Adolescent Idiopathic Scoliosis - Classification, Causes, Diagnosis, and Treatment

Introduction:

The word scoliosis is derived from "skoliosis," which means crooked. Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in adolescents between 10 and 18 years of age. Girls are affected more than boys. It is also known as late-onset idiopathic scoliosis.

What Is Adolescent Idiopathic Scoliosis?

Adolescent idiopathic scoliosis is the "C" or "S" shaped curving of the backbone (spine). The spine is curved at a 10-degree angle sideways (primarily on the right side), and it is also characterized by a flat back (hypokyphosis) or rounded back (hyperkyphosis).

How Is Scoliosis Classified?

1) Based on the age of the child, it is classified as:

• Early-onset scoliosis occurs before the age of 10 years.

• Late-onset that happens in children above ten years till the maturity stage.

2) Scoliosis is also classified as:

• Congenital scoliosis is abnormal spine curving that occurs at birth and is caused by improper backbone development.

• Neuromuscular scoliosis is associated with nerve and muscular disorders (muscular dystrophy, cerebral palsy) that cause muscle weakness involved in backbone support.

• Idiopathic scoliosis: The leading cause of scoliosis is unknown, and it is further classified as follows:

• Infantile idiopathic scoliosis is rare and affects babies until three years of age.

• Juvenile idiopathic scoliosis is found in children of 3 to 10 years.

• Adolescent idiopathic scoliosis occurs in children above ten years of age.

What Causes Adolescent Idiopathic Scoliosis?

The causative factor of idiopathic scoliosis is unknown. However, it may be caused due to,

• Genetic Factors - Many genes are responsible for the defective curving of the spine. Children also have a higher chance of developing scoliosis if their parents or siblings have it.

• Environmental Factors - Factors like hormonal problems, nerve and muscular diseases, and abnormalities in bone growth can predispose to scoliosis.

What Are the Clinical Features of Adolescent Idiopathic Scoliosis?

Most of the symptoms remain unnoticed and are found during screening and physical examination. It includes:

• Children with idiopathic scoliosis usually present with back pain.

• Ribs are found to be more prominent on one side than the other.

• The shoulder looks tilted, with one side higher than the other.

• Uneven hips.

What Is the Inheritance Pattern for Adolescent Idiopathic Scoliosis?

Adolescent idiopathic scoliosis may occur sporadically, affecting individuals without a family history, or it may cluster within families. The inheritance pattern remains unclear due to the involvement of numerous genetic and environmental factors. Having a close relative with adolescent idiopathic scoliosis heightens the risk for a child to develop the condition.

How Is Staging for Adolescent Idiopathic Scoliosis Performed?

Staging for spinal deformity, particularly in cases of adolescent idiopathic scoliosis (AIS), is best done using the Lenke classification scheme. This system aims to standardize the naming and description of curves, thereby facilitating treatment decisions. It considers factors like the coronal curve (1-6), the sagittal deformity (-, N, or +), and the lumbar spine modifier (A, B, C), resulting in descriptors like 3C+ or 1B-. While a comprehensive understanding of the Lenke classification is essential for spinal deformity surgeons, detailed education on it exceeds the scope of this discussion.

How Is Adolescent Idiopathic Scoliosis Diagnosed?

The various diagnostic methods of idiopathic scoliosis are as follows:

• Physical Examination: It involves assessing the patient's age, gender, the status of the menstruation cycle, details on back pain, and complete family and medical history. The details of maturity are collected as they are associated with the progression of the spinal curve.

• Adam's Forward Bend Test: This test is also done during the clinical examination. The adolescent is asked to bend forward with feet together, knees straight, and arms hanging down freely. The doctor checks for the pattern of spinal curve, level of shoulders, hip tilts, and evenness. The classical sign includes the prominence of the rib (rib hump), mainly on the convex side of the curve. The rib hump and rotation of the backbone are measured using a scoliometer. The scoliosis is confirmed if the device shows a 7-degree rotation.

• Sitting Test: The patient sits and bends forward. It is done to detect any discrepancy in the leg length as it may cause abnormal spinal curvature.

• X-Ray: A whole spine X-ray is taken to measure the degree of scoliosis, which is known as the Cobb angle. The X-ray also includes the pelvic region, which is helpful in assessing bone formation (ossification) to estimate the growth and development of bone. It is referred to as Risser's sign. Radiographs from the side (lateral) are also done to view hypo-or hyperkyphosis.

• Cobb Method: It is used to measure the degree of scoliosis. In this method, the small bones of the spine (vertebrae) above and below the curve are selected. Two lines are drawn from the top portion of the vertebrae above and the lower part below. An angle is formed along the intersection of these two lines, which is referred to as the Cobb angle.

How Is Adolescent Idiopathic Scoliosis Treated?

The treatment depends on the child's age, degree, and severity of the spine's curve. It includes:

• Observation of the patient for six to 12 months is done if the curve is less than 25 degrees. The patient is followed up with regular radiographs and clinical examination.

• Braces (orthosis) are made of plastics and designed to fit the body comfortably. It is preferred when the degree of the curve is between 25 and 45. The braces do not correct the curve; instead, they prevent further progression. Presently, there are various braces available, namely the Milwaukee brace, Boston brace, etc. It can be worn overnight or throughout the day and removed during physical activities. It is found effective, but the main drawback is children are affected psychologically.

• Surgery is planned to prevent the curve progression for cosmetic purposes and if the degree of the curve is more than 45. It corrects the structural deformities (rotation, fusion) of the spine. The various approaches involved are:

  • An anterior approach is used to correct rigid curves, but it often leads to complications after surgery.

  • The posterior approach is widely preferred as the complications are less, correcting the curve better than the anterior approach.

  • Spinal fusion is another type of surgery done to realign the bones involved in the spinal curve. The bones are correctly aligned and fused using bone grafts (small transplanted bones), and they grow appropriately over time. Metal rods are attached to the spine using screws or wires that hold the bones during the fusion. Later, the bones heal into a solid segment of the spine.

What Is the Prognosis for Adolescent Idiopathic Scoliosis?

Without treatment, patients with adolescent idiopathic scoliosis may experience a progression rate of approximately 0.5 to 1 degree per year once reaching a 50-degree coronal angle. Additionally, in adulthood, spinal curves often become stiffer and more rigid, necessitating more aggressive surgical approaches.

Long-term studies indicate a higher incidence of arthritis and negative body image perception in scoliosis patients, regardless of treatment. Surgical corrections involving chest wall invasion may also lead to pain and reduced lung function.

What Are the Complications Associated With Adolescent Idiopathic Scoliosis?

• Untreated scoliosis can lead to various complications, including the progression of deformity, resulting in back pain, lumbar radiculopathy, cosmetic issues, nerve damage, and potentially cardiac and pulmonary restrictions.

• Patients with untreated scoliosis, particularly those with a curve exceeding 80 degrees in the coronal plane, may experience increased shortness of breath.

• While surgical complications are generally less frequent than in adult spinal deformity surgery, they still occur.

• According to one national data series, post-surgical neurologic injury was estimated at 0.9 percent, respiratory complications at 2.8 percent, cardiac complications at 0.8 percent, infection at 0.5 percent, and gastrointestinal complications at 2.7 percent.

• Delayed infections in the hardware are common.

Conclusion:

Adolescent idiopathic scoliosis is a joint presentation seen in children. The quality of life is not disturbed in case of mild to moderate spinal curvature. The severe curving of the spine can sometimes progress and cause complications. Therefore early recognition of the deformity along with appropriate management is essential to lead a better life. "Catch young, treat young."