The section of spine from below the neck to the bottom of the rib cage is called the thoracic spine. From the side, the thoracic spine appears slightly rounded. Its shape is like the letter "C" with the opening of the “C” facing the front of the body. This normal curve is called a kyphosis. With an excessive kyphosis, the thoracic spine takes on a hunchbacked appearance.
Scheuermann's disease (also called Scheuermann's kyphosis) is a condition that usually starts in childhood. It affects less than one percent of the population and occurs mostly in children between the ages of 10 and 12. It affects both boys and girls with a slightly higher number of boys affected. Those who do not receive treatment for the condition during childhood often experience back pain as an adult from the spinal deformity. In some cases Scheuermann’s disease doesn’t develop until adulthood.
This guide will help you understand:
- how the problem develops
- how health care professionals diagnose the condition
- what treatment options are available
- what ProActive Rehab’s approach to treatment is
What parts of the spine are involved?
A healthy human spine has three gradual curves. From the side, the neck and low back curve gently inward. This is called a lordosis. The thoracic kyphosis (outward curve) gives the mid back its slightly rounded appearance. These normal curves help the spine absorb forces from gravity and daily activities, such as lifting.
The angle of normal kyphosis in the thoracic spine varies. The angle increases slightly throughout life both in women and men. During the growth years of adolescence, a normal curve measures between 25 and 40 degrees. In general, kyphosis tends to be more exaggerated in girls. If the curve angles more than 40 degrees in either boys or girls, doctors consider the kyphosis a deformity. Scheuermann's disease causes the thoracic kyphosis to angle too far (more than 45 degrees).
The 12 thoracic vertebrae are numbered from T1 to T12. The main section of each thoracic vertebra is a round block of bone, called the vertebral body. A ring of bone attaches to the back of the vertebral body. This ring surrounds and protects the spinal cord.
In Scheuermann's disease, the front of the vertebral body becomes wedge-shaped, possibly from abnormal growth. This produces a triangular-shaped vertebral body, with the narrow, wedged part closest to the front of the body. The wedge creates a larger bend in the kyphosis of the thoracic spine.
Each vertebral body is separated by an intervertebral disc, which acts like a cushion between them. There is a vertebral end plate between each disc and vertebral body. Sometimes in patients with Scheuermann's disease the material inside one or more of the discs squeezes through the vertebral end plate (which is often weaker in patients with Scheuermann's disease). This disc material forms pockets of material inside the vertebral body, a condition called Schmorl's nodes.
A long ligament called the anterior longitudinal ligament connects on the front of the vertebral bodies. This ligament typically thickens in patients with Scheuermann's disease and adds to the forward pull on the spine, producing more wedging and kyphosis.
Scheuermann’s disease usually produces kyphosis in the middle section of the thorax (the chest), between the shoulder blades. Sometimes, however, it can cause kyphosis in the lower part of the thoracic spine, near the bottom of the rib cage.
Related Document: ProActive Rehab's Guide to Thoracic Spine Anatomy
Why do I have this problem?
Famed for discovering this disease, Scheuermann himself thought a lack of blood to the cartilage around the vertebral body caused the wedging. Though scientists have since disproved this theory, the root cause of the disease is still not definitively known.
Mounting evidence suggests wedging develops as the vertebral body grows. During normal growth, the cartilage around the vertebral body develops evenly and completely into bone. If the change from cartilage to bone doesn't happen evenly, one side of the vertebral body grows at a faster rate. By the time the entire vertebral body turns to bone, one side is taller than the other. This is the wedge shape that leads to the abnormal kyphosis.
Other theories of how Scheuermann's kyphosis starts include:
- childhood osteoporosis
- mechanical reasons
- other reasons
Researchers have suggested that this disease can be passed down in families. Studies have shown multiple families who have passed the disease through the inheritance of certain types of genes. The genetic link is uncommon and remains under investigation.
One medical study found that some patients with Scheuermann's disease had mild osteoporosis (decreased bone mass) even though they were very young. Other studies did not show evidence of osteoporosis. More research is needed to confirm the role of osteoporosis in Scheuermann's disease.
Related Document: ProActive Rehab's Guide to Osteoporosis
Mechanical reasons include strains from bending, heavy lifting, and maintaining poor posture. This theory seems plausible because the back braces used for treating kyphosis work. If a back brace can straighten a bent spine, then perhaps mechanical forces could be causing the increased kyphosis (back braces are discussed in more detail later). Some experts think that tight hamstring muscles (along the back of the thigh) pull on the pelvis contributing to the spinal deformity.
Scientists are not convinced, however, that mechanical reasons cause the disease; rather, these factors likely aggravate the condition. In some cases, it is difficult to tell which came first: the mechanical changes causing the deformity or the deformity resulting in the anatomical and thus mechanical changes.
Other theories put forth that might help explain the cause(s) of Scheuermann’s disease include biochemical changes in the collagen that make up the end-plates causing altered bone growth, above-average disc height, and increased levels of growth hormone.
What does the condition feel like?
A hunched posture or a round back in children usually alerts parents or teachers of the need for a visit to a health care professional. Children don't typically complain of back pain or other symptoms in the early stages of Scheuermann’s disease.
On the contrary, this is not the case in adolescents who are nearing puberty and have kyphosis in the lowest part of the thorax, near the bottom of the rib cage. In these patients, back pain is the main problem. This occurs most often in young, active males. Doctors suspect this unique form of the disease occurs because the condition is overlooked during childhood, delaying treatment.
Adults who have lived with the hunched posture for many years may note worsening pain as they age; they are disturbed by the physical changes and deformity that develop. The pain and/or the physical changes typically cause them to seek medical assistance at which time Scheuermann’s disease is discovered.
Besides having a forward curved spine, most people affected by Scheuermann's disease report back stiffness, a loss of flexibility, and some back pain. Patients generally report feeling discomfort along the sides of the spine, slightly below the main part of the abnormal curve.
The neck and low back try to compensate for the round hunched back by increasing the natural lordosis (inward curve) of these two areas. This particularly puts extra strain on the tissues of the low back. Over many years, this added wear and tear may produce low back pain, however, this mainly occurs in adults who have extra lumbar lordosis from years of untreated Scheuermann's disease.
Degenerative spondylosis is also reported as part of the natural history in middle-aged adults with Scheuermann's kyphosis. Spondylosis is when degenerative changes in the spine (usually from aging) occur. These changes can cause bone spurs to form around the spinal joints and cause the joint spaces to narrow. This can contribute to pain and stiffness in the spine.
All of these changes in spinal alignment are often accompanied by mechanical changes in other areas such as tight shoulder, hip, and leg muscles.
In rare cases of Scheuermann’s disease, the spinal cord is affected. A severe kyphosis stretches the spinal cord over the top of the curve, which can injure the spinal cord. Also, patients with Scheuermann's disease have a greater chance of having a herniated thoracic disc. With a herniated disc the material from inside the disc begins to squeeze out and press on the spinal cord. Nerve symptoms for both a stretched spinal cord as well as a herniated disc include sensations of pins and needles and numbness. In addition the leg muscles may feel weak. Symptoms from an injured spinal cord can also include changes in bowel and bladder function (particularly incontinence).
In the rare situation when the kyphosis angle exceeds 100 degrees, the sharply bent spine puts pressure on the heart, lungs, and intestines. When this occurs, patients may tire quickly, suffer shortness of breath, feel chest pain, and lose their appetite.
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