An Overview of Flat Back Syndrome

In This Article
Table of Contents

Flat back syndrome (a.k.a. fixed sagittal imbalance) is a reduction or elimination of the normal curve in your lumbar spine. If you have this issues, you may find that standing for long periods of time is difficult. Flat back syndrome can be congenital, due to degenerative processes or trauma, or the result of spinal surgery. Treatment often involves physical therapy, bracing, or surgery.


The spine normally has two curves, which are necessary for balance and to maintain one's center of gravity, allowing for the best biomechanics in movement.

The lumbar spine curves inward where it meets the pelvis, as does the cervical spine in the neck, which is called lordosis. The thoracic spine, called kyphosis, curves outward. The normal lordotic curve is part of the natural spinal alignment; it helps you balance your body as you meet the physical demands of your daily activities.

When these curves are lost, you can have difficulty standing up straight and may stoop forward, especially by the end of the day. You may also find that you have to flex your hips and knees, as well as change the tilt of your pelvis in order to try to stand straight.

With flat back syndrome, you may have the sensation of falling forward. When you look at the body from the side, the sagittal axis (front to back) should align no more than 5 millimeters (mm) from vertical. In flat back syndrome, the center of mass is pushed forward and the axis more than 5 mm from vertical.

Being off-centered, you can have difficulty walking and performing other daily activities, and you may feel fatigued from the strain of trying to maintain balance.

The body compensates for flat back syndrome by carrying the head and neck forward, which can cause strain in those areas, as well as in the upper back and shoulders. It can create chronic back pain.


Flat back syndrome can be the result a variety of processes. It can be congenital (present at birth).

Historically, Harrington-rod spinal instrumentation (used to correct some forms of scoliosis) flattened the lumbar spine and resulted in flat back syndrome, especially with age. While modern surgical techniques have reduced this incidence for scoliosis correction, flat back syndrome can occur after laminectomy done to decompress spinal nerves.

Other causes include:


Diagnosis of flat back syndrome begins with a description of symptoms and medical history (especially of previous spinal deformity or spine surgery).

Your healthcare provider then performs a physical examination, including a musculoskeletal exam and a neurologic exam with you in supine and standing positions. A gait exam can also look for changes you have made to compensate for the loss of spinal curvature.

X-ray imaging of the spine can assess sagittal alignment. Your provider will consider other possible sources of the symptoms before confirming the diagnosis.


Conservative treatment for flat back syndrome includes exercises and physical therapy. To address flat low back posture, stretching and strengthening exercises are used. Perhaps the best strategy is to use exercise to reverse the pattern of muscle imbalance that keeps the flat low back in place. Hamstring and ab stretches are key in this process.

The National Health Service in the United Kingdom recommends the following exercises to strengthen core, buttocks, back, neck, and rear shoulder muscles.

Using a gentle, sustained hamstring stretch held for about 30 seconds at a time (performed once or twice daily) will be the best way to restore proper alignment to your lumbar spine in the case of flat low back posture.

A physical therapist can assess the individual and recommend exercises and other forms of treatment. This can include bracing to provide better support.

Surgical correction may be necessary in some cases to restore alignment. Various kinds of osteotomy, including polysegmental wedge osteotomy, pedical subtraction osteotomy), or posterior vertebral column resection, may be considered.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kim D, Menger RP. Spine sagittal balance. StatPearls. Updated January 9, 2019.

  2. National Health Service. Common posture mistakes and fixes. Updated January, 2016.

  3. Roussouly P, Nnadi C. Sagittal plane deformity: an overview of interpretation and management. Eur Spine J. 2010;19(11):1824–1836. doi:10.1007/s00586-010-1476-9