Scheuermann's Kyphosis (Scheuermann's Disease): Abnormal Curvature of the Spine
A normal, healthy spine should have curves in it. When you look at it from the side, you should see these curves. However, too much curvature in the thoracic spine (mid-back) can be problematic. That’s a condition called kyphosis.
One particular type of kyphosis is Scheuermann’s kyphosis, also known as Scheuermann’s disease. A Danish radiologist first discovered Scheuermann’s in the early 1920s, and the condition is named after him. Scheuermann’s kyphosis is characterized by wedge-shaped vertebrae that cause the thoracic spine to curve forward too much.
Scheuermann's kyphosis develops over time during periods of bone growth (such as puberty). It occurs when the front of the spine doesn't grow as fast as the back of the spine and causes healthy, rectangular-shaped vertebrae to become triangular-shaped and wedged together. This causes the thoracic spine to curve more than normal. Patients become stooped forward with a bent-over posture.
The Normal Spine
In order to better understand this condition, it helps to start with a basic anatomy lesson.
The spinal column (also called the vertebral column) starts at the skull and extends into the pelvis. The column contains 33 vertebrae with cartilaginous discs in between each vertebra that help absorb and distribute shock and keep the vertebrae from grinding together during movement. Healthy vertebrae are rectangular-shaped and stacked one on top of another.
It is normal for the spine to curve from front to back. For some people, however, the thoracic spine (located in the chest area) curves too much (more than 40-45 degrees), giving them the appearance of having a hump on their backs. Sometimes their heads look like they are pitched forward as though resting on their chests. This is called kyphosis.
Causes of Scheuermann's Kyphosis
The exact causes of Scheuermann's kyphosis are still unknown; however, researchers believe it has something to do with interrupted bone growth or an abnormality in how vertebrae develop and grow. This condition seems to run in families. Height and weight may also be contributing factors.
Since Scheuermann's disease occurs during periods of bone growth, it often first appears in adolescence at the time of puberty. Parents typically bring their child in to see the doctor with a complaint of poor posture or slouching, sometimes with sporadic occurrences of fatigue and mild pain in the thoracic area of the spine. In severe cases, patients may have other symptoms including:
- A rigid curve of the spine that gets worse when bending forward and only partially corrects itself when standing
- Co-existent scoliosis
- Chest pain or difficulty breathing caused by decreased lung capacity; only in rare circumstances
Diagnosis: Physical Examination
Before a definite diagnosis can be made, the physician will take a medical history to help rule out other conditions that may have similar symptoms. A physical examination will also be done, which may include the following:
- Adam's Forward Bending Test: the patient is asked to bend forward at the waist. This may reveal a thoracolumbar kyphosis.
- Palpation:Also called a hands-on examination, this helps determine spinal abnormalities by feel. When Scheuermann's disease is present, the thoracic area of the spine is overly curved from the side.
- Range of Motion:The physician assesses the degree to which the patient can bend forward, back, and side to side.
In order to get a definitive diagnosis, x-rays of the spine will be needed. Full-length AP (anterior/posterior) x-rays are taken of the spinal column. The patient stands with arms extended forward while keeping the head erect. X-rays may also be taken while the patient is lying down, to determine curve flexibility and vertebral wedging.
The curvature of the kyphosis is measured in degrees. A curvature with no abnormalities of the vertebrae (and one that easily goes away when the patient lies down) is usually considered postural. However, Scheuermann's disease is diagnosed if a patient has:
- A kyphotic curve of 50 degrees or more
- Three or more adjacent vertebrae that are wedged together by at least 5 degrees per segment (15 degrees total across three segments) (Figure 1)
- Small disc herniations through the endplates of the vertebrae (called Schmorl's nodes)
Figure 1: Zoomed in radiograph showing three or more adjacent vertebrae that are wedged together by at least 5 degrees per segment (Left).
Zoomed in radiograph of normal patient (Right).