Kyphosis may be caused by poor posture during childhood or be the result of abnormally shaped vertebrae or developmental problems with the spine.

The spine

Your spine extends from your skull to your pelvis. It's made up of 24 individual rectangular-shaped bones called vertebrae, which are stacked on top of one another.

The vertebrae are separated by soft pads, or discs, which act as shock absorbers. The vertebrae are held together by tough bands of tissue called ligaments. Together with the spinal muscles, the ligaments give the back its strength.

In cases of kyphosis, the middle section of vertebrae, known as the thoracic vertebrae, are curved out of position.

Everyone has some amount of curvature in their spine to allow space inside the chest for organs such as the heart and lungs. There is a range of curvature which is considered normal. However, excessive curvature can lead to symptoms.

There are several reasons why the vertebrae can be affected in this way.

Poor posture

Poor posture in childhood, such as slouching, leaning back in chairs and carrying heavy schoolbags, can cause the ligaments and muscles that support the vertebrae to stretch. This can pull the thoracic vertebrae out of their normal position, resulting in kyphosis. 

Kyphosis caused by poor posture is known as postural kyphosis.

Abnormally shaped vertebrae

Kyphosis can also be caused when the vertebrae don't develop correctly. They can take on a wedged, triangular shape, rather than the normal rectangular, box-like shape. This leads to the vertebrae being out of position and is known as Scheuermann's kyphosis.

In people with Scheuermann's kyphosis, the ligaments surrounding the veterbrae can also be thicker than normal, which may contribute further to the condition.

It's not known what disrupts the normal formation of the spine. One idea is that the blood supply to the vertebrae becomes disrupted, affecting the growth of the vertebrae. There also appears to be a genetic link, as the condition occasionally runs in families.

Congenital kyphosis

Congenital kyphosis is caused when something disrupts the normal development of the spine before birth. In many cases, two or more of the vertebrae fuse together.

It's often unclear why certain children are affected in this way. However, some cases of congenital kyphosis run in families, so it seems genetics also play a role in this type of kyphosis.

Conditions that cause kyphosis

Conditions that can cause kyphosis include:

• osteoporosis – where the bones become weak and fragile and more likely to break (fracture)
• spondylosis – a term that describes the general "wear and tear" that occurs in the bones, discs and ligaments of the spine as a person gets older
• spina bifida – a condition where the spine hasn't formed properly
• Paget's disease – a condition in which the development of new bone cells is disrupted, resulting in the bones becoming weak
• neurofibromatosis – a genetic disorder that affects the nervous system
• muscular dystrophy – a genetic condition that causes progressive weakening of the muscles
• tuberculosis – a bacterial infection that mainly affects the lungs
• cancer that develops inside the spine or spreads to the spine from another part of the body

Kyphosis can also sometimes develop as a result of an injury to the spine.

Kyphosis can usually be diagnosed by examining your spine and taking an X-ray.

Examination

During the examination, your GP may ask you to do a number of exercises to assess whether your balance and range of movement are affected.

Your GP may also ask you to lie down so they can see whether the curvature of your spine is caused by bad posture or a structural problem.

Although it's not always the case, if your spine straightens when you lie down, it's likely that your kyphosis is caused by poor posture (postural kyphosis).

However, if your spine stills curves while you're lying down, it's likely that kyphosis is caused by a problem with the structure of your spine, as found in the Scheuermann's or congenital types of kyphosis.

X-ray and scans

An X-ray can usually confirm the diagnosis and determine the cause of the kyphosis.

Further scans are usually only required if complex treatment, such as surgery, is being planned, or if you have additional symptoms that suggest your nervous system has been affected, such as numbness in your arms or legs.

If you need additional scans you'll probably have a:

• computerised tomography (CT) scan – where a series of X-rays are taken to build-up a detailed 3-dimensional image of your spine
• magnetic resonance imaging (MRI) scan – where strong, fluctuating magnetic fields are used to produce a detailed image of the inside of your spine

Adults

If you develop kyphosis in adulthood, you'll usually need some additional tests to determine the underlying cause.

The tests you'll be referred for depend on any additional symptoms you have. They may include:

• blood tests – which can check for infections such as tuberculosis
• a bone density scan – a type of X-ray to assess how strong your bones are; this can be useful for diagnosing conditions that cause weakening of the bones, such as osteoporosis or Paget's disease
• CT and MRI scans

Most cases of kyphosis don't require treatment.

Kyphosis caused by poor posture (postural kyphosis) can usually be corrected by improving your posture.

If a child has kyphosis as a result of abnormally shaped vertebrae (Scheuermann's kyphosis), treatment depends on factors such as:

• the person's age
• their sex
• the severity of the curve
• how flexible the curve is

The condition usually stops progressing once a child is older and has stopped growing.

Surgery is often required for children born with congenital kyphosis.

Mild kyphosis

If you have mild to moderate kyphosis, it may be possible to control your symptoms using painkillers and exercise.

Painkillers and exercise

Over-the-counter painkillers, such as ibuprofen or paracetamol, can help relieve any back pain.

Regular exercise and a course of physiotherapy may be recommended to help strengthen the muscles in your back.

Back pain can also be helped by maintaining a healthy weight and activities which strengthen core muscles. For example, yoga, pilates or some martial arts.

Bracing

Teenagers with mild to moderate kyphosis may need to wear a back brace. The brace is worn while the bones are still growing and prevents the curve getting worse.

Wearing a brace may feel restrictive at first. However, most people get used to them after a while. Modern braces are designed to be convenient, so it should still be possible to take part in a wide range of physical activities.

You'll need to wear the brace until the spine stops growing, which is usually around 14 or 15 years old.

Bracing isn't usually recommended for adults who have stopped growing because it won't correct the position of the spine.

Surgery

Surgery can usually correct the appearance of the back and may help to relieve pain but it carries quite a high risk of complications. 

Surgery is only recommended for more severe cases of kyphosis, where it's felt the potential benefits of surgery outweigh the risks.

Surgery for kyphosis would usually be recommended if:

• the curve of your spine is very pronounced
• the curve is causing persistent pain that can't be controlled with medication
• the curve is disrupting your body's other important functions, such as breathing and the nervous system
• without surgery it's likely that the structure of your spine would deteriorate further 

A technique called spinal fusion is usually used to treat kyphosis. It involves joining together the vertebrae responsible for the curve of the spine.

During the operation, an incision is made in your back. The curve in your spine is straightened using metal rods, screws and hooks, and your spine is fused into place using bone grafts. Bone grafts usually use donated bone but it may taken from another place in your body, such as the pelvis.

The procedure takes 4 to 8 hours and is carried out under general anaesthetic.

You may need to stay in hospital for up to a week after the operation, and you may have to wear a back brace for up to 9 months to support your spine while it heals.

You should be able to return to school, college or work after 4 to 6 weeks, and be able to play sports about a year after surgery.

Complications

Complications of spinal fusion surgery can include:

• infection after the operation
• excessive bleeding at the site of the surgery
• accidental damage to the nerves that run through the spine, which could result in a paralysis with loss of bladder and bowel function

Before deciding whether to have spinal surgery, you should discuss the benefits and risks with the doctor in charge of your care.