Last Updated on December 15, 2023
Scoliosis is defined as a lateral abnormal curvature of the spine. That means there is a curvature of the spine to one side. However, there is more to scoliosis than just the lateral curvature. Its deformity also occurs in the anteroposterior or sagittal plane and axial plane.
Thoracic and lumbar curves are the most common scoliotic curves.
Severe uncorrected scoliosis can lead to chronic pain, respiratory deficiencies, and decreased exercise capacity in addition to the deformity of the spine.
It is most often diagnosed in childhood or early adolescence thought can develop in infancy or early childhood. It occurs equally among both genders though females are 8 times more likely to have a curve that may progress.
Relevant Anatomy
Spine is made by stacking of vertebrae and extends from below the skull to its lower and between the upper gluteal region. There are five regions of the spine – cervical, thoracic, lumbar, sacral, and coccygeal.
There are 7 cervical vertebrae, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal.
The main function of the vertebral column is to support the skull and torso, provide a secure enclosure for the spinal cord, and transmit the upper body weight to the lower limbs via the pelvis.
Spine has no lateral curve normally but has curves in the anteroposterior or sagittal plane. These curves enhance the function and biomechanics of the spine.
The spine curves in the cervical and lumbar have convexity anteriorly. These are called lordotic curves. Therefore cervical spine and lumbar spine have natural lordosis. The thoracic spine is concave anteriorly and has natural kyphosis.
These natural curves position the spine centered over the pelvis and absorb mechanical stress better.
Apparently, scoliosis appears as the lateral curve (coronal plane) but scoliosis is more than that and it involves other planes too.
While the degree of curvature is measured on the coronal plane, scoliosis involves the following planes:
- Coronal plane: a vertical plane from head to foot and parallel to the shoulders
- Sagittal plane: divides the body into left and right halves
- Axial plane: parallel to the plane of the ground and at right angles to the coronal and sagittal planes.
For scoliosis to be considered, there should be at least 10° of spinal angulation on the anteroposterior x-ray and there should be associated cerebral rotation.
Types of Scoliosis
It could be classified by many parameters but broadly speaking, there are two types – nonstructural and structural
Nonstructural
In nonstructural scoliosis, the spine has a lateral curvature but there is no structural abnormality in the spine. The curvature is in response to habit or a disease process.
The spine is structurally normal with a lateral curvature, no spinal rotation, and no truncal asymmetry.
Following are examples of nonstructural scoliosis
- Postural: Prolonged use of a wrong posture. Resolves on lying down.
- Compensatory: In leg-length discrepancy. Usually goes off on sitting.
- Sciatic: This curve results from trying to avoid pain from an irritated sciatic nerve
- Inflammatory: Caused by an infective process such as appendicitis. The body curves in response to the disease or abdominal muscle spasm.
- Hysterical or Psychosomatic: Underlying psychological component
Nonstructural scoliosis is not true scoliosis though, just a lateral curve of the spine.
Structural
Structural scoliosis, on the other hand, is the one that involves both lateral curvature and rotation of the vertebrae. Most common type is idiopathic.
Following are the types of structural scoliosis
- Idiopathic
- Neuromuscular
- Congenital
Idiopathic
It is the most common type of scoliosis encountered. It is classified into infantile, juvenile (or childhood), and adolescent depending on the age of onset. Out of these adolescent type is the most common representing almost 90% of the cases and infantile is the least common accounting for less than 1%. Juvenile type accounts for the rest of the cases (about 10%)
- Infantile
- 0-3 years
- Associated with neural and axial abnormalities
- Most of cases resolve spontaneously
- Juvenile
- 4-10 years of age
- Progressive
- This can lead to severe deformity as the substantial growth potential is left
- Curves>30 degrees are almost always progressive
- Adolescent
- >10 years
- Can progress rapidly as this is a period of rapid growth
Neuromuscular
This is secondary to neurological or muscular diseases. This kind progresses more rapidly than idiopathic scoliosis and often requires surgical treatment. Here is the partial list of causes of neuromuscular scoliosis.
- Cerebral palsy
- Spinocerebellar degeneration
- Friedreich’s ataxia
- Hereditary Motor and Sensory Neuropathies
- Trauma
- Spinal tumor
- Syringomyelia
- Poliomyelitis
- Spinal muscular atrophy I-IV
- Muscular dystrophies
- Duchenne and Becker’s
- Limb-girdle
- Facio-scapulo-humeral
- Myotonia dystrophica
- Achondroplasia and hypochondroplasia
- Spondylolisthesis
- Mesenchymal disorders
- Marfan’s syndrome
- Ehlers-Danlos syndrome
- Spina bifida
- Neurofibromatosis
- Rheumatoid disease
- Tumors
- Osteoid osteoma
- Osteoblastoma
- Eosinophilic granuloma
- Intraspinal tumors like ependymoma, astrocytoma, epidermoid cyst
Congenital
It results from embryological malformation of one or more vertebrae. It may occur at any level. The deformity occurs because one part of the spine lengthens at a slower rate than the rest leading to deviation.
The geometry and location of the abnormality determine the rate of progression of the spine.
Congenital scoliosis is usually detected at a younger age than idiopathic. These patients must be evaluated for heart and kidney abnormalities.
Treatment is based on the age, curve progression, type, and location of abnormality.
Often, surgical treatment is required.
Curve Progression- Natural History & Risk Factors
Untreated, the scoliosis curve may worsen. Curve progression may vary with scoliosis. For example, neuromuscular scoliosis progresses more rapidly. Idiopathic curve progression is associated with growth potential left. So for the same degree of curve, a child of 10 years has a higher chance of progression of the curve than 13 years.
The risk factors for curve progression are
- Age of onset
- Female gender
- Curve> 50 degrees
- Remaining growth
The rate of progression is not constant. during growth spurts, the progression is faster.
Untreated, the progression of the curve may lead to
- Constant back pain
- Breathing difficulties
- Heart and lung failure due to crowding of space
- Susceptibility to chest infections such as pneumonia
- severe disability that affects the quality of life and activities of daily living
- Increased risk of osteoporosis
Estimation of Curve Progression
A rough estimation of the progression of the curve can be done by estimating the remaining growth by
- Height measurements
- Menarche and breast development in females
- X-rays
- Whether triradiate cartilage is open or closed
- Risser sign
Curves of greater than 50 degrees may progress even after skeletal maturity
Clinical Presentation and Diagnosis
General Points
As we noted, scoliosis has many causes and presentation would vary.
The diagnosis starts with the history of the condition. The age of presentation is the rough guide to the possible types of scoliosis being presented.
The patient should be examined to rule out noni-diopathic scoliosis. Although common, idiopathic scoliosis is a diagnosis of exclusion.
Very young children are more likely to have congenital type of scoliotic deformity. However, slightly older children may have an infantile type too. While the first one almost always needs surgery, the latter may be treated conservatively.
A patient with neuromuscular type across any age would have other features of the disease suggesting. For example typical features of Marfan (facies, tall), Ehler Danlos (joint laxity) or cerebral palsy. Accordingly, the cause of scoliotic deformity may be attributed and confirmed.
Age at onset younger than 10 years, rapid curve progression, and neurological manifestations indicate nonidiopathic scoliosis.
Only when all the causes have been excluded, the label idiopathic should be made.
History
The deformity is the main concern of the patients. Sometimes, in cases of mild curves or balanced curves, the patient may not be aware and scoliosis is found on the examination for some other problem.
Following are the usual complaints
- Spine deformity- may appear leaning on one side
- Deformities of the rib cage
- Tilted pelvis [one hip more prominent than the other]
- Shoulders are not at the same level
- Chest prominence (some females may notice breast size difference)
- Rib cages are at different heights
- Waist is uneven
The following things should be enquired about during the history
- Age at onset
- Presence of back pain**
- The presence of neurological symptoms
- Weakness
- sensory deficit – Numbaness etc
- gait abnormalities, weakness or sensory
** Back pain is not unusual though not typical of scoliosis. Back pain may be present, especially in long-standing cases. The presence of back pain is common in the adolescent age group. Severe back pain needs to be investigated as it may be telling the presence of some specific condition. For example, acute back pain with fevers may indicate infection. All scoliosis patients with back pain should be looked for any associated condition so that secondary causes (nonidiopathic cases are not missed).
In infants the presentation is different. The following should raise the concern in mind of the parents
- Chest Bulge on one side
- Baby lies on one side
- Prominently curved torso to one side
In the initial period, there is no back pain but it usually occurs in long-standing cases.
Physical Examination
The physical examination of the patient includes the examination of the spine, pelvis, lower limbs, and shoulders.
The examination begins with the overall appearance of the patient, her gait, shoulder symmetry, and pelvic symmetry in the standing position. Then the physician examines the back starting with skin inspection for any dimples, hairy patches, or decoloration.
The type of curve present is noted and the presence of a secondary curve is noted. A secondary curve is the one that has developed in response to the primary curve, in a direction opposite to the primary curve making the deformity S-shaped.
The level of the tip of the curve is noted.
A detailed neurological examination is carried out.
Lower limbs are examined in detail including noting the equality/inequality of the limbs.
Further in-depth examination and probing may be required in case of the findings that suggest the presence of an associated condition. For example, if there is a skin and joint hyperlaxity, workup for connective tissue conditions such as Ehlers-Danlos syndrome may be undertaken.
Curve can be measured clinically using a scoliometer. For assessing the likely curve progression, a pubertal development assessment should be done.
Adam’s Forward Bending Test
It is a simple screening test for scoliosis.
- Ask the patient to bend forward at the waist with knees straight and palms together
- Note the asymmetry in the contours of the back
- A presence of asymmetry indicates the presence of structural scoliosis.
Imaging/Diagnostic Workup
Though the diagnosis of scoliosis is made clinically, imaging is done to quantify the severity and multiplanar assessment. Also these can be done to rule out or confirm suspectedassociated conditions.
X-rays
Standing weight-bearing full spine images are desirable. Whole spine X-rays and CT scans can help assess the curve, its shape, angle, and direction.
The curve(s) should be identified and marked. The absence of change in interpedicular distance signifies the absence of rotation and is not true scoliosis, just a spinal curve. The severity of the scoliosis can be calculated by measuring the Cobb angle. Greater than 10 degrees is considered scoliosis though significant curve is 25-30 degrees and more. Greater than 50 degrees is considered severe and requires more aggressive treatment.
Rotation of the vertebrae can be gauged by looking at the interpedicular distance.
In addition, look for any back pathology, especially in case of back pain (infection, tumor, spondylolisthesis)
CT/MRI
CT/MRI is not needed for scoliosis evaluation per see unless there is a neurological deficit. However, they may be done to look for associated conditions.
Images are typically repeated periodically to assess the progression of the curve and calculate treatment implications.
Treatment
The treatment of scoliosis is guided by
- Location and severity of the curve
- Age of the child
- Skeletal maturity
- Possibility of progression of the curve
The options for the treatment are
- Observation
- Bracing
- Surgery
Observation
In mild cases (curves<25 degrees), just observation is enough. The child may be kept in follow-up for 4-6 monthly examinations.
In those who have attained maturity, x-rays are recommended once every five years if no worsening is present.
Bracing
These are effective in children only and those with curves between 25 degrees and 40 degrees.
A brace may prevent the curve from progressing but would not correct an existing curve. Several different types of braces (Milwaukee brace, Boston brace, and the Charleston bending brace) may be used. Braces have been reported to successfully stop curve progression in about 80 percent. The brace may need to be worn for up to 22-23 every day until growth stops. ).
Compliance and wearing time play a role in the success of treatment by a brace.
[Read about different types of braces in scoliosis]
Surgery
Surgery aims to improve the existing deformity and spinal alignment (leveled shoulder, leveled hips, and head over sacrum along with sagittal alignment). It also aims to prevent curve progression.
Neuromuscular and congenital scoliosis often require surgical treatment.
In idiopathic scoliosis, curves greater than 45 degrees in immature patients and curves greater than 50 degrees in mature patients are treated surgically.
Following surgeries can be performed as needed
- Posterior instrumentation and fusion using a posterior approach
- Anterior instrumentation and fusion using the anterior approach
- Decompressive laminectomy – When decompression is required
References
- Shakil H, Iqbal ZA, Al-Ghadir AH. Scoliosis: review of types of curves, etiological theories and conservative treatment. J Back Musculoskelet Rehabil. 2014;27(2):111-5. [Link]
- Buell TJ, Lark R, Smith JS, Shaffrey CI. An approach for treatment of complex pediatric spinal deformity. In: Steinmetz MP, Berven SH, Benzel EC, eds. Benzel’s Spine Surgery: Techniques, Complication Avoidance, and Management. 5th ed. Philadelphia, PA: Elsevier; 2022:chap 143.
- Negrini S, Di Felice F, Donzelli S, Zaina F. Scoliosis and kyphosis. In: Frontera WR, Silver JK, Rizzo TD Jr, eds. Essentials of Physical Medicine and Rehabilitation: Musculoskeletal Disorders, Pain, and Rehabilitation. 4th ed. Philadelphia, PA: Elsevier; 2019:chap 153.
- Pehrsson K, Larsson S, Oden A, Nachemson A. Long-term follow-up of patients with untreated scoliosis. A study of mortality, causes of death, and symptoms. Spine. 1992;17:1091–6. [Link]
