Flatback syndrome occurs when the lower spine loses its curve and becomes straight. This can cause symptoms, such as persistent back pain and an inability to stand upright.

The human spine has several natural curves that give it its characteristic “S” shape. This includes the natural forward curve (kyphosis) at the chest level and the backward (lordosis) curve just above the buttocks.

The curves help absorb and distribute stresses that occur as the body moves. They also buffer gravity’s effects and ensure an optimal posture.

Loss of any of these natural curvatures results in a front-to-back imbalance, a sagittal imbalance, in the spine.

Sagittal imbalance can occur from any condition that pushes the body’s center of mass forward.

This article explores flatback syndrome, its symptoms, causes, and treatment. It also lists exercises and postural techniques to help people with flatback syndrome.

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Medical Illustration by Bailey Mariner

Flatback syndrome (FBS) is a sagittal imbalance where the lower spine, the lumbar region, loses its natural curvature and becomes flat over time.

This decreased curvature (lordosis) causes an imbalance in the spine, causing the person to lean forward and have difficulty standing upright and walking efficiently.

Learn more about the anatomy of the back here.

The rest of the spine compensates for the imbalance to maintain a more neutral spine. This includes assuming a forward head posture, tilting their pelvis, or flexing their hips and knees.

However, this is physically taxing and will cause muscle fatigue and pain over time.

Learn more about spinal problems here.

A person with flatback syndrome may experience a significant loss of function and be unable to perform their daily activities.

They may also show the following characteristics:

  • an inability to stand up straight
  • their posture is bent forward, head and shoulders slouched forward
  • bent hips and knees to maintain an upright posture
  • fatigue, due to strain on the lower back and leg muscles
  • a reduced natural spinal curvature
  • back pain

A common association is between flatback syndrome and the Harrington rod procedure, a spinal fusion treatment for scoliosis.

People who undergo this procedure compensate with the unnatural straightening of their spine. After decades, the disks under the fusion eventually degenerate, preventing the person from standing upright. This leads to significant disability and chronic back pain.

Other potential causes and risk factors for flatback syndrome include:

It can also be present at birth (congenital), such as when a baby is born with an underdeveloped vertebra.

A doctor will make a diagnosis based on a person’s medical history, including prior spinal surgeries and conditions and a series of exams, including a:

  • spinal exam
  • gait exam
  • neurologic exam
  • musculoskeletal exam

They may also order a 36-inch standing X-ray to evaluate the alignment, symmetry, and compensations in the spine. This X-ray can help determine the severity of a person’s flatback syndrome.

Advanced imaging procedures, such as CT scans and MRIs can help evaluate the person’s condition and identify other issues affecting their spinal alignment.

There are nonsurgical and surgical treatment options available for people with flatback syndrome that depend upon the cause of the condition.

Nonsurgical treatments

Nonsurgical treatments include:

A 2018 study reports improvements in two patients’ sagittal lumbar lordosis and pain after using lumbar extension traction for 16.5 to 20 weeks. Lumbar extension traction is spinal manipulative therapy that involves applying a stretching force to the lumbar vertebrate through weights or pulleys.

Surgical treatments

Healthcare professionals may recommend surgical treatment if these nonoperative measures do not improve the person’s symptoms or if the malalignment or structural problems are severe.

The goals of surgery are to:

  • restore the spine’s curvature and alignment
  • provide pain relief
  • prevent a worsening of the misalignment

The surgical procedure will depend on the person’s spinal needs. A surgeon may do one of the following procedures:

  • posterior osteotomy
  • pedicle subtraction osteotomy
  • vertebral column resection
  • anterior-posterior osteotomy

Exercise and postural techniques can help alleviate the symptoms of flatback syndrome.

A 2021 study found that corrective exercises, which focus on the correction of the thoracolumbar spine, and resistive exercises, which focus on whole-body strengthening, were effective in treating flatback syndrome.

Learn more about exercises to improve posture.

Exercises may focus on correcting the muscle imbalance that keeps the lower back flat. This involves exercises and postural techniques that improve spinal stabilization, range of motion, and core strength.

Examples include:

  • side-lying leg raises
  • chin-ups and pullups
  • planks
  • hamstring stretches
  • chest and abdominal stretches
  • back extensions

Read about more exercises to strengthen the lower back.

Nonoperative management for sagittal imbalances is frequently unsuccessful.

Meanwhile, the overall outlook of surgical procedures varies from poor to good. The most common postoperative complications are pain and reoccurrence.

Despite this, surgical treatment can improve a person’s quality of life despite significant complication rates.

Besides surgery, corrective posture exercises can also improve symptoms in people with flatback syndrome.

Here are some answers to frequently asked questions about flatback syndrome.

How do I know if I have ankylosing spondylitis?

Diagnosing ankylosing spondylitis can be difficult since symptoms may be similar to more common back problems in the initial stages.

However, some of the most common symptoms include lower back and hip pain and stiffness. This pain worsens with rest or inactivity and improves with movement or exercise. Pain can occur in the middle of the night or after prolonged sitting.

How do you sleep with flatback syndrome?

A person can sleep on their back (supine) with minimal to no pillows under their head to prevent neck and back strain. Side sleeping is also a good position. It is important to place a pillow between the knees to keep the spine in a neutral position.

Is flatback syndrome a disability?

Flatback syndrome can cause a significant disability. A person with flatback syndrome may have persistent, severe pain with stance, balance, and gait problems, which can hinder their ability to function in their day-to-day lives.

Flatback syndrome is a condition that causes an unnatural flattening of the lower spine. It typically occurs after corrective spinal surgery or due to degenerative spine conditions, such as ankylosing spondylitis.

It may cause significant pain, impaired posture, and gait impairments. Doctors recommend nonoperative treatments, such as bracing and exercises, to improve a person’s symptoms.

Surgery may be necessary if the condition is severe or does not improve with other treatments.