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49 De Novo Deformity

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49.4 Imaging

Although the lumbar spine is typically involved, the standard radiographic examination should consist of whole spine 36-inch long-cassette standing radiographs in the anteroposterior and lateral views (Fig.49.2). This allows an accurate assessment of the true magnitude of the coronal deformity, presence of lateral subluxation of the

Fig. 49.2 Anteroposterior (AP) and lateral (Lat) long-cassette radiogram of a de novo deformity. The patient has a lateral subluxation of the apical vertebra and osteophytes around the apex in the AP view. The Lat view shows a lumbar kyphosis due to axial rotation. This mechanism is demonstrated with an animation in Fig.49.1

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Pelvic Incidenc

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K. Y. H. Kwan and K. M. C. Cheung

Sagittal Vertical

Axis

(SVA)

(PI)

Fig. 49.3 Sagittal and spinopelvic parameters which can be used in deformity analysis and preoperative planning

Pelvic Tilt

(PT)

Sacral Slope

(ss)

vertebra, and tilting of the lower lumbar vertebrae and pelvis (Video 49.6). On the lateral view, both femoral heads should be included in the lm to allow the determination of the pelvic incidence. In addition, regional and global sagittal balance parameters can be determined (Fig.49.3). Using these parameters, these deformities can be classied using the Aebi classication or the now more commonly used SRS-Schwab classication (Fig.49.4) (Chap. 50).

In instances where the anatomy is not very clear on plain radiographs, computed tomography can be requested. In patients where the status of the disc and the spinal canal needs to be visualized, magnetic resonance imaging should be obtained.

49.5 Differential Diagnosis

Curve patterns and locations may indicate if the deformity is due to neglected adolescent idiopathic scoliosis, and they will often present younger than the de novo curves. Other diagnoses of spinal deformities such as neuromuscular, syndromal,

Coronal Curve Types Sagittal Modifiers

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T: Thoracic only

with lumber curve < 30°

L: TL / Lumbar only

with thoracic curve <30°

D: Double Curve

with T and TL/L curves > 30°

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Pl minus LL

0 : within 10°

+ : moderate 10-20°

++ : marked >20°

Global Alignment

0 : SVA < 4cm

+ : SVA 4 to 9.5cm

++ : SVA > 9.5cm

N: No Major Coronal Deformity

all coronal curves <30°

Fig. 49.4 SRS-Schwab classication for the adult deformity

Pelvic Tilt

0 : PT<20°

+ : PT 20-30°

++ : PT>30°

traumatic, and congenital should be obvious from the patient’s history and physical examination.

49.6 Treatment Options

De novo deformity of the spine per se in adulthood does not require surgical correction if the patient is completely asymptomatic. Hence, a comprehensive clinical history including the chief complaints, functional limitation, and presence of neurologic decit is key in determining the treatment regimen. It is established that coronal deformity and imbalance are better tolerated to a certain degree than sagittal imbalance.

Nonoperative treatment includes pharmacotherapy, lifestyle modications, isometric core, and back muscle strengthening exercises that have their roles in alleviating patients’ symptoms and improving quality of life. The use of brace preceded by plaster cast to test correction (of lumbar kyphosis, in particular) may work sufciently well to avoid surgical treatment in some cases. Nonetheless, most research has shown that patients with severe sagittal imbalance do not improve with conservative care.

Diagnostic nerve root and facet joint blockades are useful adjuncts in the decision- making of complex de novo deformity, where the pain generators are not immediately obvious from the clinical history or physical examination. It allows the

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surgeon to determine the goals of any surgical intervention that is required and, at the same time, can give the patients some temporary relief to maximize the efforts of conservative care.

The aims of any surgical interventions are to improve patients’ quality of life by decompression of neural elements, stabilization of spinal segments, and correction of spinal deformities in the coronal and sagittal planes (Videos 49.2, 49.3, 49.7 and

49.10). However, the alignment goals, particularly of the sagittal plane, are still under intensive investigation. Both the SRS-Schwab (Fig. 49.4) and Roussouly/ Global Alignment and Proportion (GAP; it evaluates the following parameters: (a) sacral slope, (b) L1–S1 lordosis, (c) L4–S1 lordosis, and (d) global tilt) classications give some guidance on the degree of deformity correction is needed, but longterm results are difcult to assess due to the heterogeneity of this patient population (Chap. 50). Preoperative dual-energy radiograph absorptiometry should be obtained to assess the bone mineral density.

K. Y. H. Kwan and K. M. C. Cheung

49.7 Expected Outcomes

For patients with signicant limitations in the quality of life with progressive deformity, nonoperative treatment with standard conservative care has not shown to be effective although brace treatment may provide pain control during daytime. Surgical correction in this group of patients leads to signicant improvements in their quality of life, which also applies to patients who suffer from postoperative complications and unplanned return to the operating theaters. However, potential surgical candidates should be made aware of the high complication prole of such procedures (both neurologic and non-neurologic events) during the shared decisionmaking process.

49.8 Potential Complications

It should be noted that many patients will not suffer from any degree of functional limitation and will not experience any complications. Nonetheless, untreated de novo scoliosis may result in curve progression, neurologic decit, pain, and limitation in functional activities.

49.9 What Patient andFamily Should Know?

De novo scoliosis may be an incidental nding or the cause of back pain and functional limitation in the adult population. Treatment options depend on patients’ symptoms and neurologic status. Although surgical interventions carry high complication rates, most studies suggest a signicant improvement in the quality of life and a high rate of patient satisfaction.

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Further Readings

Faraj SSA, Holewijn RM, van Hoff ML, etal. De novo degenerative lumbar scoliosis: a systematic

review of prognostic factors for curve progression. Eur Spine J. 2016;25(8):2347–58. Faraj SSA, Haanstra T, Martijn H, etal. Functional outcome of non-surgical and surgical manage-

ment for de novo degenerative lumbar scoliosis: a mean follow-up of 10years. Scoliosis Spinal

Disord. 2017;12:35. Simon MJK, Halm HFH, Quante M.Perioperative complications after surgical treatment in degen-

erative adult de novo scoliosis. BMC Musculoskelet Disord. 2018;19(1):10.

Sagittal Plane Malalignment

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CaglarYilgor, AltugYucekul, andAhmetAlanay

50.1 Definition

While the spine, in the ideal standing posture, is straight in the frontal plane, it has various physiological curvatures in the sagittal plane such as cervical lordosis, thoracic kyphosis, and lumbar lordosis. The magnitude and location of these curvatures differ from one person to another (Video 50.6). Sagittal plane malalignment refers to the condition where the magnitude and/or shape of these curvatures has deviated from the normal range of values. A range of pathologies may lead to sagittal malalignments such as scoliosis (Chap. 16), spondylolisthesis (Chap. 25), degenerative disease (Chap. 47), and iatrogenic at back.

50.2 Natural History

Once bones, joints, discs, and ligaments lose their anatomical and physiological qualities via trauma, various spinal diseases, and through the normal aging process, spinopelvic alignment begins to deteriorate. The natural evolution of the sagittal plane is increased kyphosis, loss of lordosis, pelvic retroversion, and

Supplementary Information The online version contains supplementary material available at [https://doi.org/10.1007/978- 3- 030- 80356- 8_50].

C. Yilgor · A. Yucekul · A. Alanay (*) Department of Orthopedics and Traumatology, Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, Turkey

https://doi.org/10.1007/978-3-030-80356-8_50

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positive global tilt. Yet, human beings, through subconscious mechanisms, have a tendency (1) to stand in the most ergonomic position that leads to the lowest energy consumption while standing and walking, (2) to position their heads over the pelvis, and (3) to maintain a forward gaze. In cases where the spine deviates from this “ideal” ergonomic, so-called compensatory mechanisms are activated. These mechanisms use “reserves” located in the spine and in non-spinal body segments (particularly legs) in order to maintain the upright posture. The use of these reserves requires active muscle contraction and increases energy consumption related to mobilization.

C. Yilgor et al.

50.3 Treatment Options

Today, there are three comprehensive analysis models based on different approaches: the SRS-Schwab criteria focusing on the clinical impact, the Roussouly back types based on shapes and biomechanics, and the Global Alignment and Proportion (GAP) score using a PI-adjusted mathematical approach.

50.3.1 SRS-Schwab Classification

The criteria for the SRS-Schwab classication are pelvic tilt (PT), pelvic incidence (PI) minus lumbar lordosis (PI–LL), and sagittal vertical axis (SVA) [1]. Measured values are categorized as normal, moderate, and severe. For these three criteria, target values are SVA <5 mm, PT <25o, and PI-LL ±9o. It has the advantages of relating to patient-reported outcomes and ease of use. Conversely, disadvantages include the absence of anteversion, negative alignment and distribution of lordosis, and the position-dependent nature of the use of SVA.More importantly, these target values have been determined by considering population-based averages and are the same for all individuals.

50.3.2 Roussouly Back Types

Roussouly classication describes the spinal shapes of the curvatures by dening the apex and the number of spinal segments within each curvature and the inection point between opposing curvatures. Five different spine types with distinguishable characteristics have been dened, in normative databases [2]. This approach is the rst to classify patients instead of using universally constant targets. It accounts for the distribution of loads and denes compensatory mechanisms and degeneration processes. Disadvantages include difculty of determining the original spine type once degeneration/pathology occurs and difculties experienced in terms of interpretation and explication since this is an analysis method based on visuals.

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50.3.3 GAP Score

The concept of chain of correlations forms the basis of the GAP Score. It implies that the amount of every spinal curvature affects the amount of the next curvature. The pelvis acts as the link between the spine and legs, and it is considered to be the foundation of the spine. Thus, sagittal angular width (PI) and tilt of the pelvis is in close relation with the sagittal spinal curvatures. For example, a patient with a larger horizontal diameter of the pelvis will have a more tilted pelvis while standing; a patient with a more tilted pelvis will have a deeper lumbar lordosis; a patient with a deeper lordosis will have a larger thoracic kyphosis; and a patient with a larger kyphosis will have a deeper cervical lordosis, and vice versa.

The PI, having a wide distribution within the population that does not change during adult life, is considered as a signature of a given individual. Since all other curvature measurements are affected by diseases and degeneration, their absolute values cannot be directly used. In GAP analyses, all sagittal plane parameters are subject to assessment in proportion to PI and calculated as deviations from the “ideal,” in a PI-adjusted manner. This personalized approach is developed from a spinal deformity database, which includes patients treated for spinal disorders, by taking mechanical complications into consideration [3].

Besides the concept of using PI-adjusted relative angular values for the pelvic, lordotic, and global alignment measurements, the GAP score also comprises the mathematical formulation of the distribution of lordosis. Similarly, ideal lordosis distribution has different thresholds depending on the PI.The fth parameter contributing to the GAP score, age factor, is a surrogate for the biology of aging such as osteoporosis, neurodegenerative diseases, and sarcopenia. The numerical value of the GAP score indicates the deviation from ideal and the amount of compensation used and denes the spinopelvic state into proportioned, moderately disproportioned, and severely disproportioned (Fig.50.1).

The main advantage of this approach is that it does not categorize patients but instead calculates their standing posture as a continuum of states. It denotes normal and pathologic in a single score and helps differentiate between deformity and compensation. More importantly, it correlates with the mechanical complications and satisfaction related to the treatment. Disadvantages include controversy in external validation efforts and lack of prospective evaluation.

50.4 Expected Outcomes

Malalignment in the sagittal plane affects the health-related quality of life and presents generally with pain and disability (Chap. 41). It is anticipated that spinal diseases will be of concern to >60% of people who are above 60years of age. When compared to cardiac diseases, diabetes, and chronic obstructive pulmonary disease, it was reported that spinal conditions affect the public health at least as much as

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C. Yilgor et al.

Fig. 50.1 (a) A 56-year-old patient applied to the clinic with complaints of back pain, left leg pain, and claudication. Her neurological examination revealed 3/5 strength in ankle plantar exion and 2/5 strength in extensor hallucis longus. She had a history of numerous conservative treatment sessions over the past couple of years. (b) She was treated with two-staged operation, in which L4–L5 and L5–S1 anterior lumbar interbody fusion and L2–L3 and L3–L4 transforaminal lumbar interbody fusion with T10 to pelvis posterior instrumented fusion was performed. (c) Preoperatively, lumbar vertebrae showed a kyphotic orientation with sagittal malalignment. (d) Segmental and total lordosis correction magnitudes were planned according to GAP score and interbody cage sizes, and wedge angles were decided accordingly

these chronic diseases. Therefore, the preservation of spinal health gains more importance for a person’s quality of life.

Further importance of the sagittal alignment lies in its relation to the occurrence of mechanical complications. Various studies indicated patient-related factors,

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technical factors, and sagittal plane to be the most important factors affecting the development and prevention of mechanical complications. The most common errors in the sagittal plane are being unable to achieve personalized curvatures and, consequently, performing under- or overcorrection (Video 50.3).

Most complications that result in mechanical problems consist of proximal and distal junctional kyphosis and failures, adjacent segment degeneration, implantrelated complications (screw loosening, cage and screw pullouts, etc.), nonunion, and rod fractures. Approximately 50% of patients who experience a mechanical complication require a second intervention.

50.5 What Should Patient andFamily Know?

Sagittal alignment is complex and hard to interpret. It is obvious that every individual has unique anatomy that is regulated mainly by the pelvic shape. Sagittal malalignment and accompanying compensatory mechanisms may be the underlying cause of back pain for many patients with degenerative conditions. Thus, treatment success and avoidance of complications rely on the subject-specic evaluation and adapting a personalized treatment planning.