Scoliosis: A Three-Dimensional Spinal Deformity

Scoliosis: A Three-Dimensional Spinal Deformity

Scoliosis refers to an atypical sideways curvature of the spine, most commonly identified during childhood or early adolescence.

Typically, the spine exhibits natural curves in the cervical, thoracic, and lumbar regions along the sagittal plane, helping maintain proper head-pelvis alignment and absorbing mechanical forces during motion. However, scoliosis is primarily characterized by an abnormal curvature in the coronal (frontal) plane. While curvature severity is assessed in this plane, the condition is inherently three-dimensional, affecting multiple anatomical planes:

• Coronal Plane – A vertical division separating the body into front (anterior) and back (posterior) sections.
• Sagittal Plane – Divides the body into left and right portions.
• Axial (Transverse) Plane – Runs horizontally, perpendicular to the coronal and sagittal planes.

Diagnostically, scoliosis is quantified using Cobb’s angle, measured in the coronal plane. However, the deformity also involves vertebral rotation in the transverse plane and altered sagittal alignment (e.g., reduced kyphosis). As the curvature progresses, vertebral rotation intensifies, leading to torsional scoliosis, which can cause rib cage asymmetry—forming a convex (protruding) and concave (indented) hemithorax. In severe cases, this rotation results in a visible gibbus deformity, particularly when bending forward.

This structural complexity distinguishes scoliosis from simple lateral bending, as it disrupts spinal biomechanics across all three planes, potentially impacting respiratory and neurological function in advanced stages.

scoliosis clinical presentation

Understanding Spinal Anatomy: Structure and Curvatures

The human spine is a remarkable structure composed of 33 vertebrae, which include:

·24 individual vertebrae (flexibly articulated)

·5 fused vertebrae forming the sacrum

·4 fused vertebrae making up the coccyx (tailbone)

Regions of the Spine

The spine is divided into four key sections, each with distinct characteristics:

1. Cervical Spine (7 vertebrae) – Supports the head and allows neck movement.

2. Thoracic Spine (12 vertebrae) – Connects to the ribs, providing structural stability.

3. Lumbar Spine (5 vertebrae) – Bears most of the body’s weight and enables bending/twisting.

4. Sacral & Coccygeal Spine (fused) – Forms the pelvic foundation.

Variations: Some individuals may have congenital differences, such as hemivertebrae (incomplete vertebrae) or fused segments, which can influence spinal alignment.

Natural Spinal Curves: Essential for Posture and Movement

When viewed from the side, a healthy spine exhibits five natural curves, crucial for balance and shock absorption:

·Cervical Curves

Upper Cervical Curve (Occiput to Axis/C2) – Slightly convex forward.

Lower Cervical Curve (C2 to T2) – A lordotic (inward) curve, helping with neck flexibility.

·Thoracic Curve (T2 to T12)

Concave forward, shaped by deeper posterior vertebral bodies.

Some individuals may have a mild lateral curve (left or right convexity) in the upper thoracic region.

·Lumbar Curve (L1 to Lumbosacral Junction)

Convex forward, supporting upright posture and weight distribution.

·Sacral Curve (Lumbosacral Junction to Coccyx)

Downward and forward concavity, anchoring the spine to the pelvis.

These curves work harmoniously to maintain upright posture, absorb impact, and facilitate movement. Disruptions in these curves—such as excessive kyphosis (hunchback) or lordosis (swayback)—can lead to pain and mobility issues.

Regions of the spine

Why This Matters

Understanding spinal anatomy is crucial for diagnosing conditions like scoliosis, herniated discs, and degenerative disorders. Proper spinal alignment ensures optimal nerve function, flexibility, and overall musculoskeletal health.