTS

The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves).

CONCLUSIONS

Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the compensatory curves, the junctional zones do not exhibit this growth discrepancy, however, they are straight.

Topics: Adolescent; Adult; Case-Control Studies; Female; Humans; Imaging, Three-Dimensional; Male; Scoliosis; Tomography, X-Ray Computed

PubMed: 27467745
DOI: 10.1371/journal.pone.0160267

Authors: Dongfan Wang, Wei Wang, Yu Wang...

BACKGROUND CONTEXT

Previous research has identified a specific subtype known as failure of pelvic compensation (FPC) in patients with adult spinal deformity (ASD). However, the criteria for assessing FPC remain inconsistent, and its impacts on spinal sagittal alignment and health-related quality-of-life (HRQoL) scores remain unclear.

PURPOSE

To propose a novel criterion for identifying FPC based on variations in spinopelvic alignment during the transition from the supine to upright position and to evaluate the effects of FPC on patients' spinal sagittal alignment and HRQoL scores.

STUDY DESIGN/SETTING

Retrospective cross-sectional study.

PATIENT SAMPLE

Patients with ASD from a monocenter database.

OUTCOME MEASURES

Radiographic measures, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt, pelvic incidence (PI), and sagittal vertical axis (SVA), were measured on lateral whole-spine radiographs. LL and SS were also measured on reconstructed lumbar computed tomography images in the sagittal view taken in the supine position. The relative functional cross-sectional area (rFCSA) of paraspinal muscles was evaluated via lumbar magnetic resonance imaging. HRQoL measures, encompassing visual analog scale for back pain (VAS-BP), Oswestry Disability Index (ODI), and Scoliosis Research Society-22R (SRS-22R), were collected.

METHODS

A total of 154 patients were enrolled. Based on the calculated minimum detectable change of SS, FPC was defined as the change in SS of less than 3.4° between supine and upright positions. Patients were divided into 3 groups: sagittal balance with pelvic compensation (SI-PC), sagittal imbalance with pelvic compensation (SI-PC), and sagittal imbalance with failure of pelvic compensation (SI-FPC). Radiographic parameters and HRQoL scores were compared among the groups.

RESULTS

Thirty-six patients were categorized into the SB-PC group, 87 into the SI-PC group, and 31 into the SI-FPC group. Patients with low PI and small paraspinal muscles rFCSA were more prone to experiencing FPC accompanied by severe sagittal imbalance. The SI-FPC group exhibited less TK and a larger SS than the SI-PC group exhibited and had a similar SVA as that of the SI-PC group. Additionally, they displayed worse VAS-BP, ODI, SRS-function, and SRS-22 total scores than the SB-PC group displayed.

CONCLUSIONS

In patients with ASD, an inherently low pelvic compensatory reserve and a high fatty infiltration in paraspinal muscles are pivotal factors contributing to FPC. Compared with SI-PC patients, SI-FPC patients demonstrate a thoracic-dominant compensatory pattern for sagittal malalignment. In addition, these patients experienced more severe pain and functional decline than the SB-PC patients experienced.

Topics: Humans; Male; Female; Middle Aged; Retrospective Studies; Quality of Life; Aged; Cross-Sectional Studies; Adult; Pelvis; Lordosis; Kyphosis

PubMed: 38925300
DOI: 10.1016/j.spinee.2024.06.011

Authors: Kenneth Aaron Shaw, Joshua S Murphy

PubMed: 31032453
DOI: 10.21037/jss.2019.01.01

Authors: Aurélien Courvoisier, Alice Baroncini, Clément Jeandel...

Vertebral Body Tethering (VBT) is a recently developed surgical technique for the treatment of progressive and severe scoliosis in patients with significant growth potential. It has been used since the first exploratory series, which showed encouraging results on the progressive correction of the major curves. This study reports on a retrospective series of 85 patients extracted from a French cohort, with a follow-up at a minimum of two years after a VBT with recent screws-and-tether constructs. The major and compensatory curves were measured pre-operatively, at the 1st standing X-ray, at 1 year, and at the last available follow-up. The complications were also analyzed. A significant improvement was observed in the curve magnitude after surgery. Thanks to growth modulation, both the main and the secondary curves continued to progress over time. Both the thoracic kyphosis and lumbar lordosis remained stable over time. Overcorrection occurred in 11% of the cases. Tether breakage was observed in 2% of the cases and pulmonary complications in 3% of the cases. VBT is an effective technique for the management of adolescent idiopathic scoliosis patients with residual growth potential. VBT opens an era of a more subtle and patient-specific surgical management of AIS that considers parameters such as flexibility and growth.

PubMed: 36832321
DOI: 10.3390/children10020192

Authors: J Manuel Sarmiento, Mitchell S Fourman, Han Jo Kim...

BACKGROUND

There is a continued trend toward posterior-only approaches for achieving spinal deformity correction of idiopathic scoliosis. We present a posteriorly based correction technique and en bloc translation reduction maneuver that can be useful in the management of kyphoscoliosis.

OBSERVATIONS

A 50-year-old female with a past medical history of untreated adolescent idiopathic scoliosis since she was 12 years old presented to the clinic for evaluation of progressive thoracolumbar spinal deformity and worsening mid-to-low back pain. Standing scoliosis radiographs shows an 85° left lumbar curve with an apex at the L1-2 disk. There was a compensatory 58° right thoracic curve with an apex at T9, a -1.4 cm central vertical axis, and a focal kyphotic deformity of 86° from T11-L3 with a corresponding apex at the L1-2 disk. She was diagnosed with adult idiopathic scoliosis and indicated for a T9-L4 posterior spinal fusion with T11-L4 Smith-Peterson osteotomies. A simple en bloc reduction maneuver was used to translate the apex of the coronal deformity toward the midline and simultaneously correct the patient's focal kyphosis.

LESSONS

A construct-to-construct biplanar cantilever technique is ideal for the treatment of kyphoscoliosis and can provide effective deformity correction in both the sagittal and coronal planes.

PubMed: 37039296
DOI: 10.3171/CASE22527

Review

Authors: Saverio Colonna, Fabio Casacci, Corrado Borghi...

In subjects with scoliotic alterations of the spine, asymmetrical lengths of the lower limbs are frequently observed, a condition commonly referred to as leg length inequality (LLI) or discrepancy (LLD). This asymmetry can induce pelvic misalignments, manifested by an asymmetric height of the iliac crests, and consequently an alteration of the spine's axis. Although correcting this discrepancy might appear to be a straightforward solution, further investigation may reveal other indications. The purpose of this article is to aid clinicians confronted with the decision of whether to compensate for an LLI in individuals with scoliosis, encompassing both adolescents and adults. It presents a literature review on the incidence of LLIs in the general population, distinguishing between structural LLI (sLLI) and functional LLI (fLLI) types of LLIs, and quantifying their magnitude with clinical and instrumental evaluation. Additionally, it links these two types of LLIs to the type of scoliosis (structural or functional). From a clinical perspective, it also examines the compensatory mechanisms employed by the pelvis in the presence of structural or functional LLIs in order to draw useful indications for therapeutic decisions. Moreover, it proposes an additional evaluation parameter in the coronal plane, namely the central sacral vertical line (CSVL), to aid in the decision-making process regarding LLI compensation. Although this parameter has been documented in the literature, it has been little associated with LLIs. The findings indicate that scoliotic discrepancies should be compensated (conservatively or surgically) only when the imbalance of the femoral heads is on the same side as the imbalance of the sacrum and the iliac crests; this corrective action should result in a reduction of the overhang in the coronal plane.

PubMed: 38633141
DOI: 10.7759/cureus.58443