Scoliosis is a three-dimensional spinal condition involving a sideways curvature and rotation of the vertebrae. While scoliosis can occur anywhere along the vertebral column, its classification is based on the location of the curve’s center. Thoracolumbar scoliosis is a specific diagnosis for a curve that spans the transitional region between the middle and lower back. This location means the curve affects the mechanics of both the rib cage and the highly mobile lower spine.
Defining Thoracolumbar Scoliosis
Thoracolumbar scoliosis is defined by a spinal curve that includes both the lower part of the thoracic spine and the upper part of the lumbar spine. The thoracic spine is the upper and middle back, characterized by its attachment to the rib cage. The lumbar spine is the lower back that provides flexibility and bears most of the body’s weight. This area, typically spanning vertebrae T11 through L2, is a natural transition zone where the spine moves from a more rigid structure to a highly flexible one.
The curve in this region often appears as a single, long “C” shape, unlike the “S” shape seen in patterns involving two separate curves. Because it affects both the rib-supported thoracic area and the rib-free lumbar area, a thoracolumbar curve introduces unique biomechanical challenges. This curve can significantly impact the distribution of weight and the body’s overall balance and posture.
Identifying the Underlying Causes
Thoracolumbar scoliosis is categorized based on its underlying origin, although the cause remains unknown in the majority of cases. The most frequent form is Idiopathic Scoliosis, accounting for approximately 80% of all cases. This type has no identifiable root cause, though a genetic component is often suspected, and is most commonly diagnosed during the rapid growth period of adolescence.
Congenital Scoliosis is present at birth due to a malformation of the vertebrae during embryonic development, occurring when spinal bones do not form completely or fail to separate properly. Neuromuscular Scoliosis is a complication of underlying conditions affecting the muscles and nerves, such as cerebral palsy or muscular dystrophy. In these cases, weakness or imbalance in the muscles supporting the spine leads to the development of the curve.
Recognizable Symptoms and Signs
The physical manifestations of thoracolumbar scoliosis are often more noticeable on the torso than curves located higher in the spine. A primary sign is an uneven waistline, where the space between the arm and the torso appears different on one side. This asymmetry often extends to the hips, with one hip appearing higher or more prominent due to the shifting of the underlying pelvis.
The sideways curve and rotational component can also cause a noticeable trunk shift, making the entire upper body appear to lean to one side. When the person bends forward at the waist, a prominent lump or “rib hump” may be visible on one side of the lower back, resulting from the rotation of the vertebrae. While back pain is not always present, the muscular fatigue from fighting an imbalanced posture can lead to a dull ache or discomfort, particularly in adults.
Diagnosis and Management Approaches
Diagnosis begins with a physical examination, including the Adam’s forward bend test, which helps reveal the rotational component of the curve. If a spinal curve is suspected, a standing X-ray of the entire spine is necessary to confirm the diagnosis and quantify the severity. Scoliosis is officially diagnosed when the sideways curve measures at least 10 degrees, a measurement taken using the Cobb angle method.
The Cobb angle is measured by drawing lines from the most-tilted vertebrae at the top and bottom of the curve; the angle between these lines determines the curve’s magnitude. This measurement, along with the patient’s age and remaining skeletal growth, guides the management plan. For mild curves, typically less than 25 degrees, the approach is observation with regular check-ups to monitor for progression.
Bracing is recommended for growing patients with moderate curves, usually between 25 and 40 degrees, to prevent the curve from worsening. A custom-fitted thoracolumbar-sacral orthosis (TLSO) brace is the most common type used to hold the spine in a straighter position during growth. Surgical intervention, which involves spinal fusion to correct the curve, is typically reserved for severe curves measuring 40 to 50 degrees or greater, or for curves that progress despite bracing.